Study of tyrosyl-tRNA synthetases (TyrRS) gene expression during sporulation cycle in Saccharomyces cerevisiae by bioinformatic analysis of microarray data showed high correlation of TyrRS expression to genes that participate in cell wall assembly. Furthermore, the cell wall biogenesis protein KNR4 which physically interacts with TyrRS and cooperates in beta-1,3 glucan biosynthesis falls into a single gene cluster with TyrRS. One third of genes (13 from 42) in TyrRS gene cluster are responsible for the functions directly related to cell wall assembly and maintenance during sporulation. Putative transcription factor binding site on TyrRS upstream sequences was localized with expectation maximization algorithm. The site could be involved in the control of TyrRS expression during sporulation. Absence of correlation in gene expression between KNR4 and TyrRS in S. cerevisiae and their homologues in Schizosaccharomyces pombe--genes SPBC30D10.17 and TYR1 as well as the lack of correlation in the expression level of TyrRS with other sporulation cycle genes indicates that participation of TyrRS in cell wall assembly in S. cerevisiae appeared later in evolution after divergence of S. pombe and S. cerevisiae.