The small non-coding RNA B11 regulates multiple facets of Mycobacterium abscessus virulence

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Mycobacterium abscessus is a significant pathogen, particularly in cystic fibrosis patients.
• The roles of small regulatory RNAs (sRNAs) in M. abscessus gene regulation remain largely unexplored.

Purpose of the Study:

• To investigate the function of the sRNA B11 in M. abscessus gene regulation and virulence.
• To determine the impact of B11 on pathogen phenotypes and antibiotic resistance.

Main Methods:

• Deletion mutagenesis of the B11 sRNA in M. abscessus.
• Analysis of gene expression using RNA sequencing (RNAseq) and proteomics.
• Assessment of virulence and antibiotic resistance in mutant strains and clinical isolates.

Main Results:

• B11 deletion resulted in a rough colony morphology, increased pro-inflammatory signaling, enhanced virulence in infection models, and greater antibiotic resistance.
• Over 200 genes were differentially expressed in the B11 deletion mutant.
• Clinical isolates with B11 mutations showed similar expression trends, indicating partial loss of function.
• B11 directly represses translation by binding to ribosome binding sites (RBS) of target genes, including components of the ESX-4 secretion system.

Conclusions:

• B11 functions as a direct negative regulator and potentially an indirect positive regulator of gene expression in M. abscessus.
• B11 influences pleiotropic effects on gene expression and clinically relevant phenotypes.
• Hypomorphic B11 mutations in clinical strains suggest a potential advantage for M. abscessus under certain clinical conditions.