| Structural highlights
Function
[SGT1_YEAST] Involved in ubiquitination and subsequent proteasomal degradation of target proteins. Required for both entry into S phase and kinetochore function. Also involved in cyclic AMP (cAMP) pathway, possibly by participating in the assembly or the conformational activation of specific multiprotein complexes.[1] [2] [SKP1_YEAST] Essential component of the E3 ubiquitin ligase complex SCF (SKP1-CUL1-F-box protein) ubiquitin ligase complex, which mediates the ubiquitination and subsequent proteasomal degradation of target proteins like phosphorylated SIC1. Participates in the attachment of chromosomes to the spindle. Acts as a regulatory component of the centromere DNA-binding protein complex CBF3, which is essential for chromosome segregation and movement of centromeres along microtubules. CBF3 is required for the recruitment of other kinetochore complexes to CEN DNA. It plays a role in the attachment of chromosomes to the spindle and binds selectively to a highly conserved DNA sequence called CDEIII, found in centromeres and in several promoters. The association of CBF3C with CBF3D and SGT1 is required for CBF3C activation and CBF3 assembly. SKP1/CBF3D could retrieve cyclins or cyclin-CDK-like proteins into the kinetochore thus providing cell cycle-regulated kinetochore activity. Involved in the regulation of methionine biosynthesis genes. Facilitates association of CDC53 with CDC4 and of ROY1 with YPT52.[3] [4] [5] [6] [7] [8] [9]
Publication Abstract from PubMed
The essential cochaperone Sgt1 recruits Hsp90 chaperone activity to a range of cellular factors including SCF E3 ubiquitin ligases and the kinetochore in eukaryotes. In these pathways Sgt1 interacts with Skp1, a small protein that heterodimerizes with proteins containing the F-box motif. We have determined the crystal structure of the interacting domains of Saccharomyces cerevisiae Sgt1 and Skp1 at 2.8 A resolution and validated the interface in the context of the full-length proteins in solution. The BTB/POZ domain of Skp1 associates with Sgt1 via the concave surface of its TPR domain using residues that are conserved in humans. Dimerization of yeast Sgt1 occurs via an insertion that is absent from monomeric human Sgt1. We identify point mutations that disrupt dimerization and Skp1 binding in vitro and find that the interaction with Skp1 is an essential function of Sgt1 in yeast. Our data provide a structural rationale for understanding the phenotypes of temperature-sensitive Sgt1 mutants and for linking Skp1-associated proteins to Hsp90-dependent pathways.
The crystal structure of the Sgt1-Skp1 complex: the link between Hsp90 and both SCF E3 ubiquitin ligases and kinetochores.,Willhoft O, Kerr R, Patel D, Zhang W, Al-Jassar C, Daviter T, Millson SH, Thalassinos K, Vaughan CK Sci Rep. 2017 Jan 31;7:41626. doi: 10.1038/srep41626. PMID:28139700[10]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Kitagawa K, Skowyra D, Elledge SJ, Harper JW, Hieter P. SGT1 encodes an essential component of the yeast kinetochore assembly pathway and a novel subunit of the SCF ubiquitin ligase complex. Mol Cell. 1999 Jul;4(1):21-33. PMID:10445024
- ↑ Dubacq C, Guerois R, Courbeyrette R, Kitagawa K, Mann C. Sgt1p contributes to cyclic AMP pathway activity and physically interacts with the adenylyl cyclase Cyr1p/Cdc35p in budding yeast. Eukaryot Cell. 2002 Aug;1(4):568-82. PMID:12456005
- ↑ Connelly C, Hieter P. Budding yeast SKP1 encodes an evolutionarily conserved kinetochore protein required for cell cycle progression. Cell. 1996 Jul 26;86(2):275-85. PMID:8706132
- ↑ Bai C, Sen P, Hofmann K, Ma L, Goebl M, Harper JW, Elledge SJ. SKP1 connects cell cycle regulators to the ubiquitin proteolysis machinery through a novel motif, the F-box. Cell. 1996 Jul 26;86(2):263-74. PMID:8706131
- ↑ Skowyra D, Craig KL, Tyers M, Elledge SJ, Harper JW. F-box proteins are receptors that recruit phosphorylated substrates to the SCF ubiquitin-ligase complex. Cell. 1997 Oct 17;91(2):209-19. PMID:9346238
- ↑ Feldman RM, Correll CC, Kaplan KB, Deshaies RJ. A complex of Cdc4p, Skp1p, and Cdc53p/cullin catalyzes ubiquitination of the phosphorylated CDK inhibitor Sic1p. Cell. 1997 Oct 17;91(2):221-30. PMID:9346239
- ↑ Liu Y, Nakatsukasa K, Kotera M, Kanada A, Nishimura T, Kishi T, Mimura S, Kamura T. Non-SCF-type F-box protein Roy1/Ymr258c interacts with a Rab5-like GTPase Ypt52 and inhibits Ypt52 function. Mol Biol Cell. 2011 May;22(9):1575-84. doi: 10.1091/mbc.E10-08-0716. Epub 2011, Mar 9. PMID:21389113 doi:10.1091/mbc.E10-08-0716
- ↑ Patton EE, Willems AR, Sa D, Kuras L, Thomas D, Craig KL, Tyers M. Cdc53 is a scaffold protein for multiple Cdc34/Skp1/F-box proteincomplexes that regulate cell division and methionine biosynthesis in yeast. Genes Dev. 1998 Mar 1;12(5):692-705. PMID:9499404
- ↑ Escusa S, Laporte D, Massoni A, Boucherie H, Dautant A, Daignan-Fornier B. Skp1-Cullin-F-box-dependent degradation of Aah1p requires its interaction with the F-box protein Saf1p. J Biol Chem. 2007 Jul 13;282(28):20097-103. Epub 2007 May 21. PMID:17517885 doi:10.1074/jbc.M702425200
- ↑ Willhoft O, Kerr R, Patel D, Zhang W, Al-Jassar C, Daviter T, Millson SH, Thalassinos K, Vaughan CK. The crystal structure of the Sgt1-Skp1 complex: the link between Hsp90 and both SCF E3 ubiquitin ligases and kinetochores. Sci Rep. 2017 Jan 31;7:41626. doi: 10.1038/srep41626. PMID:28139700 doi:http://dx.doi.org/10.1038/srep41626
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