| 1. |
- Fueller, F., et al.
(författare)
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Endoproteolytic processing of RhoA by Rce1 is required for the cleavage of RhoA by Yersinia enterocolitica outer protein T
- 2006
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Ingår i: Infect Immun. ; 74:3, s. 1712-1717
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Tidskriftsartikel (refereegranskat)abstract
- The bacterial toxin Yersinia outer protein T (YopT) is a cysteine protease that cleaves Rho GTPases immediately upstream of a carboxyl-terminal isoprenylcysteine. By clipping off the lipid anchor, YopT releases Rho GTPases from membranes, resulting in rounding up of mammalian cells in culture. The proteolytic activity of YopT depends on the isoprenylation of the cysteine within the carboxyl-terminal CaaX motif, a reaction carried out by geranylgeranyltransferase type I. The CaaX motif (where "a" indicates aliphatic amino acids) of Rho proteins undergoes two additional processing steps: endoproteolytic removal of the last three amino acids (i.e., -aaX) by Rce1 (Ras-converting enzyme 1) and methylation of the geranylgeranylcysteine by Icmt (isoprenylcysteine carboxyl methyltransferase). In in vitro experiments, RhoA retaining -aaX cannot be cleaved by YopT. Nothing is known, however, about the influence of Rce1-mediated removal of -aaX on the activity of YopT in living cells. We hypothesized that Rce1-deficient mouse fibroblasts, in which the geranylgeranylated Rho proteins are not endoproteolytically processed, would be resistant to YopT. Indeed, this was the case. Microinjection of recombinant YopT into Rce1-deficient fibroblasts had no impact on the subcellular localization of RhoA and no impact on cell morphology. To determine if carboxyl methylation is also required for YopT action, we microinjected YopT into Icmt-deficient fibroblasts. In contrast to the results with Rce1-deficient cells, YopT cleaved RhoA and caused rounding up of the Icmt-deficient cells. Our data demonstrate that Rce1-mediated removal of -aaX from isoprenylated Rho GTPases is required for the proteolytic activity of YopT in living cells, whereas carboxyl methylation by Icmt is not.
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| 2. |
- Lerm, Maria, et al.
(författare)
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Deamidation of Cdc42 and Rac by Escherichia coli cytotoxic necrotizing factor 1 : activation of c-Jun N-terminal kinase in HeLa cells
- 1999
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Ingår i: Infection and Immunity. - : American Society for Microbiology. - 0019-9567 .- 1098-5522. ; 67:2, s. 496-503
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Tidskriftsartikel (refereegranskat)abstract
- Recently, Escherichia coli cytotoxic necrotizing factor 1 (CNF1) was shown to activate the low-molecular-mass GTPase RhoA by deamidation of Gln63, thereby inhibiting intrinsic and GTPase-activating protein (GAP)-stimulated GTPase activities (G. Schmidt, P. Sehr, M. Wilm, J. Selzer, M. Mann, and K. Aktories, Nature 387:725-729, 1997; G. Flatau, E. Lemichez, M. Gauthier, P. Chardin, S. Paris, C. Fiorentini, and P. Boquet, Nature 387:729-733, 1997). Here we report that in addition to RhoA, Cdc42 and Rac also are targets for CNF1 in vitro and in intact cells. Treatment of HeLa cells with CNF1 induced a transient formation of microspikes and formation of membrane ruffles. CNF1 caused a transient 10- to 50-fold increase in the activity of the c-Jun N-terminal kinase. Tryptic peptides of Cdc42 obtained from CNF1-treated cells by immunoprecipitation exhibited an increase in mass of 1 Da compared to control peptides, indicating the deamidation of glutamine 61 by the toxin. The same increase in mass was observed with the respective peptides obtained from CNF1-modified recombinant Cdc42 and Rac1. Modification of recombinant Cdc42 and Rac1 by CNF1 inhibited intrinsic and GAP-stimulated GTPase activities and retarded binding of 2'(3')-O-(N-methylanthraniloyl)GDP. The data suggest that recombinant as well as cellular Cdc42 and Rac are substrates for CNF1.
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| 3. |
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| 5. |
- Sakaba, T, et al.
(författare)
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Fast neurotransmitter release regulated by the endocytic scaffold intersectin
- 2013
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490. ; 110:20, s. 8266-8271
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Tidskriftsartikel (refereegranskat)abstract
- Sustained fast neurotransmission requires the rapid replenishment of release-ready synaptic vesicles (SVs) at presynaptic active zones. Although the machineries for exocytic fusion and for subsequent endocytic membrane retrieval have been well characterized, little is known about the mechanisms underlying the rapid recruitment of SVs to release sites. Here we show that the Down syndrome-associated endocytic scaffold protein intersectin 1 is a crucial factor for the recruitment of release-ready SVs. Genetic deletion of intersectin 1 expression or acute interference with intersectin function inhibited the replenishment of release-ready vesicles, resulting in short-term depression, without significantly affecting the rate of endocytic membrane retrieval. Acute perturbation experiments suggest that intersectin-mediated vesicle replenishment involves the association of intersectin with the fissioning enzyme dynamin and with the actin regulatory GTPase CDC42. Our data indicate a role for the endocytic scaffold intersectin in fast neurotransmitter release, which may be of prime importance for information processing in the brain.
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| 6. |
- Thelestam, M, et al.
(författare)
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Cytolethal distending toxins
- 2005
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Ingår i: Reviews of physiology, biochemistry and pharmacology. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0303-4240. ; 152, s. 111-133
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Tidskriftsartikel (refereegranskat)
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| 7. |
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