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Transcription of the Lysine-2,3-Aminomutase Gene in the kam Locus of Bacillus thuringiensis subsp. kurstaki HD73 Is Controlled by Both σ54 and σK Factors

Zhang, Zhe, Yang, Min, Peng, Qi, Wang, Guannan, Zheng, Qingyun, Zhang, Jie, Song, Fuping
Journal of bacteriology 2014 v.196 no.16 pp. 2934-2943
Bacillus thuringiensis subsp. kurstaki, bacteriology, beta-galactosidase, binding sites, complementary DNA, homologous recombination, loci, lysine, mutants, operon, rapid amplification of cDNA ends, reverse transcriptase polymerase chain reaction, sporulation, transcription (genetics), transcription factors
Lysine 2,3-aminomutase (KAM; EC catalyzes the interconversion of l-lysine and l-β-lysine. The transcription and regulation of the kam locus, including lysine-2,3-aminomutase-encoding genes, in Bacillus thuringiensis were analyzed in this study. Reverse transcription-PCR (RT-PCR) analysis revealed that this locus forms two operons: yodT (yodT-yodS-yodR-yodQ-yodP-kamR) and kamA (kamA-yokU-yozE). The transcriptional start sites (TSSs) of the kamA gene were determined using 5′ rapid amplification of cDNA ends (RACE). A typical −12/−24 σ54 binding site was identified in the promoter PkamA, which is located upstream of the kamA gene TSS. A β-galactosidase assay showed that PkamA, which directs the transcription of the kamA operon, is controlled by the σ54 factor and is activated through the σ54-dependent transcriptional regulator KamR. The kamA operon is also controlled by σK and regulated by the GerE protein in the late stage of sporulation. kamR and kamA mutants were prepared by homologous recombination to examine the role of the kam locus. The results showed that the sporulation rate in B. thuringiensis HD(ΔkamR) was slightly decreased compared to that in HD73, whereas that in HD(ΔkamA) was similar to that in HD73. This means that other genes regulated by KamR are important for sporulation.