Combinatorial diversity of fission yeast SCF ubiquitin ligases by homo- and heterooligomeric assemblies of the F-box proteins Pop1p and Pop2p.
BMC Biochem
; 3: 22, 2002 Aug 07.
Article
en En
| MEDLINE
| ID: mdl-12167173
ABSTRACT
BACKGROUND:
SCF ubiquitin ligases share the core subunits cullin 1, SKP1, and HRT1/RBX1/ROC1, which associate with different F-box proteins. F-box proteins bind substrates following their phosphorylation upon stimulation of various signaling pathways. Ubiquitin-mediated destruction of the fission yeast cyclin-dependent kinase inhibitor Rum1p depends on two heterooligomerizing F-box proteins, Pop1p and Pop2p. Both proteins interact with the cullin Pcu1p when overexpressed, but it is unknown whether this reflects their co-assembly into bona fide SCF complexes.RESULTS:
We have identified Psh1p and Pip1p, the fission yeast homologues of human SKP1 and HRT1/RBX1/ROC1, and show that both associate with Pop1p, Pop2p, and Pcu1p into a ~500 kDa SCFPop1p-Pop2p complex, which supports polyubiquitylation of Rum1p. Only the F-box of Pop1p is required for SCFPop1p-Pop2p function, while Pop2p seems to be attracted into the complex through binding to Pop1p. Since all SCFPop1p-Pop2p subunits, except for Pop1p, which is exclusively nuclear, localize to both the nucleus and the cytoplasm, the F-box of Pop2p may be critical for the assembly of cytoplasmic SCFPop2p complexes. In support of this notion, we demonstrate individual SCFPop1p and SCFPop2p complexes bearing ubiquitin ligase activity.CONCLUSION:
Our data suggest that distinct homo- and heterooligomeric assemblies of Pop1p and Pop2p generate combinatorial diversity of SCFPop function in fission yeast. Whereas a heterooligomeric SCFPop1p-Pop2p complex mediates polyubiquitylation of Rum1p, homooligomeric SCFPop1p and SCFPop2p complexes may target unknown nuclear and cytoplasmic substrates.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Péptido Sintasas
/
Schizosaccharomyces
/
Proteínas de Schizosaccharomyces pombe
Idioma:
En
Revista:
BMC Biochem
Asunto de la revista:
BIOQUIMICA
Año:
2002
Tipo del documento:
Article
País de afiliación:
Estados Unidos