title: Mycobacterium tuberculosisProteasome Accessory Factor A (PafA) Can Transfer Prokaryotic Ubiquitin-Like Protein (Pup) between Substrates.
abstract: The protein degradation machinery ofMycobacterium tuberculosisincludes a proteasome and a ubiquitin-like protein (Pup). Proteasome accessory factor A (PafA) attaches Pup to proteins to target them for degradation by the proteasome. Free Pup is unstable and never observed in extracts ofM. tuberculosis, an observation that led us to hypothesize that PafA may need alternative sources of Pup. Here, we show that PafA can move Pup from one proteasome substrate, inositol 1-phosphate synthetase (Ino1), to two different proteins, malonyl coenzyme A (CoA)-acyl carrier protein transacylase (FabD) and lonely guy (Log). This apparent "transpupylation" reaction required a previously unrecognized depupylase activity in PafA, and, surprisingly, this depupylase activity was much more efficient than the activity of the dedicated depupylase Dop (deamidase of Pup). Thus, PafA can potentially use both newly synthesized Pup and recycled Pup to doom proteins for degradation.IMPORTANCEUnlike eukaryotes, which contain hundreds of ubiquitin ligases, Pup-containing bacteria appear to have a single ligase to pupylate dozens if not hundreds of different proteins. The observation that PafA can depupylate and transpupylatein vitrooffers new insight into how protein stability is regulated in proteasome-bearing bacteria. Importantly, PafA and the dedicated depupylase Dop are each required for the full virulence ofMycobacterium tuberculosisThus, inhibition of both enzymes may be extremely attractive for the development of therapeutics against tuberculosis.
authors.affiliation: Department of Microbiology, New York University School of Medicine, New York, New York, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Microbiology, New York University School of Medicine, New York, New York, USA.
authors.forename: Kristin E
authors.initials: KE
authors.lastname: Burns-Huang
authors.affiliation: Department of Chemical Immunology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Guido V
authors.initials: GV
authors.lastname: Janssen
authors.affiliation: Van Andel Research Institute, Grand Rapids, Michigan, USA.
authors.forename: Huilin
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Chemical Immunology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Huib
authors.initials: H
authors.lastname: Ovaa
authors.affiliation: Departments of Biology and Chemistry, Brandeis University, Waltham, Massachusetts, USA.
authors.forename: Lizbeth
authors.initials: L
authors.lastname: Hedstrom
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 / Q000378:metabolism*; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D014166:Transferases / Q000378:metabolism*; D014452:Ubiquitins / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C533288:Pup protein, Mycobacterium tuberculosis; D014452:Ubiquitins; D014166:Transferases; D046988:Proteasome Endopeptidase Complex