title: Sequence, expression, and function of the gene for the nonphosphorylating, NADP-dependent glyceraldehyde-3-phosphate dehydrogenase of Streptococcus mutans.
abstract: We report the sequencing of a 2,019-bp region of the Streptococcus mutans NG5 genome which contains a 1,428-bp open reading frame (ORF) whose putative translation product had 50% identity to the amino acid sequences of the nonphosphorylating, NADP-dependent glyceraldehyde-3-phosphate dehydrogenases (GAPN) from maize and pea. This ORF is located approximately 200 bp downstream of the ptsI gene coding for enzyme I of the phosphoenolpyruvate:sugar phosphotransferase transport system. Mutant BCH150, in which the putative gapN gene had been inactivated, lacked GAPN activity that was present in the wild-type strain, thus positively identifying the ORF as the S. mutans gapN gene. Another strain of S. mutans, DC10, which contains an insertionally inactivated ptsI gene, still possessed GAPN activity, as did S. salivarius ATCC 25975, which contains an insertion element between the ptsI and gapN genes. Since the wild-type S. mutans NG5 lacks both glucose-6-phosphate dehydrogenase and NADH:NADP oxidoreductase activities, the NADP-dependent glyceraldehyde-3-phosphate dehydrogenase is important as a means of generating NADPH for biosynthetic reactions.
authors.affiliation: Department of Oral Biology, University of Manitoba, Winnipeg, Canada.
authors.forename: D A
authors.initials: DA
authors.lastname: Boyd
authors.forename: D G
authors.initials: DG
authors.lastname: Cvitkovitch
authors.forename: I R
authors.initials: IR
authors.lastname: Hamilton
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics*; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D016366:Open Reading Frames / Q000235:genetics; D018532:Pisum sativum / Q000201:enzymology / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013295:Streptococcus mutans / Q000201:enzymology / Q000235:genetics*; D003313:Zea mays / Q000201:enzymology / Q000235:genetics
chemical_list: D011994:Recombinant Proteins; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases