Tuberculosis (TB) remains one of the major health concerns worldwide. Mycobacterium tuberculosis (Mtb), the causative agent of TB, can flexibly change its metabolic processes during different life stages. Regulation of key metabolic enzyme activities by intracellular conditions, allosteric inhibition or feedback control can effectively contribute to Mtb survival under different conditions. Phosphofructokinase (Pfk) is one of the key enzymes regulating glycolysis. Mtb encodes two Pfk isoenzymes, Pfk A/Rv3010c and Pfk B/Rv2029c, which are differently expressed upon transition to the hypoxia-induced non-replicating state of the bacteria. While pfkB gene and protein expression are upregulated under hypoxic conditions, Pfk A levels decrease. Here, we present biochemical characterization of both Pfk isoenzymes, revealing that Pfk A and Pfk B display different kinetic properties. Although the glycolytic activity of Pfk A is higher than that of Pfk B, it is markedly inhibited by an excess of both substrates (fructose-6-phosphate and ATP), reaction products (fructose-1,6-bisphosphate and ADP) and common metabolic allosteric regulators. In contrast, synthesis of fructose-1,6-bisphosphatase catalyzed by Pfk B is not regulated by higher levels of substrates, and metabolites. Importantly, we found that only Pfk B can catalyze the reverse gluconeogenic reaction. Pfk B thus can support glycolysis under conditions inhibiting Pfk A function.

• Keywords
• Mycobacterium tuberculosis, allosteric regulation, enzyme kinetics, glycolysis, phosphofructokinase A and B,
• MeSH
• Adenosine Diphosphate metabolism   pharmacology   MeSH
• Adenosine Triphosphate metabolism   pharmacology   MeSH
• Allosteric Regulation MeSH
• Bacterial Proteins antagonists & inhibitors   metabolism   MeSH
• Enzyme Induction MeSH
• Phosphofructokinases antagonists & inhibitors   metabolism   MeSH
• Fructosediphosphates biosynthesis   pharmacology   MeSH
• Fructosephosphates metabolism   pharmacology   MeSH
• Gluconeogenesis MeSH
• Glycolysis MeSH
• Hexosephosphates metabolism   MeSH
• Isoenzymes antagonists & inhibitors   metabolism   MeSH
• Catalysis MeSH
• Kinetics MeSH
• Oxygen pharmacology   MeSH
• L-Lactate Dehydrogenase metabolism   MeSH
• Mycobacterium tuberculosis drug effects   enzymology   MeSH
• Pyruvate Kinase metabolism   MeSH
• Recombinant Proteins metabolism   MeSH
• Substrate Specificity MeSH
• Feedback, Physiological MeSH
• Publication type
• Journal Article MeSH
• Comparative Study MeSH
• Names of Substances
• Adenosine Diphosphate MeSH
• Adenosine Triphosphate MeSH
• Bacterial Proteins MeSH
• Phosphofructokinases MeSH
• fructose-1,6-diphosphate MeSH Browser
• fructose-6-phosphate MeSH Browser
• Fructosediphosphates MeSH
• Fructosephosphates MeSH
• Hexosephosphates MeSH
• Isoenzymes MeSH
• Oxygen MeSH
• L-Lactate Dehydrogenase MeSH
• phosphofructokinase A protein, Mycobacterium tuberculosis MeSH Browser
• Pyruvate Kinase MeSH
• Recombinant Proteins MeSH
• tagatose 6-phosphate MeSH Browser