A broadly conserved gram-positive lipoprotein regulates cell elongation

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Bacterial cell walls, composed of peptidoglycan (PG), are crucial for structural integrity and protection against osmotic lysis.
• The Rod complex (elongasome) is a key multi-protein machinery responsible for bacterial cell wall synthesis and elongation.
• Identifying novel components of the Rod complex is essential for understanding bacterial growth and developing new antimicrobial strategies.

Purpose of the Study:

• To identify previously undiscovered components of the bacterial Rod complex.
• To investigate the function and interactions of the identified lipoprotein, ClcR, within the cell wall synthesis pathway.

Main Methods:

• High-throughput genetics and AlphaFold-Multimer computational screening were employed to identify novel protein interactions.
• Transposon sequencing (Tn-seq) datasets were analyzed using a newly developed webtool.
• Co-immunoprecipitation and functional assays were used to validate protein interactions and assess ClcR's role in cell wall synthesis.

Main Results:

• The lipoprotein ClcR was identified as a novel component of the Rod complex, conserved in Gram-positive bacteria.
• ClcR interacts with Rod complex transpeptidases and positively regulates their activity, functioning independently of known regulators like MreCD.
• ClcR is essential for proper cell elongation and shape in *Bacillus anthracis* and contributes to cell wall synthesis in *Bacillus subtilis* and *Staphylococcus aureus*.

Conclusions:

• ClcR is a broadly conserved and essential component of the bacterial cell wall elongation machinery.
• The study provides a framework for discovering protein-protein interactions using integrated genetic and computational approaches.
• The developed webtool facilitates the analysis of Tn-seq data, aiding future research in bacterial genetics.