Active, Escherichia coli O157:H7, Recombinant NleL

Background: NleL is a type III secretion system effector protein produced by pathogenic Escherichia coli strains. It functions as an E3 ubiquitin ligase, modulating host cell signaling pathways by ubiquitinating host proteins, thereby promoting infection. NleL comprises an N-terminal β-helix formed by pentapeptide repeats (residues 1–250) and a C-terminal bilobed bacterial HECT (bHECT) catalytic domain. key motifs include the catalytic Cys387 and an E2-binding patch. NleL positions itself downstream of host E2 enzymes, directly catalyzing ubiquitin transfer to host substrates or building unanchored K6- and K48-linked polyubiquitin chains.