RRC ID 32212
Author Furukawa N, Miyanaga A, Togawa M, Nakajima M, Taguchi H.
Title Diverse allosteric and catalytic functions of tetrameric d-lactate dehydrogenases from three Gram-negative bacteria.
Journal AMB Express
Abstract NAD-dependent d-lactate dehydrogenases (d-LDHs) reduce pyruvate into d-lactate with oxidation of NADH into NAD(+). Although non-allosteric d-LDHs from Lactobacilli have been extensively studied, the catalytic properties of allosteric d-LDHs from Gram-negative bacteria except for Escherichia coli remain unknown. We characterized the catalytic properties of d-LDHs from three Gram-negative bacteria, Fusobacterium nucleatum (FNLDH), Pseudomonas aeruginosa (PALDH), and E. coli (ECLDH) to gain an insight into allosteric mechanism of d-LDHs. While PALDH and ECLDH exhibited narrow substrate specificities toward pyruvate like usual d-LDHs, FNLDH exhibited a broad substrate specificity toward hydrophobic 2-ketoacids such as 2-ketobutyrate and 2-ketovalerate, the former of which gave a 2-fold higher k cat/S0.5 value than pyruvate. Whereas the three enzymes consistently showed hyperbolic shaped pyruvate saturation curves below pH 6.5, FNLDH and ECLDH, and PALDH showed marked positive and negative cooperativity, respectively, in the pyruvate saturation curves above pH 7.5. Oxamate inhibited the catalytic reactions of FNLDH competitively with pyruvate, and the PALDH reaction in a mixed manner at pH 7.0, but markedly enhanced the reactions of the two enzymes at low concentration through canceling of the apparent homotropic cooperativity at pH 8.0, although it constantly inhibited the ECLDH reaction. Fructose 1,6-bisphosphate and certain divalent metal ions such as Mg(2+) also markedly enhanced the reactions of FNLDH and PALDH, but none of them enhanced the reaction of ECLDH. Thus, our study demonstrates that bacterial d-LDHs have highly divergent allosteric and catalytic properties.
Volume 4
Pages 76
Published 2014-1-1
DOI 10.1186/s13568-014-0076-1
PII s13568-014-0076-1
PMID 25401076
PMC PMC4230899
IF 2.499
Times Cited 8
DNA material Genomic DNA of Pseudomonas aeruginosa JCM 14847 (JGD06292) Genomic DNA of Fusobacterium nucleatum subsp. nucleatum JCM 8532T (JGD08328).
General Microbes