Glycolytic and Non-glycolytic Functions of Mycobacterium tuberculosis Fructose-1,6-bisphosphate Aldolase, an Essential Enzyme Produced by Replicating and Non-replicating Bacilli

SANTANGELO, MARÌA DE LA PAZ; PETRA M. GEST; MARCELO E. GUERIN; MATHIEU COINÇON; HA PHAM; GAVIN RYAN; SUSAN E. PUCKETT; JOHN S. SPENCER; MERCEDES GONZALEZ-JUARRERO; RACHA DAHER; ANNE J. LENAERTS; DIRK SCHNAPPINGER; MICHEL THERISOD; SABINE EHRT; JURGEN SYGUSCH; MARY JACKSON

JOURNAL OF BIOLOGICAL CHEMISTRY

AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Lugar: Bethesda, Maryland; Año: 2011 vol. 286 p. 40219 - 40231

0021-9258

The search for antituberculosis drugs active against persistent bacilli has led to our interest in metallodependent class II fruc- tose-1,6-bisphosphate aldolase (FBA-tb), a key enzyme of gluco- neogenesis absent from mammalian cells. Knock-out experi- ments at the fba-tb locus indicated that this gene is required for the growth of Mycobacterium tuberculosis on gluconeogenetic substrates and in glucose-containing medium. Surface labeling and enzymatic activity measurements revealed that this enzyme was exported to the cell surface of M. tuberculosis and produced under various axenic growth conditions including oxygen depletion and hence by non-replicating bacilli. Importantly, FBA-tb was also produced in vivo in the lungs of infected guinea pigs and mice. FBA-tb bound human plasmin(ogen) and pro- tected FBA-tb-bound plasmin from regulation by 􏰅2-antiplas- min, suggestive of an involvement of this enzyme in host/patho- gen interactions. The crystal structures of FBA-tb in the native form and in complex with a hydroxamate substrate analog were determined to 2.35- and 1.9-Å resolution, respectively. Whereas inhibitor attachment had no effect on the plasminogen binding activity of FBA-tb, it competed with the natural substrate of the enzyme, fructose 1,6-bisphosphate, and substantiated a previ- ously unknown reaction mechanism associated with metallode- pendent aldolases involving recruitment of the catalytic zinc ion by the substrate upon active site binding. Altogether, our results highlight the potential of FBA-tb as a novel therapeutic target against both replicating and non-replicating bacilli.