| dc.description.abstract | Abstract
Biotinylation, which is covalent binding of a biotin - an essential vitamin to a specific lysine residue of a protein, is mediated by biotin protein ligase (BPL1) in yeast. Biotinylation is a rare post-translational modification and normally occurs in a specific lysine residue positioned in the consensus sequence (A/V)MKM within carboxylases in widely divergent species. While Arc1p of Saccharomyces cerevisiae lacks the consensus sequence (A/V)MKM, it is biotinylated at its SSKD. More interestingly, even though the histone proteins of Candida albicans (CaH2B) lack both (A/V)MKM and SSKD, they can be biotinylated in vivo while histone proteins of S. cerevisiae (ScH2B) cannot. Judging from Western blot probed with HRP-Streptavidin, our results showed that the biotinylation of CaH2B appears to be temperature-dependent; rising the growth temperature from 20oC to 37oC dramatically increased its biotinylation level. Biotinylation level of histones also increased based on the enhancement of exogenous biotin supplement (~0.2 µg/L to 200 μg/L). Despite ten of BPL1s tested (S. cerevisiae BPL1 INVSc1, C. albicans BPL1 SC 5314, S. pombe BPL1 972, and all wild-type of P. stipitis BPL1, V. polyspora BPL1, K. lactis BPL1, L. elongisporus BPL1, P. guilliermondii BPL1, T. phaffii BPL1, D. hansennii BPL1) can successfully substitute ScBPL1 knockout strain, none of them can biotinylate the native histone protein or CaH2B transformants in S. cerevisiae. However, result from in vitro biotinylation assay showed that both of the CaBPL1 and ScBPL1 could attach biotin into the histone protein H2B directly. These results suggesting that S. cerevisiae might contain their own mechanism to inhibit biotinylation of protein histone by biotin protein ligase in vivo.
Keywords: Histone, H2B, biotin protein ligase, Candida albicans, biotinylation | en_US |