High-throughput characterization of Mycobacterium tuberculosis gene function across diverse conditions

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• Mycobacterium tuberculosis (Mtb) causes chronic lung infections, but the genetic basis for its pathogenicity is not fully understood.
• Traditional genetic screening methods for Mtb have limited throughput, hindering large-scale functional genomics.
• A high-throughput method is needed to efficiently determine gene function in Mtb.

Purpose of the Study:

• To develop and apply a pooled random barcode transposon-site sequencing (RB-TnSeq) library for high-throughput genetic screening in Mtb.
• To elucidate the function of previously uncharacterized genes in Mtb, particularly the PE and PPE families.
• To investigate Mtb metabolism, stress responses, and antibiotic resistance mechanisms.

Main Methods:

• Generated a pooled random barcode transposon-site sequencing (RB-TnSeq) library for Mtb.
• Performed 95 RB-TnSeq screens across various carbon sources, nitrogen sources, stressors, and antibiotics.
• Analyzed the resulting dataset to identify gene-phenotype relationships.

Main Results:

• Uncovered 187 novel phenotypes for 37 PE and PPE family genes in Mtb.
• Proposed a lactate utilization pathway involving the ESX-5 secretion system and identified a candidate D-lactate dehydrogenase.
• Determined that Nuo, a proton-pumping NADH dehydrogenase, is essential for propionate utilization.
• Characterized a novel Mtb mutant exhibiting resistance to the tuberculosis antibiotic pretomanid.

Conclusions:

• The RB-TnSeq method provides a powerful tool for high-throughput genetic screening in Mtb.
• This study significantly expands the known functions of Mtb genes, particularly PE and PPE families.
• Findings offer new insights into Mtb metabolism, stress adaptation, and antibiotic resistance, paving the way for future research and therapeutic development.