Disease relevance of sigF

• Using PCR amplification with degenerate primers, we identified and cloned a sigma factor gene, sigF, from Mycobacterium tuberculosis [1].
• RNase protection assays revealed that M. tuberculosis sigF mRNA is not present during exponential-phase growth in M. bovis BCG cultures but is strongly induced during stationary phase, nitrogen depletion, and cold shock [1].
• The sigF gene has been overexpressed in Escherichia coli, purified, and used to raise polyclonal antibodies [2].

High impact information on sigF

• Weak expression of M. tuberculosis sigF was also detected during late-exponential phase, oxidative stress, anaerobiasis, and alcohol shock [1].
• Additionally, the DeltasigF mutant displayed diminished uptake of chenodeoxycholate, and this effect was reversed by complementation with a wild-type sigF gene [3].
• These data indicate that M. tuberculosis sigF is a nonessential alternate sigma factor both in axenic culture and for survival in macrophages in vitro [3].
• Determination of conditions of sigF expression is an important step in understanding the conditional gene regulation which may govern such processes as virulence and dormancy in mycobacteria [4].
• Primer extension analysis of the usfXp1 promoter in the E. coli two-plasmid system after IPTG-induced expression of M. tuberculosis sigF revealed a transcription start point that was identical as in M. tuberculosis [5].

Biological context of sigF

• A second open reading frame called usfY precedes usfX, but has no significant homologues and may not be contranscribed with the usfX and sigF [2].

Associations of sigF with chemical compounds

• Expression of the M. tuberculosis sigmaF encoded by sigF gene was under the control of the isopropyl beta-D-thiogalactopyranoside (IPTG)-dependent Ptrc promoter [5].

Analytical, diagnostic and therapeutic context of sigF

• Southern blot surveys with a sigF-specific probe identified cross-hybridizing bands in other slow-growing mycobacteria, Mycobacterium bovis bacille Calmette-Guérin (BCG) and Mycobacterium avium, but not in the rapid-growers Mycobacterium smegmatis or Mycobacterium abscessus [1].
• The induction of sigF following antibiotic exposure suggests that this bacterial transcription factor may control genes which are important for mycobacterial persistence in the host during chemotherapy [4].
• Sequence analysis suggests that the usfX and sigF genes appear to be cotranscribed and translationally coupled [2].

References