title: Inhibition of cullin RING ligases by cycle inhibiting factor: evidence for interference with Nedd8-induced conformational control.
abstract: Cycle inhibiting factor (Cif) is produced by pathogenic intracellular bacteria and injected into the host cells via a type III secretion system. Cif is known to interfere with the eukaryotic cell cycle by inhibiting the function of cullin RING E3 ubiquitin ligases (CRLs). Cullin proteins form the scaffold protein of CRLs and are modified with the ubiquitin-like protein Nedd8, which exerts important conformational control required for CRL activity. Cif has recently been shown to catalyze the deamidation of Gln40 in Nedd8 to Glu. Here, we addressed how Nedd8 deamidation inhibits CRL activity. Our results indicate that Burkholderia pseudomallei Cif (also known as CHBP) inhibits the deconjugation of Nedd8 in vivo by inhibiting binding of the deneddylating COP9 signalosome (CSN) complex. We provide evidence that the reduced binding of CSN and the inhibition of CRL activity by Cif are due to interference with Nedd8-induced conformational control, which is dependent on the interaction between the Nedd8 hydrophobic patch and the cullin winged-helix B subdomain. Of note, mutation of Gln40 to Glu in ubiquitin, an additional target of Cif, inhibits the interaction between the hydrophobic surface of ubiquitin and the ubiquitin-binding protein p62/SQSTM1, showing conceptually that Cif activity can impair ubiquitin/ubiquitin-like protein non-covalent interactions. Our results also suggest that Cif may exert additional cellular effects by interfering with the association between ubiquitin and ubiquitin-binding proteins.
authors: Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597.
authors: Boon Kim
authors: BK
authors: Boh
authors: Mei Ying
authors: MY
authors: Ng
authors: Yee Chin
authors: YC
authors: Leck
authors: Barry
authors: B
authors: Shaw
authors: Jed
authors: J
authors: Long
authors: Guang Wen
authors: GW
authors: Sun
authors: Yunn Hwen
authors: YH
authors: Gan
authors: Mark S
authors: MS
authors: Searle
authors: Robert
authors: R
authors: Layfield
authors: Thilo
authors: T
authors: Hagen
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000494:pharmacology*; D016957:Burkholderia pseudomallei / Q000378:metabolism; D000075686:COP9 Signalosome Complex; D044842:Cullin Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008956:Models, Chemical; D046912:Multiprotein Complexes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D000075687:NEDD8 Protein; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D000071456:Sequestosome-1 Protein; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014452:Ubiquitins / Q000235:genetics / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D001426:Bacterial Proteins; D044842:Cullin Proteins; D046912:Multiprotein Complexes; D000075687:NEDD8 Protein; C082860:NEDD8 protein, human; C099718:SQSTM1 protein, human; D000071456:Sequestosome-1 Protein; D025801:Ubiquitin; D014452:Ubiquitins; D044767:Ubiquitin-Protein Ligases; D010447:Peptide Hydrolases; D000075686:COP9 Signalosome Complex