title: Structural analysis of the dodecameric proteasome activator PafE in Mycobacterium tuberculosis.
abstract: The human pathogen Mycobacterium tuberculosis (Mtb) requires a proteasome system to cause lethal infections in mice. We recently found that proteasome accessory factor E (PafE, Rv3780) activates proteolysis by the Mtb proteasome independently of adenosine triphosphate (ATP). Moreover, PafE contributes to the heat-shock response and virulence of Mtb Here, we show that PafE subunits formed four-helix bundles similar to those of the eukaryotic ATP-independent proteasome activator subunits of PA26 and PA28. However, unlike any other known proteasome activator, PafE formed dodecamers with 12-fold symmetry, which required a glycine-XXX-glycine-XXX-glycine motif that is not found in previously described activators. Intriguingly, the truncation of the PafE carboxyl-terminus resulted in the robust binding of PafE rings to native proteasome core particles and substantially increased proteasomal activity, suggesting that the extended carboxyl-terminus of this cofactor confers suboptimal binding to the proteasome core particle. Collectively, our data show that proteasomal activation is not limited to hexameric ATPases in bacteria.
authors.affiliation: Biosciences Department, Brookhaven National Laboratory, Upton, NY 11973;
authors.forename: Lin
authors.initials: L
authors.lastname: Bai
authors.affiliation: Biosciences Department, Brookhaven National Laboratory, Upton, NY 11973; Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794;
authors.forename: Kuan
authors.initials: K
authors.lastname: Hu
authors.affiliation: Biosciences Department, Brookhaven National Laboratory, Upton, NY 11973;
authors.forename: Tong
authors.initials: T
authors.lastname: Wang
authors.affiliation: Department of Microbiology, New York University School of Medicine, New York, NY 10016.
authors.forename: Jordan B
authors.initials: JB
authors.lastname: Jastrab
authors.affiliation: Department of Microbiology, New York University School of Medicine, New York, NY 10016 heran.darwin@med.nyu.edu hli@bnl.gov.
authors.forename: K Heran
authors.initials: KH
authors.lastname: Darwin
authors.affiliation: Biosciences Department, Brookhaven National Laboratory, Upton, NY 11973; Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794; heran.darwin@med.nyu.edu hli@bnl.gov.
authors.forename: Huilin
authors.initials: H
authors.lastname: Li
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D018360:Crystallography, X-Ray; D018869:Heat-Shock Response; D006801:Humans; D051379:Mice; D009169:Mycobacterium tuberculosis / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000378:metabolism*; D014376:Tuberculosis / Q000382:microbiology / Q000473:pathology*
chemical_list: D001426:Bacterial Proteins; C000612740:PafE protein, Mycobacterium tuberculosis; D021122:Protein Subunits; D046988:Proteasome Endopeptidase Complex; D000251:Adenosine Triphosphatases
keywords: Mycobacterium tuberculosis; X-ray crystallography; cryo-EM; proteasome; structural biology