A Comparative Structure/Function Analysis of Two Type IV Pilin DNA Receptors Defines a Novel Mode of DNA Binding

Jamie-Lee Berry,Yingqi Xu,Philip N Ward,Susan M Lea,Stephen J Matthews,Vladimir Pelicic

doi:10.1016/j.str.2016.04.001

Jamie-Lee Berry, Yingqi Xu + Show 4 more

Open Access

https://doi.org/10.1016/j.str.2016.04.001

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Abstract

SummaryDNA transformation is a widespread process allowing bacteria to capture free DNA by using filamentous nano-machines composed of type IV pilins. These proteins can act as DNA receptors as demonstrated by the finding that Neisseria meningitidis ComP minor pilin has intrinsic DNA-binding ability. ComP binds DNA better when it contains the DNA-uptake sequence (DUS) motif abundant in this species genome, playing a role in its trademark ability to selectively take up its own DNA. Here, we report high-resolution structures for meningococcal ComP and Neisseria subflava ComPsub, which recognize different DUS motifs. We show that they are structurally identical type IV pilins that pack readily into filament models and display a unique DD region delimited by two disulfide bonds. Functional analysis of ComPsub defines a new mode of DNA binding involving the DD region, adapted for exported DNA receptors.

Highlights

Numerous bacterial species, defined as naturally competent, are able to capture free DNA from the environment and import it into their cytoplasm across formidable permeability barriers (Chen and Dubnau, 2004)
The first step involves DNA uptake mediated by type IV filamentous (Tff) nano-machines composed of type IV pilins (Berry and Pelicic, 2015), either long filaments known as type IV pili (Tfp) or elusive competencepili
We discovered that the minor Tfp component ComP, which is identical in meningococci and gonococci and is crucial for their competence (Brown et al, 2010; Wolfgang et al, 1999), is the only one of four N. meningitidis type IV pilins with intrinsic DNA-binding ability (Cehovin et al, 2013)

Summary

Introduction

Numerous bacterial species, defined as naturally competent, are able to capture free DNA from the environment and import it into their cytoplasm across formidable permeability barriers (Chen and Dubnau, 2004). The first step involves DNA uptake mediated by type IV filamentous (Tff) nano-machines composed of type IV pilins (Berry and Pelicic, 2015), either long filaments known as type IV pili (Tfp) or elusive competence (pseudo)pili. It is widely accepted (Chen and Dubnau, 2004; Maier et al, 2004) that filaments bind free DNA and pull it across the outer membrane (in Gram-negative bacteria) and/or peptidoglycan (in Gram-positive species). Imported DNA is integrated in the chromosome in a RecA-dependent manner

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