Structure and mutagenic analysis of the lipid II flippase MurJ from Escherichia coli.


The peptidoglycan cell wall provides an essential protective barrier in almost all bacteria, defining cellular morphology and conferring resistance to osmotic stress and other environmental hazards. The precursor to peptidoglycan, lipid II, is assembled on the inner leaflet of the plasma membrane. However, peptidoglycan polymerization occurs on the outer face of the plasma membrane, and lipid II must be flipped across the membrane by the MurJ protein before its use in peptidoglycan synthesis. Due to its central role in cell wall assembly, MurJ is of fundamental importance in microbial cell biology and is a prime target for novel antibiotic development. However, relatively little is known regarding the mechanisms of MurJ function, and structural data for MurJ are available only from the extremophile Thermosipho africanus Here, we report the crystal structure of substrate-free MurJ from the gram-negative model organism Escherichia coli, revealing an inward-open conformation. Taking advantage of the genetic tractability of E. coli, we performed high-throughput mutagenesis and next-generation sequencing to assess mutational tolerance at every amino acid in the protein, providing a detailed functional and structural map for the enzyme and identifying sites for inhibitor development. Lastly, through the use of sequence coevolution analysis, we identify functionally important interactions in the outward-open state of the protein, supporting a rocker-switch model for lipid II transport.

Submission Details

ID: nFC8n82P4

Submitter: Shu-Ching Ou

Submission Date: March 4, 2019, 1:20 p.m.

Version: 1

Publication Details
Zheng S;Sham LT;Rubino FA;Brock KP;Robins WP;Mekalanos JJ;Marks DS;Bernhardt TG;Kruse AC,Proc Natl Acad Sci U S A (2018) Structure and mutagenic analysis of the lipid II flippase MurJ from Escherichia coli. PMID:29891673
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Lipid II flippase MurJ P0AF17 MURJ_ECO57
100.0 Lipid II flippase MurJ P0AF16 MURJ_ECOLI
94.3 Lipid II flippase MurJ P37169 MURJ_SALTY