Abstract
Protein methylation is one of the post-translational modifications that may have important function. The basic amino acid residues such as histidine, lysine, and arginine can be methylated in vivo; and the methylation on basic amino acid appears irreversible and coupled to protein synthesis. In this study, I characterized the methylation of the 70-KDa heat shock proteins (Ssa1p and Ssa2p) in Saccharomyces cerevisiae. I showed that Ssa1p and Ssa2p were methylated in cells grown under normal conditions. The Ssa1p and Ssa2p are methylated on lysine as well as arginine residue(s). I also intended to identify the Ssa1p and Ssa2p-specific S-adenosylmethionine (AdoMet)-dependent methyl-transferases. On first trial, it appeared that Ynl092wp might be responsible for the methylation of Ssa1p or Ssa2p. Then, the double deletion strain was generated for further study. It is clear that Ynl092wp was not a Ssa1p-specific methyltransferase. However, the ssa1Δ ynl092wΔ double mutant was not obtained. Thus, it remains to be determined if Ynl092wp is a methyltransferase responsible for the methylation of Ssa2p. Moreover, biological functions of methylated Ssa1p and Ssa2p need to been determined. It might have important function in cell regulation or substrate interaction.