Cysteine methyltransferase effector that inhibits host cell NF-kappa-B activation by preventing nuclear translocation of host protein RELA/p65 (PubMed:20485572). Acts by mediating cysteine methylation of host proteins TAB2 and TAB3: methylation of a conserved cysteine residue of the RanBP2-type zinc finger (NZF) of TAB2 and TAB3 disrupts zinc-binding, thereby inactivating the ubiquitin chain-binding activity of TAB2 and TAB3, leading to NF-kappa-B inactivation. Also mediates cysteine methylation of host protein ZRANB3, inactivating its ability to bind ubiquitin chains (By similarity). L-cysteinyl-[protein] + S-adenosyl-L-methionine = H(+) + S-adenosyl-L-homocysteine + S-methyl-L-cysteinyl-[protein] Monomer. Secreted via the type III secretion system (TTSS). Mainly localizes in the cytoplasm of the infected cells, and occasionaly in the host nucleus. Belongs to the NleE/OspZ family.