Identification and analysis of a static culture-specific cell wall protein, Tir1p/Srp1p in Saccharomyces cerevisiae

A 100-kDa protein was found to be a major cell wall protein in Saccharomyces cerevisiae cells cultured without shaking, but was not present in cells cultured with shaking. The amino acid sequence of this protein was identical to the sequence of Tir1p/Srp1p. TIR1/SRP1 has previously been identified as a gene induced by glucose, cold shock or anaerobiosis and was believed to be a cell membrane protein but not a cell wall protein. However, we found that beta-1,3-glucanase solubilized Tir1p/Srp1p from the cell wall and the purified Tir1p/Srp1p reacted with antiserum to beta-1,6-glucan and contained glucose. These results suggest that Tir1p/Srp1p is a major structural cell wall protein in the static-cultured yeast cells and is bound to the cell wall through beta-1,6-glucan. TIR1/SRP1 mRNA was transcribed only in the static culture and its transcription was regulated by the ROX1 repressor.