The cellular level of PR500, a protein complex related to the 19S regulatory particle of the proteasome, is regulated in response to stresses in plants.
In Arabidopsis seedlings and cauliflower florets, Rpn6 (a proteasome non-ATPase regulatory subunit) was found in two distinct protein complexes of approximately 800 and 500 kDa, respectively. The large complex likely represents the proteasome 19S regulator particle (RP) because it displays the expected subunit composition and all characteristics. The small complex, designated PR500, shares at least three subunits with the "lid" subcomplex of 19S RP and is loosely associated with an hsp70 protein. In Arabidopsis COP9 signalosome mutants, PR500 was specifically absent or reduced to an extent that correlates with the severity of the mutations. Furthermore, PR500 was also diminished in response to potential protein-misfolding stresses caused by the heat shock and canavanine treatment. Immunofluorescence studies suggest that PR500 has a distinct localization pattern and is enriched in specific nuclear foci. We propose that PR500 may be evolved in higher plants to cope with the frequently encountered environmental stresses.
Peng
Z
Z
Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104, USA.
Staub
J M
JM
Serino
G
G
Kwok
S F
SF
Kurepa
J
J
Bruce
B D
BD
Vierstra
R D
RD
Wei
N
N
Deng
X W
XW
D017360:Arabidopsis / Q000187:drug effects / Q000502:physiology*; D001937:Brassica / Q000378:metabolism; D000075686:COP9 Signalosome Complex; D002172:Canavanine / Q000494:pharmacology; D002467:Cell Nucleus / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D018869:Heat-Shock Response; D009097:Multienzyme Complexes / Q000378:metabolism*; D046912:Multiprotein Complexes; D009154:Mutation; D010447:Peptide Hydrolases; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D011506:Proteins / Q000235:genetics / Q000378:metabolism
D018840:HSP70 Heat-Shock Proteins; D009097:Multienzyme Complexes; D046912:Multiprotein Complexes; D010940:Plant Proteins; D011506:Proteins; D002172:Canavanine; D010447:Peptide Hydrolases; D000075686:COP9 Signalosome Complex; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex