THE BACILLUS-SUBTILIS-SIGL GENE ENCODES AN EQUIVALENT OF SIGMA-54 FROM GRAM-NEGATIVE BACTERIA
THE BACILLUS-SUBTILIS-SIGL GENE ENCODES AN EQUIVALENT OF SIGMA-54 FROM GRAM-NEGATIVE BACTERIA
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DOI：
10.1073/pnas.88.20.9092
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发表时间：
1991-10-01
影响因子：
11.1
通讯作者：
RAPOPORT, G
中科院分区：
文献类型：
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作者：
DEBARBOUILLE, M;MARTINVERSTRAETE, I;RAPOPORT, G
枯草芽孢杆菌中的果聚糖酶操纵子由-12、-24启动子表达，并且转录由调节子LevR刺激，所述调节子LevR含有与NifA和NtrC家族调节子的中心结构域同源的结构域。我们分离出果聚糖酶操纵子表达缺陷的突变体。这些菌株含有定义一个基因的突变，该基因被称为sigL，位于遗传图谱上的cysB和sacB之间。对sigL基因进行克隆和测序。它编码一种含有436个残基的多肽，分子量为49，644。SigL的氨基酸序列与来自革兰氏阴性细菌的所有σ-54因子同源，包括苜蓿根瘤菌（Rhizobium meliloti）（32%同一性）和肺炎克雷伯菌（Klebsiella pneumoniae）（30%同一性）。B。枯草杆菌sigL突变体具有多效性表型：（i）果聚糖酶操纵子的转录强烈降低，和（ii）在缺乏氨的基本培养基中，当精氨酸、鸟氨酸、异亮氨酸或缬氨酸是唯一的氮源时，sigL突变体不能生长。这些结果表明sigL基因编码B中的sigma-54因子的等价物。枯草芽孢杆菌，据我们所知，这是第一个在革兰氏阳性菌中鉴定出的这种类型。
The levanase operon in Bacillus subtilis is expressed from a -12, -24 promoter and transcription is stimulated by the regulator LevR, which contains a domain homologous with the central domain of the NifA and NtrC family of regulators. We isolated mutants defective in the expression of the levanase operon. These strains contain mutations that define a gene, called sigL, located between cysB and sacB on the genetic map. The sigL gene was cloned and sequenced. It encodes a polypeptide containing 436 residues with a molecular weight of 49,644. The amino acid sequence of SigL is homologous with all sigma-54 factors from Gram-negative bacteria, including Rhizobium meliloti (32% identity) and Klebsiella pneumoniae (30% identity). B. subtilis sigL mutants have a pleiotropic phenotype: (i) the transcription of the levanase operon is strongly reduced and (ii) in minimal medium lacking ammonia, sigL mutants cannot grow when arginine, ornithine, isoleucine, or valine is the sole nitrogen source. These results indicate that the sigL gene encodes an equivalent of the sigma-54 factor in B. subtilis, to our knowledge, the first of this type to be identified in Gram-positive bacteria.