A comprehensive analysis of gene expression profiles in a yeast N-glycosylation mutant

Although protein N-glycosylation is critical to many cell functions, its do wnstream targets remain largely unknown. In all eukaryotes, N-glycosylation utilizes the lipid-linked oligosaccharide (LLO) precursor, whose synthesis is initiated by the ALG7 gene. To elucidate the key signaling and metaboli c events affected by N-glycosylation, we performed genomewide expression pr ofiling of yeast cells carrying a hypomorphic allele of ALG7. DNA microarra ys showed that of more than 97% of known or predicted yeast genes, 29 displ ayed increased expression while 23 were repressed in alg7 mutants. Changes in transcript abundance were observed for a and a mating-type genes, for ge nes functioning in several mitogen-activated protein kinase (MAPK) cascades , as well as in phosphate, amino acid, carbohydrate, mitochondrial and ATP metabolism. Therefore, DNA microarrays have revealed direct and indirect ta rgets, including internal feedback loops, through which N-glycosylation aff ects signaling and metabolic activities and is functionally linked with cel lular regulatory circuitry. (C) 2001 Academic Press.