Subtle variation within conserved effector operon gene products contributes to T6SS-mediated killing and immunity

• DOI: 10.1371/journal.ppat.1006729
• Publication Date: 2017-11-20T18:40:35Z
• Authors: Christopher J. Al...; Stephanie D. Himpsl; Kevin Zhu; Haley L. Hershey; Ninette Musili; Jessa E. Miller; Harry L. T. Mobley
• Keywords: 0301 basic medicine; 0303 health sciences; QH301-705.5; RC581-607; Type VI Secretion Systems; 3. Good health; 03 medical and health sciences; Bacterial Proteins; Operon; Escherichia coli; Mutagenesis, Site-Directed; Immunologic diseases. Allergy; Biology (General); Proteus mirabilis; Vibrio cholerae; Research Article; Transcription Factors

Type VI secretion systems (T6SS) function to deliver lethal payloads into target cells. Many studies have shown that protection against a single, T6SS effector protein requires cognate antidote immunity protein, both of which are often encoded together in two-gene operon. The and an effector-immunity pair is sufficient for killing immunity. HereIn this paper we describe operon differs from conventional pairs eight genes necessary function, yet can be countered by single protein. In study, investigated the role PefE plays recognition between two strains harboring nearly identical operons. Interestingly, despite containing seven proteins, less conserved proteins only provided their native effectors, suggesting specificity could dependent on variation within one gene product. variable product, PefD, upstream pefE, displays toxic activity independent T6SS-activity. while entire pef was exert via P. mirabilis, production PefD alone unable activity. Chimeric constructed mirabilis were used localize three amino acids. A promiscuous created using site-directed mutagenesis change these residues variant another. These findings support notion subtle differences effectors T6SS-mediated kin discrimination additional factors as T6SS-dependent effector.