A transcript cleavage factor of Mycobacterium tuberculosis important for its survival

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Transcription involves proteins like Gre factors that modify RNA polymerase (RNAP) during elongation and termination.
• Gre factors regulate transcription by interacting with RNAP's active center, promoting RNA hydrolysis in backtracked complexes.

Purpose of the Study:

• To investigate the function of Rv1080c (MtbGre), a putative Gre factor in Mycobacterium tuberculosis.
• To determine if MtbGre can complement or rescue transcription defects in Escherichia coli.

Main Methods:

• Characterization of MtbGre's effect on promoter clearance, abortive transcription, and arrested/paused elongation complexes.
• Complementation assays using E. coli gre-deficient strains.
• Assessment of MtbGre's ability to rescue stalled E. coli RNAP elongation complexes.

Main Results:

• MtbGre enhanced promoter clearance and rescued paused complexes on mycobacterial templates.
• MtbGre could not complement E. coli gre-deficient strains or rescue stalled E. coli RNAP.
• MtbGre is essential for Mycobacterium tuberculosis survival.
• A second Gre homolog, Rv3788, lacked transcript cleavage activity.

Conclusions:

• MtbGre plays an essential role in Mycobacterium tuberculosis transcription and survival.
• Functional differences between MtbGre and E. coli Gre factors indicate species-specific interactions are crucial for transcript cleavage.
• A single functional Gre factor appears sufficient for M. tuberculosis genome transcription.