Dataset Information

Mapping the interactions between Escherichia coli TolQ transmembrane segments.

ABSTRACT: The tolQRAB-pal operon is conserved in Gram-negative genomes. The TolQRA proteins of Escherichia coli form an inner membrane complex in which TolQR uses the proton-motive force to regulate TolA conformation and the in vivo interaction of TolA C-terminal region with the outer membrane Pal lipoprotein. The stoichiometry of the TolQ, TolR, and TolA has been estimated and suggests that 4-6 TolQ molecules are associated in the complex, thus involving interactions between the transmembrane helices (TMHs) of TolQ, TolR, and TolA. It has been proposed that an ion channel forms at the interface between two TolQ and one TolR TMHs involving the TolR-Asp(23), TolQ-Thr(145), and TolQ-Thr(178) residues. To define the organization of the three TMHs of TolQ, we constructed epitope-tagged versions of TolQ. Immunodetection of in vivo and in vitro chemically cross-linked TolQ proteins showed that TolQ exists as multimers in the complex. To understand how TolQ multimerizes, we initiated a cysteine-scanning study. Results of single and tandem cysteine substitution suggest a dynamic model of helix interactions in which the hairpin formed by the two last TMHs of TolQ change conformation, whereas the first TMH of TolQ forms intramolecular interactions.

SUBMITTER: Zhang XY

PROVIDER: S-EPMC3064227 | biostudies-literature | 2011 Apr

REPOSITORIES: biostudies-literature

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Mapping the interactions between Escherichia coli TolQ transmembrane segments.

Zhang Xiang Y-Z XY Goemaere Emilie L EL Seddiki Nadir N Célia Hervé H Gavioli Marthe M Cascales Eric E Lloubes Roland R

The Journal of biological chemistry 20110201 13

The tolQRAB-pal operon is conserved in Gram-negative genomes. The TolQRA proteins of Escherichia coli form an inner membrane complex in which TolQR uses the proton-motive force to regulate TolA conformation and the in vivo interaction of TolA C-terminal region with the outer membrane Pal lipoprotein. The stoichiometry of the TolQ, TolR, and TolA has been estimated and suggests that 4-6 TolQ molecules are associated in the complex, thus involving interactions between the transmembrane helices (TM ...[more]

PMID: 21285349

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Project description:Bacteriophages are the most abundant and diverse biological entities on Earth. Phages exhibit strict host specificity that is largely conferred by adsorption. However, the mechanism underlying this phage host specificity remains poorly understood. In this study, we examined the interaction between outer membrane protein C (OmpC), one of the Escherichia coli receptors, and the long tail fibers of bacteriophage T4. T4 phage uses OmpC of the K-12 strain, but not of the O157 strain, for adsorption, even though OmpCs from the two E. coli strains share 94% homology. We identified amino acids P177 and F182 in loop 4 of the K-12 OmpC as essential for T4 phage adsorption in the copresence of loops 1 and 5. Analyses of phage mutants capable of adsorbing to OmpC mutants demonstrated that amino acids at positions 937 and 942 of the gp37 protein, which is present in the distal tip (DT) region of the T4 long tail fibers, play an important role in adsorption. Furthermore, we created a T4 phage mutant library with artificial modifications in the DT region and isolated and characterized multiple phage mutants capable of adsorbing to OmpC of the O157 strain or lipopolysaccharide of the K-12 strain. These results shed light on the mechanism underlying the phage host specificity mediated by gp37 and OmpC and may be useful in the development of phage therapy via artificial modifications of the DT region of T4 phage. IMPORTANCE Understanding the host specificity of phages will lead to the development of phage therapy. The interaction between outer membrane protein C (OmpC), one of the Escherichia coli receptors, and the gp37 protein present in the distal tip (DT) region of the long tail fibers of T4 bacteriophages largely determines their host specificity. Here, we elucidated the amino acid residues important for the interaction between gp37 and OmpC. This result suggests that the shapes of both proteins at the binding interface play important roles in their interactions, which are likely mediated by multiple residues of both binding partners. Additionally, we successfully isolated multiple phage mutants capable of adsorbing to a variety of E. coli receptors using a mutant T4 phage library with artificial modifications in the DT region, providing a foundation for the alteration of the host specificity.

Dataset Information

Mapping the interactions between Escherichia coli TolQ transmembrane segments.

Publications

Mapping the interactions between Escherichia coli TolQ transmembrane segments.

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