Characterization of a Mycobacterium tuberculosis proteasomal ATPase homologue

• Published in: Molecular microbiology 2005-01, Vol.55 (2), p.561-571
• Main Authors: Darwin, K. Heran, Lin, Gang, Chen, Zhiqiang, Li, Huilin, Nathan, Carl F.
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphatases - chemistry; Adenosine Triphosphatases - genetics; Adenosine Triphosphatases - metabolism; Animals; Bacterial proteins; Biological and medical sciences; Cryoelectron Microscopy; Enzymes; Fundamental and applied biological sciences. Psychology; Humans; Mice; Mice, Inbred BALB C; Microbiology; Molecular biology; Mutation; Mycobacterium tuberculosis; Mycobacterium tuberculosis - drug effects; Mycobacterium tuberculosis - enzymology; Mycobacterium tuberculosis - genetics; Mycobacterium tuberculosis - pathogenicity; Point Mutation; Proteasome Endopeptidase Complex - genetics; Proteasome Endopeptidase Complex - metabolism; Protein Subunits - chemistry; Protein Subunits - genetics; Protein Subunits - metabolism; Reactive Nitrogen Species - pharmacology; Rodents; Tuberculosis; Tuberculosis, Pulmonary - microbiology; Tuberculosis, Pulmonary - mortality; Tuberculosis, Pulmonary - physiopathology
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/j.1365-2958.2004.04403.x

Summary A screen for Mycobacterium tuberculosis (Mtb) mutants sensitive to reactive nitrogen intermediates identified transposon insertions in the presumptive proteasomal ATPase gene mpa (mycobacterium proteasome ATPase; Rv2115c). mpa mutants are attenuated in both wild type and nitric oxide synthase 2 deficient mice. In this work, we show that attenuation of mpa mutants is severe, and that Mpa is an ATPase associated with various cellular activities (AAA) ATPase that forms hexameric rings resembling the eukaryotic complex p97/valosin‐containing protein (VCP). Point mutations in the conserved Walker box ATPase motifs of Mpa greatly reduced or abolished ATPase activity in vitro and abrogated protection of Mtb against acidified nitrite. A mutant Mpa protein missing only its last two amino acids retained ATPase activity, yet failed to protect Mtb against nitrite. The corresponding strain was attenuated in mice. Thus, Mpa is an ATPase whose enzymatic activity is necessary but not sufficient to protect against reactive nitrogen intermediates.