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首页> 外文期刊>Journal of bacteriology >The control region of the pdu/cob regulon in Salmonella typhimurium.
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The control region of the pdu/cob regulon in Salmonella typhimurium.

机译：鼠伤寒沙门氏菌中pdu / cob regulon的控制区。

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摘要

The pdu operon encodes proteins for the catabolism of 1,2-propanediol; the nearby cob operon encodes enzymes for the biosynthesis of adenosyl-cobalamin (vitamin B12), a cofactor required for the use of propanediol. These operons are transcribed divergently from distinct promoters separated by several kilobases. The regulation of the two operons is tightly integrated in that both require the positive activator protein PocR and both are subject to global control by the Crp and ArcA proteins. We have determined the DNA nucleotide sequences of the promoter-proximal portion of the pdu operon and the region between the pdu and cob operons. Four open reading frames have been identified, pduB, pduA, pduF, and pocR. The pduA and pduB genes are the first two genes of the pdu operon (transcribed clockwise). The pduA gene encodes a hydrophobic protein with 56% amino acid identity to a 10.9-kDa protein which serves as a component of the carboxysomes of several photosynthetic bacteria. The pduF gene encodes a hydrophobic protein with a strong similarity to the GlpF protein of Escherichia coli, which facilitates the diffusion of glycerol. The N-terminal end of the PduF protein includes a motif for a membrane lipoprotein-lipid attachment site as well as a motif characteristic of the MIP (major intrinsic protein) family of transmembrane channel proteins. We presume that the PduF protein facilitates the diffusion of propanediol. The pocR gene encodes the positive regulatory protein of the cob and pdu operons and shares the helix-turn-helix DNA binding motif of the AraC family of regulatory proteins. The mutations cobR4 and cobR58 cause constitutive, pocR-independent expression of the cob operon under both aerobic and anaerobic conditions. Evidence that each mutation is a deletion creating a new promoter near the normal promoter site of the cob operon is presented.
机译：pdu操纵子编码用于1,2-丙二醇分解代谢的蛋白质;附近的芯子操纵子编码用于腺苷-钴胺素（维生素B12）生物合成的酶，这是使用丙二醇所需的辅助因子。这些操纵子从不同的启动子发散地转录，这些启动子相隔几千个碱基。两个操纵子的调节紧密结合，因为它们都需要阳性激活蛋白PocR，并且都受到Crp和ArcA蛋白的全局控制。我们已经确定了pdu操纵子的启动子附近部分的DNA核苷酸序列以及pdu和cob操纵子之间的区域。已经确定了四个开放阅读框，pduB，pduA，pduF和pocR。 pduA和pduB基因是pdu操纵子的前两个基因（顺时针转录）。 pduA基因编码的疏水蛋白与10.9-kDa蛋白具有56％的氨基酸同一性，后者是几种光合作用细菌的羧基体的组成部分。 pduF基因编码的疏水蛋白与大肠杆菌的GlpF蛋白具有很强的相似性，从而促进甘油的扩散。 PduF蛋白的N末端包括膜脂蛋白-脂质附着位点的基序以及跨膜通道蛋白的MIP（主要内在蛋白）家族的特征基序。我们假定PduF蛋白促进丙二醇的扩散。 pocR基因编码cob和pdu操纵子的正调控蛋白，并共享AraC调控蛋白家族的螺旋-转-螺旋DNA结合基序。突变cobR4和cobR58在好氧和厌氧条件下均导致组成型，独立于pocR的cob操纵子表达。提供了每个突变都是缺失的证据，该突变在芯棒操纵子的正常启动子位点附近产生了新的启动子。

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