A novel L-serine deaminase activity in Escherichia coli K-12.
We demonstrate here that Escherichia coli K-12 synthesizes two different L-serine deaminases (L-SD) catalyzing the nonoxidative deamination of L-serine to pyruvate, one coded for by the previously described sdaA gene and a second, hitherto undescribed enzyme which we call L-SD2. A strain carrying a null mutation in sdaA made no detectable L-SD in minimal medium, but had activity in Luria broth. We describe a mutation, sdaX, which affects the regulation of L-SD2 and permits its expression in minimal medium, and an insertion mutation, sdaB, which abolishes L-SD2 activity completely. Both mutations lie near 60.5 min on the E. coli genetic map. The two L-SD enzymes have similar enzyme parameters, and both require posttranslational activation.
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Department of Biological Sciences, Concordia University, Montreal, Quebec, Canada.
Newman
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D002874:Chromosome Mapping; D003001:Cloning, Molecular; D003227:Conjugation, Genetic; D004229:Dithiothreitol / Q000494:pharmacology; D004926:Escherichia coli / Q000378:metabolism*; D007501:Iron / Q000494:pharmacology; D012695:L-Serine Dehydratase / Q000096:biosynthesis* / Q000235:genetics; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D014161:Transduction, Genetic
D007501:Iron; D012695:L-Serine Dehydratase; D004229:Dithiothreitol