title: Loss-of-Function Mutations in HspR Rescue the Growth Defect of a Mycobacterium tuberculosis Proteasome Accessory Factor E (pafE) Mutant.
abstract: Mycobacterium tuberculosisuses a proteasome to degrade proteins by both ATP-dependent and -independent pathways. While much has been learned about ATP-dependent degradation, relatively little is understood about the ATP-independent pathway, which is controlled byMycobacterium tuberculosisproteasomeaccessoryfactorE(PafE). Recently, we found that aMycobacterium tuberculosispafEmutant has slowed growthin vitroand is sensitive to killing by heat stress. However, we did not know if these phenotypes were caused by an inability to degrade the PafE-proteasome substrate HspR (heatshockproteinrepressor), an inability to degrade any damaged or misfolded proteins, or a defect in another protein quality control pathway. To address this question, we characterizedpafEsuppressor mutants that grew similarly topafE+bacteria under normal culture conditions. All but one suppressor mutant analyzed contained mutations that inactivated HspR function, demonstrating that the slowed growth and heat shock sensitivity of apafEmutant were caused primarily by the inability of the proteasome to degrade HspR.IMPORTANCEMycobacterium tuberculosisencodes a proteasome that is highly similar to eukaryotic proteasomes and is required for virulence. We recently discovered a proteasome cofactor, PafE, which is required for the normal growth, heat shock resistance, and full virulence ofM. tuberculosisIn this study, we demonstrate that PafE influences this phenotype primarily by promoting the expression of protein chaperone genes that are necessary for surviving proteotoxic stress.
authors.affiliation: Department of Microbiology, New York University School of Medicine, New York, New York, USA.
authors.forename: Jordan B
authors.initials: JB
authors.lastname: Jastrab
authors.affiliation: Department of Microbiology, New York University School of Medicine, New York, New York, USA.
authors.forename: Marie I
authors.initials: MI
authors.lastname: Samanovic
authors.affiliation: Department of Medicine, Division of Infectious Diseases, New York University School of Medicine, New York, New York, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Copin
authors.affiliation: Department of Microbiology, New York University School of Medicine, New York, New York, USA.|Department of Medicine, Division of Infectious Diseases, New York University School of Medicine, New York, New York, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Shopsin
authors.affiliation: Department of Microbiology, New York University School of Medicine, New York, New York, USA heran.darwin@med.nyu.edu.
authors.forename: K Heran
authors.initials: KH
authors.lastname: Darwin
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D006360:Heat-Shock Proteins; C108444:HspR protein, bacteria; C000612740:PafE protein, Mycobacterium tuberculosis; D012097:Repressor Proteins
keywords: Mycobacterium; heat shock; proteasome; proteostasis; tuberculosis