title: Ubiquitin-Like Proteasome System Represents a Eukaryotic-Like Pathway for Targeted Proteolysis in Archaea.
abstract: The molecular mechanisms of targeted proteolysis in archaea are poorly understood, yet they may have deep evolutionary roots shared with the ubiquitin-proteasome system of eukaryotic cells. Here, we demonstrate in archaea that TBP2, a TATA-binding protein (TBP) modified by ubiquitin-like isopeptide bonds, is phosphorylated and targeted for degradation by proteasomes. Rapid turnover of TBP2 required the functions of UbaA (the E1/MoeB/ThiF homolog of archaea), AAA ATPases (Cdc48/p97 and Rpt types), a type 2 JAB1/MPN/MOV34 metalloenzyme (JAMM/MPN+) homolog (JAMM2), and 20S proteasomes. The ubiquitin-like protein modifier small archaeal modifier protein 2 (SAMP2) stimulated the degradation of TBP2, but SAMP2 itself was not degraded. Analysis of the TBP2 fractions that were not modified by ubiquitin-like linkages revealed that TBP2 had multiple N termini, including Met1-Ser2, Ser2, and Met1-Ser2(p) [where (p) represents phosphorylation]. The evidence suggested that the Met1-Ser2(p) form accumulated in cells that were unable to degrade TBP2. We propose a model in archaea in which the attachment of ubiquitin-like tags can target proteins for degradation by proteasomes and be controlled by N-terminal degrons. In support of a proteolytic mechanism that is energy dependent and recycles the ubiquitin-like protein tags, we find that a network of AAA ATPases and a JAMM/MPN+ metalloprotease are required, in addition to 20S proteasomes, for controlled intracellular proteolysis.
  
  
  
  This study advances the fundamental knowledge of signal-guided proteolysis in archaea and sheds light on components that are related to the ubiquitin-proteasome system of eukaryotes. In archaea, the ubiquitin-like proteasome system is found to require function of an E1/MoeB/ThiF homolog, a type 2 JAMM/MPN+ metalloprotease, and a network of AAA ATPases for the targeted destruction of proteins. We provide evidence that the attachment of the ubiquitin-like protein is controlled by an N-terminal degron and stimulates proteasome-mediated proteolysis.
authors.affiliation: Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, USA.
authors.forename: Xian
authors.initials: X
authors.lastname: Fu
authors.affiliation: Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, USA College of Food Science and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Liu
authors.affiliation: Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, USA.
authors.forename: Iona
authors.initials: I
authors.lastname: Sanchez
authors.affiliation: Proteomics and Mass Spectrometry, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, Florida, USA.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Silva-Sanchez
authors.affiliation: Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, USA.
authors.forename: Nathaniel L
authors.initials: NL
authors.lastname: Hepowit
authors.affiliation: Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, USA.
authors.forename: Shiyun
authors.initials: S
authors.lastname: Cao
authors.affiliation: Proteomics and Mass Spectrometry, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, Florida, USA Department of Biology, College of Liberal Arts and Sciences, University of Florida, Gainesville, Florida, USA Genetics Institute, University of Florida, Gainesville, Florida, USA.
authors.forename: Sixue
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, USA Genetics Institute, University of Florida, Gainesville, Florida, USA jmaupin@ufl.edu.
authors.forename: Julie
authors.initials: J
authors.lastname: Maupin-Furlow
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D001105:Archaea / Q000235:genetics* / Q000378:metabolism*; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003593:Cytoplasm / Q000737:chemistry / Q000378:metabolism*; D009154:Mutation; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D059748:Proteolysis; D035181:TATA-Box Binding Protein / Q000378:metabolism*; D025801:Ubiquitin / Q000235:genetics / Q000378:metabolism*
chemical_list: D019843:Archaeal Proteins; D035181:TATA-Box Binding Protein; D025801:Ubiquitin; D046988:Proteasome Endopeptidase Complex; D000251:Adenosine Triphosphatases