engleski

The PMTs: an evolutionarily conserved family of protein O-mannosyltransferases

Protein O-mannosylation is an essential protein modification in yeast. Furthermore, it is indispensable for cell morphology and cell wall integrity. Yet, how O-mannosylation affects cell wall architecture is still obscure. In yeasts protein O-mannosylation is initiated at the endoplasmic reticulum by an evolutionarily conserved family of protein O-mannosyltransferases, the PMTs. Phylogenetic analyses revealed that PMTs can be divided into the PMT1, PMT2 and PMT4 subfamily. Here we discuss distinct features of PMT1/PMT2 and PMT4 subfamily members, such as molecular organization and substrate specificities. Further, characterizing pmt mutants we found that their phenotype closely resembles mutants of the cell wal integrity signaling (PKC1-) pathway which monitors cell wal stability. Analysis of the PKC1-pathway revealed that O-mannosylation is essential for induction of the this signal transduction cascade upon external stresses. Biochemical analysis of the highly O-mannosylated upstream receptors of the cell wall integrity pathway showed the abated O-mannosylation affects their maturation, stability and function.

protein glycosylation; O-glycosylation; yeast mannoproteins

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