title: Characterization of a Mycobacterium tuberculosis proteasomal ATPase homologue.
abstract: 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.
authors.affiliation: Department of Microbiology and Immunology, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021, USA. heran.darwin@med.nyu.edu
authors.forename: K Heran
authors.initials: KH
authors.lastname: Darwin
authors.forename: Gang
authors.initials: G
authors.lastname: Lin
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Chen
authors.forename: Huilin
authors.initials: H
authors.lastname: Li
authors.forename: Carl F
authors.initials: CF
authors.lastname: Nathan
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D020285:Cryoelectron Microscopy; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity*; D017354:Point Mutation; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D026361:Reactive Nitrogen Species / Q000494:pharmacology*; D014397:Tuberculosis, Pulmonary / Q000382:microbiology / Q000401:mortality / Q000503:physiopathology
chemical_list: D021122:Protein Subunits; D026361:Reactive Nitrogen Species; D046988:Proteasome Endopeptidase Complex; D000251:Adenosine Triphosphatases; C479920:Mpa protein, Mycobacterium tuberculosis