Lactate dehydrogenase of Streptococcus mutans (LDH)

Lactate dehydrogenase of Streptococcus mutans is a cytoplasmic enzyme (EC 1.1.1.27) crucial for the fermentation pathway, catalyzing the reduction of pyruvate to lactate using NADH as a cofactor and thus regenerating NAD+ for continued glycolysis[3][7]. The enzyme is allosterically activated by fructose-1,6-bisphosphate and is a central determinant of S. mutans acidogenicity, contributing directly to dental caries pathogenesis by increasing local acidification and enamel demineralization[3][4][6]. LDH is considered a key virulence factor; mutants deficient in LDH show severely diminished cariogenic ability and can even outcompete wild-type strains in plaque formation but with reduced acid production and caries potential[5]. The enzyme is subject to post-translational regulation such as lysine acetylation (negatively regulating its activity), underscoring its essentiality in metabolic adaptation and virulence expression in response to environmental cues[1][2].

Other names

S. mutans LDHL-lactate dehydrogenase (EC 1.1.1.27)

Enzyme inhibitors (decrease LDH activity to reduce lactic acid production, thus decreasing virulence/cariogenicity of S. mutans)[1]. Allosteric regulators (e.g., fructose-1,6-bisphosphate serves as an allosteric activator, required for maximal enzymatic activity)[3][6][7].