| 1. |
- Ciopraga, J, et al.
(författare)
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Isolectins from Solanum tuberosum with different detailed carbohydrate binding specificities: unexpected recognition of lactosylceramide by N-acetyllactosamine-binding lectins.
- 2000
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Ingår i: Journal of biochemistry. - 0021-924X. ; 128:5, s. 855-67
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Tidskriftsartikel (refereegranskat)abstract
- Glycosphingolipid recognition by two isolectins from Solanum tuberosum was compared by the chromatogram binding assay. One lectin (PL-I) was isolated from potato tubers by affinity chromatography, and identified by MALDI-TOF mass spectrometry as a homodimer with a subunit molecular mass of 63,000. The other (PL-II) was a commercial lectin, characterized as two homodimeric isolectins with subunit molecular masses of 52,000 and 55,000, respectively. Both lectins recognized N-acetyllactosamine-containing glycosphingolipids, but the fine details of their carbohydrate binding specificities differed. PL-II preferentially bound to glycosphingolipids with N-acetyllactosamine branches, as Galbeta4GlcNAcbeta6(Galbeta4GlcNAcbeta3)Galbeta4Glcbeta1C er. PL-I also recognized this glycosphingolipid, but bound equally well to the linear glycosphingolipid Galbeta4GlcNAcbeta3Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer. Neolactotetraosylceramide and the B5 pentaglycosylceramide were also bound by PL-I, while other glycosphingolipids with only one N-acetyllactosamine unit were non-binding. Surprisingly, both lectins also bound to lactosylceramide, with an absolute requirement for sphingosine and non-hydroxy fatty acids. The inhibition of binding to both lactosylceramide and N-acetyllactosamine-containing glycosphingolipids by N-acetylchitotetraose suggests that lactosylceramide is also accomodated within the N-acetylchitotetraose/N-acetyllactosamine-binding sites of the lectins. Through docking of glycosphingolipids onto a three-dimensional model of the PL-I hevein binding domain, a Galbeta4GlcNAcbeta3Galbeta4 binding epitope was defined. Furthermore, direct involvement of the ceramide in the binding of lactosylceramide was suggested.
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| 2. |
- Larsson, Thomas, 1947, et al.
(författare)
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Use of an affinity proteomics approach for the identification of low-abundant bacterial adhesins as applied on the Lewis(b)-binding adhesin of Helicobacter pylori.
- 2000
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Ingår i: FEBS letters. - 0014-5793. ; 469:2-3, s. 155-8
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Tidskriftsartikel (refereegranskat)abstract
- Microbial attachment to host cell surfaces is considered to be the first essential step for colonization and infection. In most known cases, attachment is mediated by a specific protein-carbohydrate interaction. We have used a carbohydrate-containing crosslinking probe to select bacterial surface adhesins for trypsin digestion, MALDI-TOF mass spectrometry and identification against genome sequence. The present paper describes this functional proteomics approach for identification of the recently cloned low-abundant Lewis(b)-binding adhesin of Helicobacter pylori. Protein identification was obtained through the enrichment of approximately 300 fmol of adhesin from solubilized cells.
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| 3. |
- Prakobphol, A, et al.
(författare)
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Salivary agglutinin, which binds Streptococcus mutans and Helicobacter pylori, is the lung scavenger receptor cysteine-rich protein gp-340.
- 2000
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Ingår i: The Journal of biological chemistry. - 0021-9258 .- 1083-351X. ; 275:51, s. 39860-6
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Tidskriftsartikel (refereegranskat)abstract
- Salivary agglutinin is a high molecular mass component of human saliva that binds Streptococcus mutans, an oral bacterium implicated in dental caries. To study its protein sequence, we isolated the agglutinin from human parotid saliva. After trypsin digestion, a portion was analyzed by matrix-assisted laser/desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), which gave the molecular mass of 14 unique peptides. The remainder of the digest was subjected to high performance liquid chromatography, and the separated peptides were analyzed by MALDI-TOF/post-source decay; the spectra gave the sequences of five peptides. The molecular mass and peptide sequence information showed that salivary agglutinin peptides were identical to sequences in lung (lavage) gp-340, a member of the scavenger receptor cysteine-rich protein family. Immunoblotting with antibodies that specifically recognized either lung gp-340 or the agglutinin confirmed that the salivary agglutinin was gp-340. Immunoblotting with an antibody specific to the sialyl Le(x) carbohydrate epitope detected expression on the salivary but not the lung glycoprotein, possible evidence of different glycoforms. The salivary agglutinin also interacted with Helicobacter pylori, implicated in gastritis and peptic ulcer disease, Streptococcus agalactiae, implicated in neonatal meningitis, and several oral commensal streptococci. These results identify the salivary agglutinin as gp-340 and suggest it binds bacteria that are important determinants of either the oral ecology or systemic diseases.
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| 4. |
- Spåhr, H, et al.
(författare)
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Purification and characterization of RNA polymerase II holoenzyme from Schizosaccharomyces pombe.
- 2000
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Ingår i: The Journal of biological chemistry. - : Elsevier BV. - 0021-9258. ; 275:2, s. 1351-6
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Tidskriftsartikel (refereegranskat)abstract
- We have purified the RNA polymerase II holoenzyme from Schizosaccharomyces pombe to near homogeneity. The Mediator complex is considerably smaller than its counterpart in Saccharomyces cerevisiae, containing only nine polypeptides larger than 19 kDa. Five of these Mediator subunits have been identified as the S. pombe homologs to Rgr1, Srb4, Med7, and Nut2 found in S. cerevisiae and the gene product of a previously uncharacterized open reading frame, PMC2, with no clear homologies to any described protein. The presence of Mediator in a S. pombe RNA polymerase II holoenzyme stimulated phosphorylation of the C-terminal domain by TFIIH purified from S. pombe. This stimulation was species-specific, because S. pombe Mediator could not stimulate TFIIH purified from S. cerevisiae. We suggest that the overall structure and mechanism of the Mediator is evolutionary conserved. The subunit composition, however, has evolved to respond properly to physiological signals.
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