Blm3 is part of nascent proteasomes and is involved in a late stage of nuclear proteasome assembly.
Proteasomes are multisubunit proteases that are responsible for regulated proteolysis. The degradation of the proteasomal maturation factor, named Ump1 in yeast, completes the autocatalytic processing of inactive precursor complexes into the proteolytically active core particle (CP) of the proteasome. We have identified Blm3, a conserved nuclear protein, as a new component of Ump1-associated precursor complexes. A lack of Blm3 resulted in an increased rate of precursor processing and an accelerated turnover of Ump1, which suggests that Blm3 prevents premature activation of proteasomal CPs. On the basis of biochemical fractionation experiments combined with in vivo localization studies, we propose that Blm3 joins nascent CPs inside the nucleus to coordinate late stages of proteasome assembly in yeast.
Fehlker
Marion
M
Institut für Biochemie, Humboldt Universität zu Berlin, Universitätsklinikum Charité, Monbijoustrasse 2, D-10117 Berlin, Germany.
Wendler
Petra
P
Lehmann
Andrea
A
Enenkel
Cordula
C
D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000378:metabolism*; D010450:Endopeptidases; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism; D009097:Multienzyme Complexes / Q000737:chemistry / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D011498:Protein Precursors / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D013347:Subcellular Fractions / Q000737:chemistry / Q000378:metabolism
D046911:Macromolecular Substances; D008565:Membrane Proteins; D018832:Molecular Chaperones; D009097:Multienzyme Complexes; D009687:Nuclear Proteins; D011498:Protein Precursors; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C110856:proteasome maturation protein; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; C101111:UBP3 protein, S cerevisiae