Functionally important amino acids in Saccharomyces cerevisiae aspartate kinase.
Saccharomyces cerevisiae aspartate kinase (AK(Sc)) phosphorylates L-Asp as the first step in the aspartate pathway responsible for the biosynthesis of L-Thr, L-Met, and L-Ile in microorganisms and plants. Using site-directed mutagenesis, we have evaluated the importance of residues in AK(Sc) that are strongly conserved among aspartate kinases or in other small molecule kinases. Steady state kinetic analysis of the purified AK(Sc) variants reveals that several of the targeted amino acids, particularly K18 and H292, have important roles in the enzymatic reaction. These results provide the first identification of amino acid residues crucial to the action of this important metabolic enzyme.
Bareich
David C
DC
Department of Biochemistry, McMaster University, 1200 Main St, W, Hamilton, Ont, Canada L8N 3Z5.
Wright
Gerard D
GD
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D001222:Aspartate Kinase / Q000737:chemistry* / Q000235:genetics; D001224:Aspartic Acid / Q000737:chemistry; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000378:metabolism; D006639:Histidine / Q000737:chemistry; D007532:Isoleucine / Q000737:chemistry; D007700:Kinetics; D008715:Methionine / Q000737:chemistry; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid; D013912:Threonine / Q000737:chemistry
D000596:Amino Acids; D007532:Isoleucine; D013912:Threonine; D001224:Aspartic Acid; D006639:Histidine; D008715:Methionine; D001222:Aspartate Kinase