title: Identification of substrates of the Mycobacterium tuberculosis proteasome.
abstract: The putative proteasome-associated proteins Mpa (Mycobaterium proteasomal ATPase) and PafA (proteasome accessory factor A) of the human pathogen Mycobacterium tuberculosis (Mtb) are essential for virulence and resistance to nitric oxide. However, a direct link between the proteasome protease and Mpa or PafA has never been demonstrated. Furthermore, protein degradation by bacterial proteasomes in vitro has not been accomplished, possibly due to the failure to find natural degradation substrates or other necessary proteasome co-factors. In this work, we identify the first bacterial proteasome substrates, malonyl Co-A acyl carrier protein transacylase and ketopantoate hydroxymethyltransferase, enzymes that are required for the biosynthesis of fatty acids and polyketides that are essential for the pathogenesis of Mtb. Maintenance of the physiological levels of these enzymes required Mpa and PafA in addition to proteasome protease activity. Mpa levels were also regulated in a proteasome-dependent manner. Finally, we found that a conserved tyrosine of Mpa was essential for function. Thus, these results suggest that Mpa, PafA, and the Mtb proteasome degrade bacterial proteins that are important for virulence in mice.
authors.affiliation: Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Pearce
authors.forename: Pooja
authors.initials: P
authors.lastname: Arora
authors.forename: Richard A
authors.initials: RA
authors.lastname: Festa
authors.forename: Susan M
authors.initials: SM
authors.lastname: Butler-Wu
authors.forename: Rajesh S
authors.initials: RS
authors.lastname: Gokhale
authors.forename: K Heran
authors.initials: KH
authors.lastname: Darwin
mesh_terms: D051080:Acyl-Carrier Protein S-Malonyltransferase / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D019877:Hydroxymethyl and Formyl Transferases / Q000378:metabolism*; D051379:Mice; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000201:enzymology*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D014397:Tuberculosis, Pulmonary / Q000201:enzymology / Q000382:microbiology
chemical_list: D001426:Bacterial Proteins; D019877:Hydroxymethyl and Formyl Transferases; C021477:3-methyl-2-oxobutanoate hydroxymethyltransferase; D051080:Acyl-Carrier Protein S-Malonyltransferase; D000469:Alkaline Phosphatase; C449204:periplasmic alkaline phosphatase, Chryseobacterium meningosepticum; D046988:Proteasome Endopeptidase Complex; D000251:Adenosine Triphosphatases; C479920:Mpa protein, Mycobacterium tuberculosis