Tyrosine-Phosphorylated Caveolin-1 Blocks Bacterial Uptake by Inducing Vav2-RhoA-Mediated Cytoskeletal Rearrangements

Jan Peter Boettcher,Yuri Churin,Hans Thorn,Malvika Pompaiah,Gavin Macbeath,Volker Brinkmann,Marieluise Kirchner,Thomas F Meyer,Alexis Kaushansky,Gary E Ward

doi:10.1371/journal.pbio.1000457

Abstract

Author SummaryLike many bacterial pathogens, successful attachment of Neisseria gonorrhoeae—the causative agent of the sexually transmitted disease gonorrhoea—to its host cells depends on specialized structures on the bacterial surface called type IV pili (Tfp). Pathogen attachment induces changes within host cells that may facilitate and promote infection. In this study, we identify some of the earliest cellular signals elicited by N. gonorrhoeae during infection, which, in this case, prevent the organism from entering the cell precociously. After attachment to host cells the bacteria form microcolonies on the cell surface. Underneath these microcolonies, so-called cortical plaques form within the host cell—these contain the cytoskeleton protein actin and a range of signaling proteins. We show that N. gonorrhoeae recruits a host cell protein called caveolin-1 to the cell membrane where the bacteria are attached; here, caveloin-1 effectively impedes uptake of the bacteria by activating a signaling cascade that involves its phosphorylation on a tyrosine residue and subsequent interactions with proteins that regulate the cytoskeleton. Thus, these proteins play a pivotal role in maintaining N. gonorrhoeae in the extracellular milieu. By extrapolating our findings to another Tfp-producing bacterium, the enteropathogenic Escherichia coli, we argue that the establishment and maintenance of this extracellular state benefits certain pathogens by giving them time to express proteins required for subsequent steps of infection.

Highlights

The primarily extracellular obligate human pathogen Neisseria gonorrhoeae (P+GC) is the causative agent of the sexually transmitted disease gonorrhoea, affecting over 60 million people every year worldwide [1]
Tfp are proteinaceous filaments that play a crucial role in pathogenesis by mediating the initial attachment to host cell receptors and are expressed on the surface of a variety of bacterial pathogens such as Gram-negative N. meningitidis, Pseudomonas aeruginosa, and enteropathogenic E. coli (EPEC) as well as Gram-positive Streptococcus sanguis and Clostridium perfringens [3]
Tfp-expression and cytoskeletal remodeling allows N. meningitidis to resist shear stress possibly encountered in the bloodstream [5], and mechanical forces generated by pilus retraction of piliated Neisseria gonorrhoeae (P+GC) lead to cytoprotection [6]

Summary

Introduction

The primarily extracellular obligate human pathogen Neisseria gonorrhoeae (P+GC) is the causative agent of the sexually transmitted disease gonorrhoea, affecting over 60 million people every year worldwide [1]. It is a type IV pili (Tfp)-producing bacteria that colonizes mucosal epithelia of the human urogenital tract [2]. The early stages of infection with P+GC are characterized by Tfp-mediated attachment to host cells [7] This is followed by retraction of pili in a force-generating depolymerization process [8] and formation of microcolonies on the surface of host epithelial cells [2].

Author Summary

Findings

Methods