3aji
From Proteopedia
Structure of Gankyrin-S6ATPase photo-cross-linked site-specifically, and incoporated by genetic code expansion
Structural highlights
Function[PSD10_MOUSE] Acts as a chaperone during the assembly of the 26S proteasome, specifically of the PA700/19S regulatory complex (RC). In the initial step of the base subcomplex assembly is part of an intermediate PSMD10:PSMC4:PSMC5:PAAF1 module which probably assembles with a PSMD5:PSMC2:PSMC1:PSMD2 module (By similarity). Independently of the proteasome, regulates EGF-induced AKT activation through inhibition of the RHOA/ROCK/PTEN pahway, leading to prolonged AKT activation. Plays an important role in RAS-induced tumorigenesis. Acts as an oncoprotein by being involved in negative regulation of tumor suppressors RB1 and p53/TP53. Overexpression is leading to phosphorylation of RB1 and proteasomal degradation of RB1. Regulates CDK4-mediated phosphorylation of RB1 by competing with CDKN2A for binding with CDK4. Facilitates binding of MDM2 to p53/TP53 and the mono- and polyubiquitination of p53/TP53 by MDM2 suggesting a function in targeting the TP53:MDM2 complex to the 26S proteasome. Involved in p53-independent apoptosis. Involved in regulation of NF-kappa-B by retaining it in the cytoplasm. Binds to the NF-kappa-B component RELA and accelerates its XPO1/CRM1-mediated nuclear export (By similarity). [PRS6B_MOUSE] The 26S protease is involved in the ATP-dependent degradation of ubiquitinated proteins. The regulatory (or ATPase) complex confers ATP dependency and substrate specificity to the 26S complex. Publication Abstract from PubMedThe benzophenone photophore is widely used to photo-cross-link macromolecules. Recent developments in genetic code expansion have allowed the biosynthesis of proteins with p-benzoyl-l-phenylalanine (pBpa) at defined sites, for covalent bonding with interacting proteins. However, the structure of a photo-cross-linked protein complex had not been revealed, and thus neither the actual structure of the "photobridge" in a complex nor the influence of this covalent bridge on the overall complex structure was known. In this study, we determine the crystal structure of the cross-linked complex of the liver oncoprotein gankyrin and the C-terminal domain of S6 proteasomal protein (S6C), at 2.05 A resolution. First, the photoreactive amino acid was separately incorporated into gankyrin at 16 sites on the protein surface, and two variants that efficiently formed a covalent bond with S6C were found. The yield of one of the cross-linked products, with pBpa in place of Arg85 in gankyrin, was maximized for crystallization via optimization of the duration of complex exposure to 365 nm light. The structure revealed that the carbonyl group of the benzophenone of pBpa85 formed a covalent bond exclusively with the Cgamma atom of Glu356 in S6C, showing the high selectivity of formation of cross-links by pBpa. In addition, the cross-linked structure exhibited little structural distortion from the native complex structure. Our results demonstrated that cross-linking with site-specifically incorporated pBpa preserves the native binding mode and is useful for probing protein-protein interactions. Crystallographic Study of a Site-Specifically Cross-Linked Protein Complex with a Genetically Incorporated Photoreactive Amino Acid .,Sato S, Mimasu S, Sato A, Hino N, Sakamoto K, Umehara T, Yokoyama S Biochemistry. 2010 Dec 16. PMID:21128684[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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