Insights into the function of YciM, a heat-shock membrane protein required to maintain envelope integrity in Escherichia coli
Nicolaes, Valérie El Hajjaji, Hayat Davis, Rebecca M Van der Henst, Charles Depuydt, Matthieu Leverrier, Pauline Aertsen, Abram Haufroid, Vincent Ollagnier, Sandrine De Bolle, Xavier Ruiz, Natividad Collet, Jean-Francois # ×
American Society for Microbiology (ASM)
Journal of Bacteriology vol:196 issue:2 pages:300-309
The cell envelope of Gram-negative bacteria is an essential organelle that is important for cell shape and protection from toxic compounds. Proteins involved in envelope biogenesis are therefore attractive targets for the design of new antibacterial agents. In a search for new envelope assembly factors, we screened a collection of Escherichia coli deletion mutants for sensitivity to detergents and hydrophobic antibiotics, a phenotype indicative of defects in the cell envelope. Strains lacking yciM were among the most sensitive strains of the mutant collection. Further characterization of yciM mutants revealed that they display a thermosensitive growth defect on low-osmolarity medium and that they have a significantly altered cell morphology. At elevated temperatures, yciM mutants form bulges containing cytoplasmic material and subsequently lyse. We also discovered that yciM genetically interacts with envC, a gene encoding a regulator of the activity of peptidoglycan amidases. Altogether these results indicate that YciM is required for envelope integrity. Biochemical characterization of the protein showed that YciM is anchored to the inner membrane via its N-terminus, the rest of the protein being exposed to the cytoplasm. Two CXXC motifs are present at the C-terminus of YciM and serve to coordinate a redox-sensitive iron center of the rubredoxin-type. Both the N-terminal membrane anchor and the C-terminal iron center of YciM are important for function.