A novel sigma factor reveals a unique regulon controlling cell-specific recombination in Mycoplasma genitalium.
Bottom Line: Herein, we found that MG428 activates transcription of recA, ruvA and ruvB as well as several genes with unknown function.Additionally, MG428 was found to interact with the RNAP core enzyme, reinforcing the predicted role of this protein as an alternative sigma factor.Finally, our results indicate that MG428 contributes to the generation of genetic diversity in this model organism.
Affiliation: Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular. Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.Show MeSH
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Mentions: To monitor the expression of MG428 and RecA in the population of M. genitalium, mutants carrying MG428-, RecA- or a control Cat-mCherry fusion (Supplementary Figure S6) were obtained by allelic exchange. Several clones of each mutant strain were analyzed by fluorescence microscopy (Figure 7 and Table 2). As expected, expression of the Cat-mCherry fusion under the control of an endogenous M. genitalium promoter was detected in virtually the entire population. In contrast, only a 0.46% of the cells carrying the MG428-mCherry fusion exhibited detectable fluorescence. Likewise, the RecA-mCherry fluorescence was detected in a 0.66% of the population. Interestingly, mCherry fluorescence was usually observed in cell pairs (Figure 7), suggesting a spatial association between mycoplasmas with increased levels of MG428 or RecA. In addition, we explored RecA-mCherry expression in a ΔMG_428 mutant background. This strain was obtained by deleting the MG_428 gene from the mutant carrying the RecA-mCherry fusion (Supplementary Figure S6). We could not detect any fluorescent cell in any of the clones analyzed, demonstrating that the presence of the MG_428 gene was necessary for RecA expression at high levels.
Affiliation: Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular. Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.