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Crystallizing Membrane Proteins for Structure Determination using Lipidic Mesophases
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Crystallizing Membrane Proteins for Structure Determination using Lipidic Mesophases

Published on: November 21, 2010

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Crystal structure of the lipid flippase MurJ in a "squeezed" form distinct from its inward- and outward-facing forms

Hidetaka Kohga1, Takaharu Mori2, Yoshiki Tanaka1

  • 1Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan.

Structure (London, England : 1993)
|June 6, 2022
PubMed

Insights

The bacterial protein MurJ flips Lipid II for cell wall synthesis. New crystal structures reveal a "squeezed" form, suggesting a novel intermediate in the essential Lipid II flipping mechanism.

Area of Science:

  • Microbiology
  • Structural Biology
  • Biochemistry

Background:

  • Bacterial peptidoglycan is essential for cell structure.
  • MurJ protein is crucial for transporting Lipid II, a key building block for peptidoglycan biosynthesis.
  • Previous studies identified inward- and outward-facing structures of MurJ.

Purpose of the Study:

  • To elucidate the mechanism of Lipid II transport by the MurJ protein.
  • To investigate novel conformational states of MurJ involved in substrate translocation.

Main Methods:

  • X-ray crystallography was used to determine the structures of MurJ.
  • Molecular dynamics simulations were performed to analyze protein dynamics.

Main Results:

  • Two inward-facing structures of Arsenophonus endosymbiont MurJ were determined.
  • A novel "squeezed" inward-facing structure of Escherichia coli MurJ was resolved, lacking a substrate-binding cavity.
  • Molecular dynamics simulations supported the "squeezed" form as an intermediate conformation.

Conclusions:

  • The study reveals a previously undescribed "squeezed" conformation of MurJ.
  • This conformation likely represents an intermediate state in the Lipid II flipping mechanism.
  • The findings enhance the understanding of how MurJ facilitates peptidoglycan biosynthesis.
Keywords:
Lipid II flippaseMD simulationMurJX-ray crystallographymembrane proteintransporter

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