TAILIEUCHUNG - Báo cáo khoa học: Mycobacterium tuberculosis possesses a functional enzyme for the synthesis of vitamin C, L-gulono-1,4-lactone dehydrogenase

The last step of the biosynthesis ofl-ascorbic acid (vitamin C) in plants and animals is catalyzed by l-gulono-1,4-lactone oxidoreductases, which use bothl-gulono-1,4-lactone and l-galactono-1,4-lactone as substrates. l-Gul-ono-1,4-lactone oxidase is missing in scurvy-prone, vitamin C-deficient ani-mals, such as humans and guinea pigs, which are also highly susceptible to tuberculosis. | ỊFEBS Journal Mycobacterium tuberculosis possesses a functional enzyme for the synthesis of vitamin C L-gulono-1 4-lactone dehydrogenase Beata A. Wolucka1 and David Communi2 1 Laboratory of MycobacterialBiochemistry Pasteur Institute of Brussels Institute of Public Health Belgium 2 Institute of Interdisciplinary Research IRIBHM Faculty of Medicine Free University of Brussels Belgium Keywords ascorbic acid biosynthesis L-gulonolactone oxidase tuberculosis vitamin C Correspondence B. A. Wolucka Laboratory of Mycobacterial Biochemistry Pasteur Institute of Brussels 642 Engeland Street B-1180 Brussels Belgium Fax 32 2 373 3282 Tel 32 2 373 3100 E-mail bwolucka@ Received 21 June 2006 accepted 31 July 2006 doi The last step of the biosynthesis of L-ascorbic acid vitamin C in plants and animals is catalyzed by L-gulono-1 4-lactone oxidoreductases which use both L-gulono-1 4-lactone and L-galactono-1 4-lactone as substrates. L-Gul-ono-1 4-lactone oxidase is missing in scurvy-prone vitamin C-deficient animals such as humans and guinea pigs which are also highly susceptible to tuberculosis. A BLAST search using the rat L-gulono-1 4-lactone oxidase sequence revealed the presence of closely related orthologs in a limited number of bacterial species including several pathogens of human lungs such as Mycobacterium tuberculosis Pseudomonas aeruginosa Burkholderia cepacia and Bacillus anthracis. The genome of M. tuberculosis the etiologic agent of tuberculosis encodes a protein Rv1771 that shows 32 identity with the rat L-gulono-1 4-lactone oxidase protein. The Rv1771 gene was cloned and expressed in Escherichia coli and the corresponding protein was affinity-purified and characterized. The FAD-binding motif-containing Rv1771 protein is a metalloenzyme that oxidizes L-gulono-1 4-lactone Km mm but not L-galactono-1 4-lactone. The enzyme has a dehydrogenase activity and can use both cytochrome c Km pm and phenazine methosulfate as .

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