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Updated: Jul 1, 2026
An Integrated Approach for Microprotein Identification and Sequence Analysis
Published on: July 12, 2022
Genetic analysis of MraY inhibition by the phiX174 protein E
Yi Zheng1, Douglas K Struck, Thomas G Bernhardt
1Department of Biochemistry and Biophysics, Texas A & M University, College Station, Texas 77843-2128, USA.
Abstract:
Protein E, the lysis protein of bacteriophage phiX174, is a specific inhibitor of MraY, the phospho-MurNAc-pentapeptide translocase that catalyzes the synthesis of lipid I in the conserved pathway for peptidoglycan biosynthesis. The original evidence for this inhibition was the isolation of two spontaneous E-resistance mraY mutants. Here we report further genetic studies aimed at dissecting the interaction between E and MraY, using a genetic strategy that is facile, rapid, and does not depend on the availability of purified E, purified MraY, or its substrates. This system relies on the ability of mraY or its enzymatically inactive D267N allele to protect cells from lysis after induction of a chimeric lambda :: E prophage. Using this approach, the MraY protein from Bacillus subtilis, which shares 43% sequence identity with the Escherichia coli enzyme, was found to interact weakly, if at all, with E. A potential E binding site defined by transmembrane domains 5 and 9 has been identified by isolating more mraY mutants resistant to E inhibition. Genetic analysis indicates that these E-resistant alleles fall into three classes on the basis of the affinity of the encoded proteins for MraY.
Insights
Bacteriophage phiX174 Protein E inhibits MraY, crucial for bacterial cell wall synthesis. Genetic studies identified potential binding sites on MraY, revealing insights into this essential protein-protein interaction.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Protein E of bacteriophage phiX174 specifically inhibits MraY, a key enzyme in peptidoglycan biosynthesis.
- MraY catalyzes the synthesis of lipid I, an essential step in bacterial cell wall formation.
- Previous studies identified E-resistant mraY mutants, suggesting a direct interaction.
Purpose of the Study:
- To genetically dissect the interaction between Protein E and MraY.
- To identify potential binding sites and characterize the nature of their interaction.
- To investigate the cross-species interaction between Protein E and MraY from different bacteria.
Main Methods:
- Utilized a genetic system employing a chimeric lambda :: E prophage and mraY alleles (wild-type and D267N mutant).
- Assessed cell lysis protection conferred by mraY expression upon E induction.
- Isolated and analyzed new E-resistant mraY mutants to map interaction sites.
Main Results:
- The MraY protein from Bacillus subtilis showed weak or no interaction with Protein E.
- A potential Protein E binding site was mapped to transmembrane domains 5 and 9 of MraY.
- E-resistant mraY alleles were classified into three groups based on their affinity for Protein E.
Conclusions:
- The study provides a facile genetic approach to investigate E-MraY interactions without requiring purified components.
- Transmembrane domains 5 and 9 are implicated in the binding of Protein E to MraY.
- Genetic analysis reveals varying affinities in the E-MraY interaction, offering insights into specificity.
