The ytkD (mutTA) gene of Bacillus subtilis encodes a functional antimutator 8-Oxo-(dGTP/GTP)ase and is under dual control of sigma A and sigma F RNA polymerases.
The regulation of expression of ytkD, a gene that encodes the first functional antimutator 8-oxo-dGTPase activity of B. subtilis, was studied here. A ytkD-lacZ fusion integrated into the ytkD locus of wild-type B. subtilis 168 revealed that this gene is expressed during both vegetative growth and early stages of sporulation. In agreement with this result, ytkD mRNAs were detected by both Northern blotting and reverse transcription-PCR during both developmental stages. These results suggested that ytkD is transcribed by the sequential action of RNA polymerases containing the sigma factors sigma(A) and sigma(F), respectively. In agreement with this suggestion, the spore-associated expression was almost completely abolished in a sigF genetic background but not in a B. subtilis strain lacking a functional sigG gene. Primer extension analysis mapped transcriptional start sites on mRNA samples isolated from vegetative and early sporulating cells of B. subtilis. Inspection of the sequences lying upstream of the transcription start sites revealed the existence of typical sigma(A)- and sigma(F)-type promoters. These results support the conclusion that ytkD expression is subjected to dual regulation and suggest that the antimutator activity of YtkD is required not only during vegetative growth but also during the early sporulation stages and/or germination of B. subtilis. While ytkD expression obeyed a dual pattern of temporal expression, specific stress induction of the transcription of this gene does not appear to occur, since neither oxidative damage (following either treatment with paraquat or hydrogen peroxide) nor mitomycin C treatment or sigma(B) general stress inducers (sodium chloride, ethanol, or heat) affected the levels of the gene product produced.
Ramírez
Martha I
MI
Institute of Investigation in Experimental Biology, Faculty of Chemistry, University of Guanajuato, Guanajuato Gto. 36050, Mexico.
Castellanos-Juárez
Francisco X
FX
Yasbin
Ronald E
RE
Pedraza-Reyes
Mario
M
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics*; D001426:Bacterial Proteins / Q000502:physiology*; D001430:Bacteriocins; D045643:DNA Repair Enzymes; D029968:Escherichia coli Proteins / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism*; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D010455:Peptides / Q000235:genetics*; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics*; D011755:Pyrophosphatases; D013014:SOS Response, Genetics; D012808:Sigma Factor / Q000502:physiology*; D013171:Spores, Bacterial / Q000502:physiology; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D001430:Bacteriocins; D029968:Escherichia coli Proteins; C064971:FliA protein, Bacteria; D010455:Peptides; D012808:Sigma Factor; C110490:mutacin II prepeptide, bacteria; C057674:8-hydroxyguanosine triphosphate; D006160:Guanosine Triphosphate; D010744:Phosphoric Monoester Hydrolases; D011755:Pyrophosphatases; C052211:mutT protein, E coli; C078207:8-oxodGTPase; D045643:DNA Repair Enzymes