title: Cysteine methylation disrupts ubiquitin-chain sensing in NF-κB activation.
abstract: NF-κB is crucial for innate immune defence against microbial infection. Inhibition of NF-κB signalling has been observed with various bacterial infections. The NF-κB pathway critically requires multiple ubiquitin-chain signals of different natures. The question of whether ubiquitin-chain signalling and its specificity in NF-κB activation are regulated during infection, and how this regulation takes place, has not been explored. Here we show that human TAB2 and TAB3, ubiquitin-chain sensory proteins involved in NF-κB signalling, are directly inactivated by enteropathogenic Escherichia coli NleE, a conserved bacterial type-III-secreted effector responsible for blocking host NF-κB signalling. NleE harboured an unprecedented S-adenosyl-l-methionine-dependent methyltransferase activity that specifically modified a zinc-coordinating cysteine in the Npl4 zinc finger (NZF) domains in TAB2 and TAB3. Cysteine-methylated TAB2-NZF and TAB3-NZF (truncated proteins only comprising the NZF domain) lost the zinc ion as well as the ubiquitin-chain binding activity. Ectopically expressed or type-III-secretion-system-delivered NleE methylated TAB2 and TAB3 in host cells and diminished their ubiquitin-chain binding activity. Replacement of the NZF domain of TAB3 with the NleE methylation-insensitive Npl4 NZF domain resulted in NleE-resistant NF-κB activation. Given the prevalence of zinc-finger motifs and activation of cysteine thiol by zinc binding, methylation of zinc-finger cysteine might regulate other eukaryotic pathways in addition to NF-κB signalling.
authors.affiliation: Graduate Program in Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Ding
authors.forename: Jixin
authors.initials: J
authors.lastname: Cui
authors.forename: Hao
authors.initials: H
authors.lastname: Xu
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.forename: Yi-Nan
authors.initials: YN
authors.lastname: Gong
authors.forename: Liyan
authors.initials: L
authors.lastname: Hu
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhou
authors.forename: Jianning
authors.initials: J
authors.lastname: Ge
authors.forename: Qiuhe
authors.initials: Q
authors.lastname: Lu
authors.forename: Liping
authors.initials: L
authors.lastname: Liu
authors.forename: She
authors.initials: S
authors.lastname: Chen
authors.forename: Feng
authors.initials: F
authors.lastname: Shao
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000378:metabolism*; D058947:Bacterial Secretion Systems; D003545:Cysteine / Q000378:metabolism*; D054308:Enteropathogenic Escherichia coli / Q000378:metabolism / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000378:metabolism*; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D008715:Methionine / Q000031:analogs & derivatives / Q000378:metabolism; D008745:Methylation; D008780:Methyltransferases / Q000378:metabolism; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D015398:Signal Transduction; D013379:Substrate Specificity; D048029:TNF Receptor-Associated Factor 6; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism*; D037521:Virulence Factors / Q000378:metabolism*; D016335:Zinc Fingers; D000099151:MAP Kinase Kinase Kinase 7
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D058947:Bacterial Secretion Systems; D003545:Cysteine; D029968:Escherichia coli Proteins; D047908:Intracellular Signaling Peptides and Proteins; D020930:MAP Kinase Kinase Kinases; D008715:Methionine; D008780:Methyltransferases; D016328:NF-kappa B; D048029:TNF Receptor-Associated Factor 6; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins; D025801:Ubiquitin; D037521:Virulence Factors; D000099151:MAP Kinase Kinase Kinase 7; C526043:NleE protein, E coli; C410585:TAB2 protein, human; C481053:TAB3 protein, human