Báo cáo khoa học: The sensor protein KdpD inserts into the Escherichia coli membrane independent of the Sec translocase and YidC

The Sensor Protein KdpD Inserts into the Escherichia Coli Membrane Independent of the Sec Translocase and YidC

Authors: Sandra J. Facey and Andreas Kuhn

Field: Microbiology and Molecular Biology

Document Content: This study investigates the mechanism by which the sensor protein KdpD, a crucial component of the osmoregulation system in Escherichia coli, inserts into the bacterial inner membrane. KdpD is characterized by four transmembrane regions and short periplasmic loops. The research reveals that KdpD, particularly its initial periplasmic loop, can insert into the membrane independently of the established Sec translocase and YidC pathways. However, extending these loops with epitope tags alters their translocation requirements, with the second loop then depending on SecE and YidC, and the first loop showing a dependence on the proton motive force. The study also explores the insertion of fragmented KdpD proteins, suggesting that transmembrane helices are inserted in pairs. These findings contribute to understanding the diverse mechanisms of membrane protein insertion, particularly for proteins with short periplasmic regions, and propose a novel, unassisted insertion pathway for certain membrane proteins.

Detailed Table of Contents:

• Introduction
• Materials and Methods
• Results
• Membrane insertion of the KdpD protein
• Short epitopes introduced into the periplasmic regions allow the analysis of insertion events
• Membrane insertion of split osmosensor fragments
• Discussion
• Acknowledgements
• References