Bernsel A

Burrows LL

Carter JA

Clark CA

Daniels C

Heijne G

Hofmann K

Islam ST

Kalynych S

Kintz EN

Knirel YuA

Krogh A

Larue K

Losick R

Marczak M

Newton GJ

Nilsson J

Robbins PW

Rocchetta HL

Rost B

Simmons DAR

Tusnády GE

Uetake H

von Heijne G

ABSTRACT
          
            Lysogenic bacteriophage D3 causes seroconversion of
            Pseudomonas aeruginosa
            PAO1 from serotype O5 to O16 by inverting the linkage between O-specific antigen (OSA) repeat units from α to β. The OSA units are polymerized by Wzy to modal lengths regulated by Wzz
            1
            and Wzz
            2
            . A key component of the D3 seroconversion machinery is the
            i
            nhibitor of
            α
            -
            p
            olymerase (Iap) peptide, which is able to solely suppress α-linked long-chain OSA production in
            P. aeruginosa
            PAO1. To establish the target specificity of Iap for Wzy
            α
            , changes in OSA phenotypes were examined via Western immunoblotting for
            wzz
            1
            and
            wzz
            2
            single-knockout strains, as well as a
            wzz
            1
            wzz
            2
            double knockout, following the expression of
            iap
            from a tuneable vector. Increased induction of Iap expression completely abrogated OSA production in the
            wzz
            1
            wzz
            2
            double mutant, while background levels of OSA production were still observed in either of the single mutants. Therefore, Iap inhibition of OSA biosynthesis was most effective in the absence of both Wzz proteins. Sequence alignment analyses revealed a high degree of similarity between Iap and the first transmembrane segment (TMS) of either Wzz
            1
            or Wzz
            2
            . Various topology prediction analyses of the Iap sequence consistently predicted the presence of a single TMS, suggesting a propensity for Iap to insert itself into the inner membrane (IM). The compromised ability of Iap to abrogate Wzy
            α
            function in the presence of Wzz
            1
            or Wzz
            2
            provides compelling evidence that inhibition occurs after Wzy
            α
            inserts itself into the IM and is achieved through mimicry of the first TMS from the Wzz proteins of
            P. aeruginosa
            PAO1.
          </jats:p

Véronique L. Taylor

Molly L. Udaskin

Salim T. Islam

Joseph S. Lam

Crossref

Journal of Bacteriology

The D3 Bacteriophage α-Polymerase Inhibitor (Iap) Peptide Disrupts O-Antigen Biosynthesis through Mimicry of the Chain Length Regulator Wzz in Pseudomonas aeruginosa

The D3 Bacteriophage α-Polymerase Inhibitor (Iap) Peptide Disrupts O-Antigen Biosynthesis through Mimicry of the Chain Length Regulator Wzz in Pseudomonas aeruginosa

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