Bioinformatics identification of MurJ (MviN) as the peptidoglycan lipid II flippase in Escherichia coli - PubMed (original) (raw)

Bioinformatics identification of MurJ (MviN) as the peptidoglycan lipid II flippase in Escherichia coli

Natividad Ruiz. Proc Natl Acad Sci U S A. 2008.

Abstract

Peptidoglycan is a cell-wall glycopeptide polymer that protects bacteria from osmotic lysis. Whereas in gram-positive bacteria it also serves as scaffold for many virulence factors, in gram-negative bacteria, peptidoglycan is an anchor for the outer membrane. For years, we have known the enzymes required for the biosynthesis of peptidoglycan; what was missing was the flippase that translocates the lipid-anchored precursors across the cytoplasmic membrane before their polymerization into mature peptidoglycan. Using a reductionist bioinformatics approach, I have identified the essential inner-membrane protein MviN (renamed MurJ) as a likely candidate for the peptidoglycan flippase in Escherichia coli. Here, I present genetic and biochemical data that confirm the requirement of MurJ for peptidoglycan biosynthesis and that are in agreement with a role of MurJ as a flippase. Because of its essential nature, MurJ could serve as a target in the continuing search for antimicrobial compounds.

PubMed Disclaimer

Conflict of interest statement

The author declares no conflict of interest.

Figures

Fig. 1.

Fig. 1.

Biogenesis of peptidoglycan in E. coli. After being synthesized by MurABCDEF in the cytoplasm, UDP-MurNAc-pentapeptide is transferred to undecaprenyl phosphate by MraY, generating lipid I. Next, MurG synthesizes lipid II by adding GlcNAc (from UDP-GlcNAc) to lipid I. Lipid II is translocated across the IM by an unknown flippase. At the periplasmic side of the IM, glycosyltransferases (PGTs) assemble and elongate glycan chains, and transpeptidases (TPs) cross-link their peptide chains (dashed lines). DD-carboxypeptidases (CPs) remove terminal D-Ala from the stem pentapeptide in mature peptidoglycan.

Fig. 2.

Fig. 2.

MurJ is essential. (A) Chromosomal organization of the MurJ-depletion strain. The PBAD promoter, araC and bla were inserted 14 bp upstream of the murJ start codon so that murJ expression is under the control of PBAD and decoupled from its native PmurJ promoter. (B) Growth (measured by OD600) of depletion strain NR1154 (MC4100 ara+ Δ_lysA_::kan murJ Ω(−14::bla araC PBAD) depends on the presence of arabinose in the medium. Addition of

d

-fucose, a nonmetabolizable analog of

l

-arabinose, causes cell lysis of NR1154 but not the MurJ+ parent strain NR1157 (MC4100 ara+ Δ_lysA_::kan). (C–H) Cell morphology (under magnification ×100 phase objective) of wild-type (NR1157, C) and MurJ-depletion (NR1154, D–H) strains grown in the presence of fucose. During MurJ depletion, whereas some cells appear wild type (black arrows), many are larger, irregularly shaped, and form large blebs (white arrows).

Similar articles

Cited by

References

    1. Bouhss A, Trunkfield AE, Bugg TD, Mengin-Lecreulx D. The biosynthesis of peptidoglycan lipid-linked intermediates. FEMS Microbiol Rev. 2008;32:208–233. - PubMed
    1. van Heijenoort J. Lipid intermediates in the biosynthesis of bacterial peptidoglycan. Microbiol Mol Biol Rev. 2007;71:620–635. - PMC - PubMed
    1. Vollmer W, Blanot D, de Pedro MA. Peptidoglycan structure and architecture. FEMS Microbiol Rev. 2008;32:149–167. - PubMed
    1. Dramsi S, Magnet S, Davison S, Arthur M. Covalent attachment of proteins to peptidoglycan. FEMS Microbiol Rev. 2008;32:307–320. - PubMed
    1. Koch AL. Bacterial wall as target for attack: Past, present, and future research. Clin Microbiol Rev. 2003;16:673–687. - PMC - PubMed

Publication types

MeSH terms

Substances

LinkOut - more resources