Cellular Electron Microscopy Imaging Reveals the Localization of the Hfq Protein Close to the Bacterial Membrane

Elia Diestra,Véronique Arluison,Cristina Risco,Bastien Cayrol,Claudine Mayer

doi:10.1371/journal.pone.0008301

Abstract

BackgroundHfq is a bacterial protein involved in several aspects of nucleic acid transactions, but one of its best-characterized functions is to affect the post-transcriptional regulation of mRNA by virtue of its interactions with stress-related small regulatory (sRNA).Methodology and Principal FindingBy using cellular imaging based on the metallothionein clonable tag for electron microscopy, we demonstrate here that in addition to its localization in the cytoplasm and in the nucleoid, a significant amount of Hfq protein is located at the cell periphery. Simultaneous immunogold detection of specific markers strongly suggests that peripheral Hfq is close to the bacterial membrane. Because sRNAs regulate the synthesis of several membrane proteins, our result implies that the sRNA- and Hfq-dependent translational regulation of these proteins takes place in the cytoplasmic region underlying the membrane.ConclusionsThis finding supports the proposal that RNA processing and translational machineries dedicated to membrane protein translation may often be located in close proximity to the membrane of the bacterial cell.

Highlights

Hfq is an abundant and phylogenetically conserved bacterial protein involved in several aspects of nucleic acid transactions
This finding supports the proposal that RNA processing and translational machineries dedicated to membrane protein translation may often be located in close proximity to the membrane of the bacterial cell
One of its best-characterized functions is to affect the posttranscriptional regulation of mRNA translation by virtue of its interactions with small regulatory noncoding RNAs

Summary

Introduction

Hfq is an abundant and phylogenetically conserved bacterial protein involved in several aspects of nucleic acid transactions. One of its best-characterized functions is to affect the posttranscriptional regulation of mRNA translation by virtue of its interactions with small regulatory noncoding RNAs (sRNAs) The identification of these sRNAs in bacteria has recently increased dramatically and a number of studies showed that they contribute to the responses to stress conditions such as oxidative-, envelopeor osmotic stress [reviewed in [1,2]]. Most of these sRNAs act by base pairing with their target mRNA but are usually not encoded in the same genetic region. Hfq is a bacterial protein involved in several aspects of nucleic acid transactions, but one of its bestcharacterized functions is to affect the post-transcriptional regulation of mRNA by virtue of its interactions with stressrelated small regulatory (sRNA)

Methods

Results

Conclusion