A Novel Family of Cell Wall-Related Proteins Regulated Differently during the Yeast Life Cycle

Abstract

The Saccharomyces cerevisiae Ygr189c, Yel040w, and Ylr213c gene products show significant homologies among themselves and with various bacterial ␤-glucanases and eukaryotic endotransglycosidases. Deletion of the corresponding genes, either individually or in combination, did not produce a lethal phenotype. However, the removal of YGR189c and YEL040w, but not YLR213c, caused additive sensitivity to compounds that interfere with cell wall construction, such as Congo red and Calcofluor White, and overexpression of YEL040w led to resistance to these compounds. These genes were renamed CRH1 and CRH2, respectively, for Congo red hypersensitive. By site-directed mutagenesis we found that the putative glycosidase domain of CRH1 was critical for its function in complementing hypersensitivity to the inhibitors. The involvement of CRH1 and CRH2 in the development of cell wall architecture was clearly shown, since the alkali-soluble glucan fraction in the crh1⌬ crh2⌬ strain was almost twice the level in the wild-type. Interestingly, the three genes were subject to different patterns of transcriptional regulation. CRH1 and YLR213c (renamed CRR1, for CRH related) were found to be cell cycle regulated and also expressed under sporulation conditions, whereas CRH2 expression did not vary during the mitotic cycle. Crh1 and Crh2 are localized at the cell surface, particularly in chitin-rich areas. Consistent with the observed expression patterns, Crh1-green fluorescent protein was found at the incipient bud site, around the septum area in later stages of budding, and in ascospore envelopes. Crh2 was found to localize mainly at the bud neck throughout the whole budding cycle, in mating projections and zygotes, but not in ascospores. These data suggest that the members of this family of putative glycosidases might exert a common role in cell wall organization at different stages of the yeast life cycle.

Sensing of mammalian IL-17A regulates fungal adaptation and virulence

“…4c). Consistent with the notion that Crh11p, more than Crh12p, is cell cycle regulated and expressed under sporulation conditions 23 , of the two mutant strains, crh11∆ but not crh12∆ failed to respond to IL-17A with adhesion and filamentation ( Supplementary Fig. S4c,d) (Supplementary Methods) as well as with internalization of bound IL-17A (Fig.…”

“…Although it was previously recognized that IFN-γ inhibits yeast-to-hyphal transition in C. albicans 14 , little progress had been made on the mechanistic details of this early observation. Our data show that a conserved family of GPI-anchored crosslinking enzymes, highly conserved in Candida and Aspergillus, and known to be exposed at growing sites-such as bud emergences or hyphal tips 22,23 -and detectable in mice 28,30,31 as well as in humans 32 , mediates IL-17A sensing by fungi. Thus, in addition to their involvement in adhesion and virulence 6,12 , these proteins are immunologically reactive.…”

The GPI‐anchored Gas and Crh families are fungal antigens

“…The plasmid pSK-CRH1 (including the ORF of CRH1 from Saccharomyces cerevisiae) was generated by cloning the SspI fragment of 1.5 kb from pJV89C (Rodriguez-Peña et al, 2000) into the pBluescript SK vector (Stratagene) previously cleaved with SmaI.…”

Uncoupling reproduction from metabolism extends chronological lifespan in yeast

“…A third cluster of down-regulated transcripts (Fig. S6F) included those whose products play essential roles in iron assimilation and metabolism and in cytokinesis (e.g., HOF1, UTR2) (37,38).…”