Response to reactive nitrogen intermediates in Mycobacterium tuberculosis: induction of the 16-kilodalton alpha-crystallin homolog by exposure to nitric oxide donors.
In contrast to the apparent paucity of Mycobacterium tuberculosis response to reactive oxygen intermediates, this organism has evolved a specific response to nitric oxide challenge. Exposure of M. tuberculosis to NO donors induces the synthesis of a set of polypeptides that have been collectively termed Nox. In this work, the most prominent Nox polypeptide, Nox16, was identified by immunoblotting and by N-terminal sequencing as the alpha-crystallin-related, 16-kDa small heat shock protein, sHsp16. A panel of chemically diverse donors of nitric oxide, with the exception of nitroprusside, induced sHsp16 (Nox16). Nitroprusside, a coordination complex of Fe2+ with a nitrosonium (NO+) ion, induced a 19-kDa polypeptide (Nox19) homologous to the nonheme bacterial ferritins. We conclude that the NO response in M. tuberculosis is dominated by increased synthesis of the alpha-crystallin homolog sHsp16, previously implicated in stationary-phase processes and found in this study to be a major M. tuberculosis protein induced upon exposure to reactive nitrogen intermediates.
Garbe
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Department of Microbiology and Immunology, University of Texas Health Science Center San Antonio 78284, USA.
Hibler
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Deretic
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D000595:Amino Acid Sequence; D000942:Antigens, Bacterial / Q000737:chemistry; D003459:Crystallins / Q000096:biosynthesis* / Q000737:chemistry; D005293:Ferritins / Q000737:chemistry; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D006360:Heat-Shock Proteins / Q000737:chemistry; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000378:metabolism / Q000494:pharmacology*; D017386:Sequence Homology, Amino Acid
D000942:Antigens, Bacterial; D003459:Crystallins; D006360:Heat-Shock Proteins; D020030:Nitric Oxide Donors; D009569:Nitric Oxide; D005293:Ferritins