Open AccessCellular responses to L ‐serine in S accharomyces cerevisiae : roles of general amino acid control, compartmentalization, and aspartate synthesis
Author(s) -
Lee Johnny C.Y.,
Tsoi Abraham,
Kornfeld Geoffrey D.,
Dawes Ian W.
Publication year - 2013
Publication title -
fems yeast research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.991
H-Index - 92
eISSN - 1567-1364
pISSN - 1567-1356
DOI - 10.1111/1567-1364.12063
Subject(s) - serine , biology , biochemistry , amino acid , amino acid synthesis , glycine , threonine , compartmentalization (fire protection) , saccharomyces cerevisiae , ribosome biogenesis , metabolism , glycine cleavage system , stringent response , ribosome , rna , phosphorylation , yeast , gene , mutant , enzyme , lysine
In addition to its other roles, l ‐serine functions in one‐carbon metabolism and is interconvertable with glycine via serine hydroxymethyltransferases. However, the transcriptional response by S accharomyces cerevisiae to l ‐serine addition is markedly different from that to glycine, with l ‐serine acting as a nutrient source rather than one‐carbon units. Following addition of excess l ‐serine, 743 genes showed significant expression changes. Induced functions included amino acid synthesis, some stress responses, and F e S metabolism, while ribosomal RNA processing, ribosome biogenesis and hexose transport were repressed. A co‐regulated network of ten transcription factors could together control more than 90% of the induced and repressed genes forming a general response to changes induced by other amino acids or stresses and including the general amino acid control system usually activated in response to starvation for amino acids. A specific response to l ‐serine was induction of CHA1 encoding serine (threonine) dehydratase. l ‐serine addition resulted in a substantial transient increase in l ‐aspartate, which is, rather than l ‐glutamate, the major metabolite for short‐term storage of ammonia derived from degradation of l ‐serine. l ‐aspartate synthesis was exclusively through mitochondrial metabolism of l ‐serine to pyruvate and ammonia, involving C ha1p, cytoplasmic pyruvate carboxylases P yc1p and P yc2p, and the cytoplasmic aspartate aminotransferase A at2p.