Differential roles for the Co2+/Ni2+ transporting ATPases, CtpD and CtpJ, in Mycobacterium tuberculosis virulence

Authors

  • Daniel Raimunda,

    1. Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA, USA
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    • Both authors contributed equally to this work.
  • Jarukit E. Long,

    1. Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, USA
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    • Both authors contributed equally to this work.
  • Teresita Padilla-Benavides,

    1. Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA, USA
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  • Christopher M. Sassetti,

    1. Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, USA
    2. Howard Hughes Medical Institute, Chevy Chase, MD, USA
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  • José M. Argüello

    Corresponding author
    1. Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA, USA
    • For correspondence. E-mail arguello@wpi.edu; Tel. (+1) 508 831 5326; Fax (+1) 508 831 4116.

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Summary

The genome of Mycobacterium tuberculosis encodes two paralogous P1B4-ATPases, CtpD (Rv1469) and CtpJ (Rv3743). Both proteins showed ATPase activation by Co2+ and Ni2+, and both appear to be required for metal efflux from the cell. However, using a combination of biochemical and genetic studies we found that these proteins play non-redundant roles in virulence and metal efflux. CtpJ expression is induced by Co2+ and this protein possesses a relatively high turnover rate. A ctpJ deletion mutant accumulated Co2+, indicating that this ATPase controls cytoplasmic metal levels. In contrast, CtpD expression is induced by redox stressors and this protein displays a relatively low turnover rate. A ctpD mutant failed to accumulate metal, suggesting an alternative cellular function. ctpD is cotranscribed with two thioredoxin genes trxA (Rv1470), trxB (Rv1471), and an enoyl-coA hydratase (Rv1472), indicating a possible role for CtpD in the metallation of these redox-active proteins. Supporting this, in vitro metal binding assays showed that TrxA binds Co2+ and Ni2+. Mutation of ctpD, but not ctpJ, reduced bacterial fitness in the mouse lung, suggesting that redox maintenance, but not Co2+ accumulation, is important for growth in vivo.

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