| 1. |
- Karlsson, Maria, 1985, et al.
(författare)
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Reconstitution of water channel function of an aquaporin overexpressed and purified from Pichia pastoris.
- 2003
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Ingår i: FEBS Letters. - 1873-3468 .- 0014-5793. ; 537:1-3, s. 68-72
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Tidskriftsartikel (refereegranskat)abstract
- The aquaporin PM28A is one of the major integral proteins in spinach leaf plasma membranes. Phosphorylation/dephosphorylation of Ser274 at the C-terminus and of Ser115 in the first cytoplasmic loop has been shown to regulate the water channel activity of PM28A when expressed in Xenopus oocytes. To understand the mechanisms of the phosphorylation-mediated gating of the channel the structure of PM28A is required. In a first step we have used the methylotrophic yeast Pichia pastoris for expression of the pm28a gene. The expressed protein has a molecular mass of 32462 Da as determined by matrix-assisted laser desorption ionization-mass spectrometry, forms tetramers as revealed by electron microscopy and is functionally active when reconstituted in proteoliposomes. PM28A was efficiently solubilized from urea- and alkali-stripped Pichia membranes by octyl-beta-D-thioglucopyranoside resulting in a final yield of 25 mg of purified protein per liter of cell culture.
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| 2. |
- Persson, Daniel, 1972, et al.
(författare)
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Penetratin-induced Aggregation and Subsequent Dissociation of Negatively Charged Phospholipid Vesicles
- 2001
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Ingår i: FEBS Letters. - 1873-3468 .- 0014-5793. ; 505:2, s. 307-312
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Tidskriftsartikel (refereegranskat)abstract
- The interaction of the cellular delivery vector penetratin with a model system consisting of negatively charged phospholipid vesicles has been studied. Above a certain peptide to lipid molar ratio, the cationic oligopeptide induces vesicle aggregation. Interestingly, the aggregation is followed by spontaneous disaggregation, which may be related to membrane translocation of the peptide. Circular dichroism (CD) measurements indicate a conformational transition, from alpha -helix to antiparallel beta -pleated sheet, which is simultaneous with the aggregation process. The potential influence of spectroscopic artifacts on CD data due to the drastically increased turbidity during aggregation is discussed.
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| 3. |
- Struglics, André, et al.
(författare)
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Protein phosphorylation/dephosphorylation in the inner membrane of potato tuber mitochondria
- 2000
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Ingår i: FEBS Letters. - 0014-5793. ; 475:3, s. 213-217
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Tidskriftsartikel (refereegranskat)abstract
- Inside-out inner mitochondrial membranes free of matrix proteins were isolated from purified potato tuber (Solanum tuberosum L.) mitochondria and incubated with [γ-32P]ATP. Proteins were separated by SDS-PAGE and visualized by autoradiography. Phosphorylation of inner membrane proteins, including ATPase subunits, was strongly inhibited by the phosphoprotein phosphatase inhibitor NaF. We propose that an inner membrane phosphoprotein phosphatase is required for activation of the inner membrane protein kinase. When prelabelled inner membranes were incubated in the absence of [γ- 32P]ATP, there was no phosphoprotein dephosphorylation unless a soluble matrix fraction was added. This dephosphorylation was inhibited by NaF, but not by okadaic acid. We conclude that the mitochondrial matrix contains a phosphoprotein phosphatase that is responsible for dephosphorylation of inner membrane phosphoproteins. (C) 2000 Federation of European Biochemical Societies.
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| 4. |
- Thoren, Per, 1972, et al.
(författare)
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The Antennapedia peptide penetratin translocates across lipid bilayers - the first direct observation
- 2000
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Ingår i: FEBS Letters. - 1873-3468 .- 0014-5793. ; 482:3, s. 265-268
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Tidskriftsartikel (refereegranskat)abstract
- The potential use of polypeptides and oligonucleotides for therapeutical purposes has been questioned because of their inherently poor cellular uptake. However, the 16-mer oligopeptide penetratin, derived from the homeodomain of Antennapedia, has been reported to enter cells readily via a non-endocytotic and receptor- and transporter-independent pathway, even when conjugated to large hydrophilic molecules. We here present the first study where penetratin is shown to traverse a pure lipid bilayer. The results support the idea that the uptake mechanism involves only the interaction of the peptide with the membrane lipids. Furthermore, we conclude that the translocation does not involve pore formation.
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| 5. |
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| 6. |
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| 7. |
- Chang, Shu-Nu, 1975-, et al.
(författare)
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An acidic amino acid cluster regulates the nucleolar localization and ribosome assembly of human ribosomal protein L22
- 2000
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Ingår i: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 484:1, s. 22-28
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Tidskriftsartikel (refereegranskat)abstract
- The control of human ribosomal protein L22 (rpL22) to enter into the nucleolus and its ability to be assembled into the ribosome is regulated by its sequence. The nuclear import of rpL22 depends on a classical nuclear localization signal of four lysines at positions 13-16. RpL22 normally enters the nucleolus via a compulsory sequence of KKYLKK (I-domain, positions 88-93). An acidic residue cluster at the C-terminal end (C-domain) plays a nuclear retention role. The retention is concealed by the N-domain (positions 1-9) which weakly interacts with the C-domain as demonstrated in the yeast two-hybrid system. Once it reaches the nucleolus, the question of whether rpL22 is assembled into the ribosome depends upon the presence of the N-domain. This suggests that the N-domain, on dissociation from its interaction with the C-domain, binds to a specific region of the 28S rRNA for ribosome assembly.
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| 8. |
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| 9. |
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| 10. |
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| 11. |
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| 12. |
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| 13. |
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| 14. |
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| 15. |
- Jonsson, AP, et al.
(författare)
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A novel Ser O-glucuronidation in acidic proline-rich proteins identified by tandem mass spectrometry.
- 2000
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Ingår i: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 475:2, s. 131-4
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Tidskriftsartikel (refereegranskat)abstract
- Human acidic proline-rich salivary protein PRP-1 and its C-terminally truncated form PRP-3 were analyzed by electrospray tandem mass spectrometry. Post-translational modifications were detected and characterized. A pyroglutamic acid residue was demonstrated at the N-terminus, Ser-8 and Ser-22 were shown to be phosphorylated and an O-linked glucuronic acid conjugation was identified. The latter modification was located to Ser-17 and found to be present in approximately 40% of the polypeptides.
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| 16. |
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| 17. |
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| 18. |
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| 19. |
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| 20. |
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| 21. |
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| 22. |
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| 23. |
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| 24. |
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| 25. |
- Alam, M.T., et al.
(författare)
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The importance of being knotted : Effects of the C-terminal knot structure on enzymatic and mechanical properties of bovine carbonic anhydrase II1
- 2002
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Ingår i: FEBS Letters. - 0014-5793 .- 1873-3468. ; 519:1-3, s. 35-40
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Tidskriftsartikel (refereegranskat)abstract
- In order to better understand the contribution of the knotted folding pattern to the enzymatic and mechanical properties of carbonic anhydrases, we replaced Gln-253 of bovine carbonic anhydrase II with Cys, which allowed us to measure the mechanical strength of the protein against tensile deformation by avoiding knot tightening. The expressed protein, to our surprise, turned out to contain two conformational isomers, one capable of binding an enzymatic inhibitor and the other not, which led to their separation through affinity chromatography. In near- and far-UV circular dichroism and fluorescence spectra, the separated conformers were very similar to each other and to the wild-type enzyme, indicating that they both had native-like conformations. We describe new evidence which supports the notion that the difference between the two conformers is likely to be related to the completeness of the C-terminal knot formation. © 2002 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.
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| 26. |
- Alleva, R., et al.
(författare)
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Coenzyme Q blocks biochemical but not receptor-mediated apoptosis by increasing mitochondrial antioxidant protection
- 2001
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Ingår i: FEBS Letters. - 0014-5793 .- 1873-3468. ; 503:1, s. 46-50
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Tidskriftsartikel (refereegranskat)abstract
- Generation of free radicals is often associated with the induction and progression of apoptosis. Therefore, antioxidants can prove anti-apoptotic, and can help to elucidate specific apoptotic pathways. Here we studied whether coenzyme Q, present in membranes in reduced (ubiquinol) or oxidised (ubiquinone) forms, can affect apoptosis induced by various stimuli. Exposure of Jurkat cells to a-tocopheryl succinate (a-TOS), hydrogen peroxide, anti-Fas IgM or TRAIL led to induction of apoptosis. Cell death due to the chemical agents was suppressed in cells enriched with the reduced form of coenzyme Q. However, coenzyme Q did not block cell death induced by the immunological agents. Ubiquinol-10 inhibited reactive oxygen species (ROS) generation in cells exposed to a-TOS, and a mitochondrially targeted coenzyme Q analogue also blocked apoptosis triggered by a-TOS or hydrogen peroxide. Therefore, it is plausible that ubiquinol-10 protects cells from chemically-induced apoptosis by acting as an antioxidant in mitochondria. Our results also indicate that generation of free radicals may not be a critical step in induction of apoptosis by immunological agents. © 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.
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| 27. |
- Basu, Samar, et al.
(författare)
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Biomarkers of free radical injury during spinal cord ischemia
- 2001
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Ingår i: FEBS Letters. - 0014-5793 .- 1873-3468. ; 508:1, s. 36-38
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Tidskriftsartikel (refereegranskat)abstract
- Plasma and urinary levels of 8-iso-PGF(2alpha) and 15-keto-dihydro-PGF(2alpha) were analysed at baseline and during the ischemia-reperfusion period in experimental spinal cord ischemia. A significant and immediate increase of 8-iso-PGF(2alpha) in plasma at the start and up to 60 min, and in the urine at 90-150 min following ischemia indicate an association of oxidative injury. The inflammatory response indicator 15-keto-dihydro-PGF(2alpha) in plasma increased significantly at the start and up to 60 min after ischemia. No such increase was seen in animals with no spinal cord ischemia. Thus, free radical mediated and cyclooxygenase catalysed products of arachidonic acid are increased during spinal cord ischemia as a consequence of oxidative injury and inflammation.
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| 28. |
- Basu, Samar, et al.
(författare)
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Development of a novel biomarker of free radical damage in reperfusion injury after cardiac arrest
- 2000
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Ingår i: FEBS Letters. - 0014-5793 .- 1873-3468. ; 470:1, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- In a porcine model of cardiopulmonary resuscitation (CPR), we investigated changes in the plasma levels of 8-iso-PGF(2alpha), a marker for oxidative injury, and 15-keto-dihydro-PGF(2alpha), an inflammatory response indicator during the post-resuscitation period after cardiac arrest. Twelve piglets were subjected to either 2 or 5 min (VF2 and VF5 group) of ventricular fibrillation (VF) followed by 5 min of closed-chest CPR. Six piglets without cardiac arrest were used as controls. In VF5 group, 8-iso-PGF(2alpha) in the jugular bulb plasma (draining the brain) increased four-fold. Jugular bulb 8-iso-PGF(2alpha) in the control group remained unchanged. The 15-keto-dihydro-PGF(2alpha) also increased four-fold in the VF5 group. Thus, 8-iso-PGF(2alpha) and 15-keto-dihydro-PGF(2alpha) measurements in jugular bulb plasma may be used as biomarkers for quantification of free radical catalyzed oxidative brain injury and inflammatory response in reperfusion injury
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| 29. |
- Bu, Shizhong, et al.
(författare)
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Mechanisms for 2-methoxyestradiol-induced apoptosis of prostate cancer cells
- 2002
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Ingår i: FEBS Letters. - 0014-5793 .- 1873-3468. ; 531:2, s. 141-51
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Tidskriftsartikel (refereegranskat)abstract
- Prostate and breast carcinomas are sex hormone-related carcinomas, which are known to be associated with an over-expression of the proto-oncogene Bcl-2. Here, we report that 2-methoxyestradiol (2-ME), an endogenous metabolite of estrogen that does not bind to nuclear estrogen receptors, effectively induces apoptosis in Bcl-2-expressing human prostate and breast carcinoma cells in vitro and in a rat prostate tumor model in vivo. In several cell lines derived from prostate, breast, liver and colorectal carcinomas, 2-ME treatment led to an activation of c-Jun N-terminal kinase (JNK) and phosphorylation of Bcl-2, which preceded the induction of apoptosis. In summary, our data suggest that 2-ME induces apoptosis in epithelial carcinomas by causing phosphorylation of JNK, which appears to be correlated with phosphorylation of Bcl-2.
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| 30. |
- Chang, Shu-Nu, 1975-, et al.
(författare)
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An acidic amino acid cluster regulates the nucleolar localization and ribosome assembly of human ribosomal protein L22
- 2000
-
Ingår i: FEBS Letters. - 0014-5793 .- 1873-3468. ; 484:1, s. 22-28
-
Tidskriftsartikel (refereegranskat)abstract
- The control of human ribosomal protein L22 (rpL22) to enter into the nucleolus and its ability to be assembled into the ribosome is regulated by its sequence. The nuclear import of rpL22 depends on a classical nuclear localization signal of four lysines at positions 13-16. RpL22 normally enters the nucleolus via a compulsory sequence of KKYLKK (I-domain, positions 88-93). An acidic residue cluster at the C-terminal end (C-domain) plays a nuclear retention role. The retention is concealed by the N-domain (positions 1-9) which weakly interacts with the C-domain as demonstrated in the yeast two-hybrid system. Once it reaches the nucleolus, the question of whether rpL22 is assembled into the ribosome depends upon the presence of the N-domain. This suggests that the N-domain, on dissociation from its interaction with the C-domain, binds to a specific region of the 28S rRNA for ribosome assembly.
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| 31. |
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| 32. |
- Chumnarnsilpa, Sakesit, 1967-, et al.
(författare)
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Activation in isolation : exposure of the actin-binding site in the C-terminal half of gelsolin does not require actin
- 2003
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Ingår i: FEBS Letters. - Netherlands : Elsevier Science B.V.. - 0014-5793 .- 1873-3468. ; 552:2-3, s. 82-85
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Tidskriftsartikel (refereegranskat)abstract
- Gelsolin requires activation to carry out its severing and capping activities on F-actin. Here, we present the structure of the isolated C-terminal half of gelsolin (G4-G6) at 2.0 A resolution in the presence of Ca(2+) ions. This structure completes a triptych of the states of activation of G4-G6 that illuminates its role in the function of gelsolin. Activated G4-G6 displays an open conformation, with the actin-binding site on G4 fully exposed and all three type-2 Ca(2+) sites occupied. Neither actin nor the type-l Ca(2+), which normally is sandwiched between actin and G4, is required to achieve this conformation.
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| 33. |
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| 34. |
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| 35. |
- Edvardsson, Anna, et al.
(författare)
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The major peptidyl-prolyl isomerase activity in thylakoid lumen of plant chloroplasts belongs to a novel cyclophilin TLP20
- 2003
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Ingår i: FEBS Letters. - 0014-5793. ; 542:1-3, s. 137-141
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Tidskriftsartikel (refereegranskat)abstract
- Fractionation of proteins from the thylakoid lumen of spinach chloroplasts combined with peptidyl-prolyl cis/trans isomerase (PPIase) measurements revealed a major isomerase activity that was ascribed to a novel enzyme TLP20 ( hylakoid umen PIase of kDa). TLP20 was inhibited by cyclosporin A and mass spectrometric sequencing of tryptic peptides confirmed its classification as a cyclophilin. Genes encoding similar putative thylakoid cyclophilins with a unique insert of three amino acids NPV in their N-termini were found in chromosome 5 of both Arabidopsis and rice. TLP20 is suggested to be the major PPIase and protein folding catalyst in the thylakoid lumen of plant chloroplasts.
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| 36. |
- Flach, Carl-Fredrik, 1977, et al.
(författare)
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Cholera toxin induces expression of ion channels and carriers in rat small intestinal mucosa.
- 2004
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Ingår i: FEBS letters. - 0014-5793. ; 561:1-3, s. 122-6
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Tidskriftsartikel (refereegranskat)abstract
- Cholera toxin causes cyclic adenosine monophosphate (cAMP)-induced electrolyte and water secretion in the small intestine. The toxin-induced change in gene expression in rat small intestine was evaluated with microarray technique and the results were confirmed by semiquantitative polymerase chain reaction (PCR). The transporter CNT2 for nucleosides was upregulated between 6 and 18 h after challenge, whereas the level of GLUT1 transporter for glucose became elevated at 6 h. Both changes probably facilitate uptake of these nutrients in the gut. At 18 h, the major chloride channel in the villus, ClC2, was upregulated. Aquaporin 8 was downregulated at 6 h and two mucin-producing genes were upregulated 18 h after toxin challenge. The expression was back to normal after 72 h, which is the turnover time for intestinal epithelial cells.
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| 37. |
- Fredriksson, Robert, et al.
(författare)
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Novel human G protein-coupled receptors with long N-terminals containing GPS domains and Ser/Thr-rich regions
- 2002
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Ingår i: FEBS Letters. - 0014-5793 .- 1873-3468. ; 531:3, s. 407-414
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Tidskriftsartikel (refereegranskat)abstract
- We report eight novel members of the superfamily of human G protein-coupled receptors (GPCRs) found by searches in the human genome databases, termed GPR97, GPR110, GPR111, GPR112, GPR113, GPR114, GPR115 and GPR116. Phylogenetic analysis shows that these are additional members of a family of GPCRs with long N-termini, previously termed EGF-7TM, LNB-7TM, B2 or LN-7TM. Five of the receptors form their own phylogenetic cluster, while three others form a cluster with the previously reported HE6 and GPR56 (TM7XN1). All the receptors have a GPS domain in their N-terminus and long Ser/Thr-rich regions forming mucin-like stalks. GPR113 has a hormone binding domain and one EGF domain. GPR112 has over 20 Ser/Thr repeats and a pentraxin domain. GPR116 has two immunoglobulin-like repeats and a SEA box. We found several human EST sequences for most of the receptors showing differential expression patterns, which may indicate that some of these receptors participate in reproductive functions while others are more likely to have a role in the immune system.
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| 38. |
- Funk, Christiane, et al.
(författare)
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D1' centers are less efficient than normal photosystem II centers
- 2001
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Ingår i: FEBS Letters. - 0014-5793 .- 1873-3468. ; 505:1, s. 113-117
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Tidskriftsartikel (refereegranskat)abstract
- One prominent difference between the photosystem II (PSII) reaction center protein D1 ' in Synechocystis 6803 and normal D1 is the replacement of Phe-186 in D1 with leucine in D1 '. Mutants of Synechocystis 6803 producing only D1 ', or containing engineered D1 proteins with Phe-186 substitutions, were analyzed by 77 K fluorescence emission spectra, chlorophyll a fluorescence induction yield and decay kinetics, and flash-induced oxygen evolution. Compared to D1-containing PSII centers, D1 ' centers exhibited a 50% reduction in variable chlorophyll a fluorescence yield, while the flash-induced O-2 evolution pattern was unaffected. In the F186 mutants, both the P680(+)/Q(A)(-) recombination and O-2 oscillation pattern were noticeably perturbed.
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| 39. |
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| 40. |
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| 41. |
- Grimm, T, et al.
(författare)
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Genomic organization and embryonic expression of Suppressor of Fused, a candidate gene for the split-hand/split-foot malformation type 3
- 2001
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Ingår i: FEBS Letters. - 0014-5793 .- 1873-3468. ; 505:1, s. 13-17
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Tidskriftsartikel (refereegranskat)abstract
- The genes for human and mouse Suppressor of Fused (SU(FU)/Su(Fu)) in the Hedgehog signaling pathway were characterized and found to contain 12 exons. Human SU(FU) localized on chromosome 10q24-25 between the markers D10S192 and AFM183XB12. We detected three additional SU(FU) isoforms, two of which have lost their ability to interact with the transcription factor GLI1. Expression analysis using whole mount in situ hybridization revealed strong expression of Su(Fu) in various mouse embryonic tissues. SU(FU) was considered a candidate gene for the split-hand/split-foot malformation type 3 (SHFM3). However, no alterations in the SU(FU) gene were found in SHFM3 patients.
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| 42. |
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| 43. |
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| 44. |
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| 45. |
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| 46. |
- Hilden, L., et al.
(författare)
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Do the extracellular enzymes cellobiose dehydrogenase and manganese peroxidase form a pathway in lignin biodegradation?
- 2000
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Ingår i: FEBS Letters. - 0014-5793 .- 1873-3468. ; 477:02-jan, s. 79-83
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Tidskriftsartikel (refereegranskat)abstract
- The extracellular enzyme manganese peroxidase is believed to degrade lignin by a hydrogen peroxide-dependent oxidation of Mn(II) to the reactive species Mn(III) that attacks the lignin, However, Mn(III) is not able to directly oxidise the non-phenolic lignin structures that predominate in native lignin, We show here that pretreatment of a non-phenolic lignin model compound with another extracellular fungal enzyme, cellobiose dehydrogenase, allows the manganese peroxidase system to oxidise this molecule. The mechanism behind this effect is demethoxylation and/or hydroxylation, i.e. conversion of a nonphenolic structure to a phenolic one, mediated by hydroxyl radicals generated by cellobiose dehydrogenase, This suggests that cellobiose dehydrogenase and manganese peroxidase may act in an extracellular pathway in fungal lignin biodegradation, Analytical techniques used in this paper are reverse-phase high-pressure liquid chromatography, gas chromatography connected to mass spectroscopy and UV-visible spectroscopy.
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| 47. |
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| 48. |
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| 49. |
- Jimenez, A, et al.
(författare)
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Human spermatid-specific thioredoxin-1 (Sptrx-1) is a two-domain protein with oxidizing activity
- 2002
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Ingår i: FEBS Letters. - 0014-5793 .- 1873-3468. ; 530:1-3, s. 79-84
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Tidskriftsartikel (refereegranskat)abstract
- Spermatid-specific thioredoxin-1 (Sptrx-1) is the first member of the thioredoxin family of proteins with a tissue-specific expression pattern, found exclusively in the tail of elongating spermatids and spermatozoa. We describe here further biochemical characterization of human Sptrx-1 protein structure and enzymatic activity. In gel filtration chromatography human Sptrx-1 eluates as a 400 kDa protein consistent with either an oligomeric form, not maintained by intermolecular disulfide bonding, and/or a highly asymmetrical structure. Analysis of circular dichroism spectra of fragments 1-360 and 361-469 and comparison to spectra of full-length Sptrx-1 supports a two-domain organization with a largely unstructured N-terminal domain and a folded thioredoxin-like C-terminal domain. Functionally, Sptrx-1 behaves as an oxidant in vitro when using selenite, but not oxidized glutathione, as electron acceptor. This oxidizing enzymatic activity suggests that Sptrx-1 might govern the stabilization (by disulfide cross-linking) of the different structures in the developing tail of spermatids and spermatozoa.
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| 50. |
- Kaarniranta, Kai, et al.
(författare)
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Protein synthesis is required for stabilization of hsp70 mRNA upon exposure to both hydrostatic pressurization and elevated temperature.
- 2000
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Ingår i: FEBS Letters. - : Elsevier. - 0014-5793 .- 1873-3468. ; 475:3, s. 283-286
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Tidskriftsartikel (refereegranskat)abstract
- We have recently described that in chondrocytic cells high hydrostatic pressure (HP) causes a heat shock response via mRNA stabilization without a transcriptional activation of the hsp70 gene. In this study, we investigated whether this exceptional regulatory mechanism occurs more generally in different types of cells. Indeed, hsp70 mRNA and protein accumulated in HeLa, HaCat and MG-63 cells under 30 MPa HP, without DNA-binding of heat shock transcription factor 1 (HSF1) to the heat shock element of the hsp70 gene or formation of nuclear HSF1 granules, revealing a lack of transcriptional activation. Moreover, we observed that protein synthesis is needed for mRNA stabilization. Thus, high HP offers a model to study the mechanisms of hsp70 mRNA stabilization without HSF1-mediated induction of the heat shock gene response.
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