3eit
the 2.6 angstrom crystal structure of CHBP, the Cif Homologue from Burkholderia pseudomallei
Structural highlights
FunctionCIF_BURPS Protein-glutamine deamidase effector that inhibits the host cell cycle and other key cellular processes such as the actin network and programmed-cell death (PubMed:19225106, PubMed:19308257, PubMed:20688984). Acts by mediating the side chain deamidation of 'Gln-40' of host NEDD8, converting it to glutamate, thereby abolishing the activity of cullin-RING-based E3 ubiquitin-protein ligase complexes (CRL complexes) (PubMed:20688984, PubMed:21903097). Inactivation of CRL complexes prevents ubiquitination and subsequent degradation of the cyclin-dependent kinase inhibitors CDKN1A/p21 and CDKN1B/p27, leading to G1 and G2 cell cycle arrests in host cells (PubMed:19308257). Deamidation of 'Gln-40' of host NEDD8 also triggers macrophage-specific programmed cell death (PubMed:23175788). Also able to catalyze deamidation of 'Gln-40' of host ubiquitin in vitro; however, NEDD8 constitutes the preferred substrate in vivo (PubMed:20688984). Also regulates the host NF-kappa-B signaling via activation of MAPK/ERK cascade: activation of host MAPK/ERK cascade is independent of CRL complexes inhibition, suggesting that Cif has other host protein targets than NEDD8 (PubMed:28166272, PubMed:29848489).[1] [2] [3] [4] [5] [6] [7] Publication Abstract from PubMedPathogenic bacteria deliver effector proteins into host cells through the type III secretion apparatus to modulate the host function. We identify a family of proteins, homologous to the type III effector Cif from enteropathogenic Escherichia coli, in pathogens including Yersinia, Photorhabdus, and Burkholderia that contain functional type III secretion systems. Like Cif, this family of proteins is capable of arresting the host cell cycle at G(2)/M. Structure of one of the family members, Cif homolog in Burkholderia pseudomallei (CHBP), reveals a papain-like fold and a conserved Cys-His-Gln catalytic triad despite the lack of primary sequence identity. For CHBP and Cif, only the putative catalytic Cys is susceptible to covalent modification by E-64, a specific inhibitor of papain-like cysteine proteases. Unlike papain-like enzymes where the S2 site is the major determinant of cleavage-site specificity, CHBP has a characteristic negatively charged pocket occupying surface areas corresponding to the S1/S1' site in papain-like proteases. The negative charge is provided by a conserved aspartate, and the pocket best fits an arginine, as revealed by molecular docking analysis. Mutation analysis establishes the essential role of the catalytic triad and the negatively charged pocket in inducing cell cycle arrest in host cells. Our results demonstrate that bacterial pathogens have evolved a unique papain-like hydrolytic activity to block the normal host cell cycle progression. A bacterial type III effector family uses the papain-like hydrolytic activity to arrest the host cell cycle.,Yao Q, Cui J, Zhu Y, Wang G, Hu L, Long C, Cao R, Liu X, Huang N, Chen S, Liu L, Shao F Proc Natl Acad Sci U S A. 2009 Mar 10;106(10):3716-21. Epub 2009 Feb 18. PMID:19225106[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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