title: Structural Analysis of Mycobacterium tuberculosis Homologues of the Eukaryotic Proteasome Assembly Chaperone 2 (PAC2).
abstract: A previous bioinformatics analysis identified theMycobacterium tuberculosisproteins Rv2125 and Rv2714 as orthologs of the eukaryotic proteasome assembly chaperone 2 (PAC2). We set out to investigate whether Rv2125 or Rv2714 can function in proteasome assembly. We solved the crystal structure of Rv2125 at a resolution of 3.0 Å, which showed an overall fold similar to that of the PAC2 family proteins that include the archaeal PbaB and the yeast Pba1. However, Rv2125 and Rv2714 formed trimers, whereas PbaB forms tetramers and Pba1 dimerizes with Pba2. We also found that purified Rv2125 and Rv2714 could not bind toM. tuberculosis20S core particles. Finally, proteomic analysis showed that the levels of known proteasome components and substrate proteins were not affected by disruption of Rv2125 inM. tuberculosisOur work suggests that Rv2125 does not participate in bacterial proteasome assembly or function.IMPORTANCEAlthough many bacteria do not encode proteasomes,M. tuberculosisnot only uses proteasomes but also has evolved a posttranslational modification system called pupylation to deliver proteins to the proteasome. Proteasomes are essential forM. tuberculosisto cause lethal infections in animals; thus, determining how proteasomes are assembled may help identify new ways to combat tuberculosis. We solved the structure of a predicted proteasome assembly factor, Rv2125, and isolated a genetic Rv2125 mutant ofM. tuberculosisOur structural, biochemical, and genetic studies indicate that Rv2125 and Rv2714 do not function as proteasome assembly chaperones and are unlikely to have roles in proteasome biology in mycobacteria.
authors.affiliation: Cryo-EM Structural Biology Laboratory, Van Andel Research Institute, Grand Rapids, Michigan, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Bai
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 Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Marta
authors.initials: M
authors.lastname: Isasa
authors.affiliation: Graduate Program in Biochemistry and Structural Biology, Stony Brook University, Stony Brook, New York, USA.
authors.forename: Kuan
authors.initials: K
authors.lastname: Hu
authors.affiliation: Cryo-EM Structural Biology Laboratory, Van Andel Research Institute, Grand Rapids, Michigan, USA.
authors.forename: Hongjun
authors.initials: H
authors.lastname: Yu
authors.affiliation: Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Steven P
authors.initials: SP
authors.lastname: Gygi
authors.affiliation: Department of Microbiology, New York University School of Medicine, New York, New York, USA heran.darwin@med.nyu.edu huilin.li@vai.org.
authors.forename: K Heran
authors.initials: KH
authors.lastname: Darwin
authors.affiliation: Cryo-EM Structural Biology Laboratory, Van Andel Research Institute, Grand Rapids, Michigan, USA heran.darwin@med.nyu.edu huilin.li@vai.org.
authors.forename: Huilin
authors.initials: H
authors.lastname: Li
mesh_terms: D000818:Animals; D001105:Archaea / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009169:Mycobacterium tuberculosis / Q000235:genetics*; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D055503:Protein Multimerization; D040901:Proteomics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D018832:Molecular Chaperones; C559194:Pba1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D046988:Proteasome Endopeptidase Complex
keywords: Mycobacterium tuberculosis; proteasome; protein chaperone; structural biology