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首页> 外文OA文献 >Glutathione is required for maximal transcription of the cobalamin biosynthetic and 1,2-propanediol utilization (cob/pdu) regulon and for the catabolism of ethanolamine, 1,2-propanediol, and propionate in Salmonella typhimurium LT2.
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Glutathione is required for maximal transcription of the cobalamin biosynthetic and 1,2-propanediol utilization (cob/pdu) regulon and for the catabolism of ethanolamine, 1,2-propanediol, and propionate in Salmonella typhimurium LT2.

机译：谷胱甘肽是钴胺素生物合成和1,2-丙二醇利用率（cob / pdu）调节剂的最大转录，以及鼠伤寒沙门氏菌LT2中乙醇胺，1,2-丙二醇和丙酸酯的分解代谢所必需的。

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摘要

Transcription of the cob/pdu regulon of Salmonella typhimurium is activated by the PocR regulatory protein in response to 1,2-propanediol (1,2-PDL) in the environment. Nutritional analysis and DNA sequencing confirmed that a strain defective in expression of the cob/pdu regulon in response to 1,2-PDL lacked a functional gshA gene. gshA encodes gamma-glutamylcysteine synthetase (L-glutamate:L-cysteine gamma-ligase [ADP forming]; EC 6.3.2.2), the enzyme that catalyzes the first step in the synthesis of glutathione (GSH). The DNA sequence of gshA was partially determined, and the location of gshA in the chromosome was established by two-factor crosses. P22 cotransduction of gshA with nearby markers showed 21% linkage to srl and 1% linkage to hyd; srl was 9% cotransducible with hyd. In light of these data, the gene order gshA srl hyd is suggested. The level of reduced thiols in the gshA strain was 87% lower than the levels measured in the wild-type strain in both aerobically and anaerobically grown cells. 1,2-PDL-dependent transcription of cob/pdu was studied by using M. Casadaban's Mu-lacZ fusions. In aerobically grown cells, transcription of a cbi-lacZ fusion (the cbi genes are the subset of cob genes that encode functions needed for the synthesis of the corrin ring) was 4-fold lower and transcription of a pdu-lacZ fusion was 10-fold lower in a gshA mutant than in the wild-type strain. Expression of the cob/pdu regulon in response to 1,2-PDL was restored when GSH was included in the medium. In anaerobically grown cells, cbi-lacZ transcription was only 0.4-fold lower than in the gshA+ strain; pdu-lacZ transcription was reduced only by 0.34-fold, despite the lower thiol levels in the mutant. cobA-lacZ transcription was used as negative control of gene whose transcription is not controlled by the PocR/1,2-PDL system; under both conditions, cobA transcription remained unaffected. The gshA mutant strain was unable to utilize 1,2-PDL, ethanolamine, or propionate as a carbon and energy source. The defect in ethanolamine utilization appears to be at the level of ethanolamine ammonia-lyase activity, not at the transcriptional level. Possible roles for GSH in ethanolamine, 1,2-PDL, and propionate catabolism are proposed and discussed.
机译：响应环境中的1,2-丙二醇（1,2-PDL），PocR调节蛋白激活鼠伤寒沙门氏菌的cob / pdu regulon的转录。营养分析和DNA测序证实，响应1，2-PDL的cob / pdu regulon表达缺陷的菌株缺乏功能性gshA基因。 gshA编码γ-谷氨酰半胱氨酸合成酶（L-谷氨酸：L-半胱氨酸γ-连接酶[ADP形成]； EC 6.3.2.2），该酶催化谷胱甘肽（GSH）合成的第一步。 gshA的DNA序列已部分确定，并且gshA在染色体中的位置是通过两因素杂交确定的。 gshA与附近标记物的P22共转导显示与srl有21％的连锁，与hyd有1％的连锁。 srl与hyd可共转导9％。根据这些数据，提出了基因顺序gshA srl hyd。在需氧和需氧生长的细胞中，gshA菌株中还原的硫醇水平均比野生型菌株中测得的水平低87％。通过使用M. Casadaban的Mu-lacZ融合蛋白研究了1,2-PDL依赖的cob / pdu转录。在需氧生长的细胞中，cbi-lacZ融合体的转录（cbi基因是编码柯林环合成所需功能的cob基因的子集）的转录降低了4倍，而pdu-lacZ融合体的转录降低了10-与野生型菌株相比，gshA突变体的折叠倍数低。当培养基中包含GSH时，可恢复响应1,2-PDL的cob / pdu调节子的表达。在厌氧生长的细胞中，cbi-lacZ转录仅比gshA +菌株低0.4倍；尽管突变体中的硫醇水平较低，但pdu-lacZ转录仅降低了0.34倍。 cobA-lacZ转录用作该基因不受PocR / 1,2-PDL系统控制的基因的阴性对照。在两种情况下，cobA转录均不受影响。 gshA突变株无法利用1,2-PDL，乙醇胺或丙酸酯作为碳源和能源。乙醇胺利用中的缺陷似乎是在乙醇胺氨裂解酶活性的水平上，而不是在转录水平上。提出并讨论了GSH在乙醇胺，1,2-PDL和丙酸酯分解代谢中的可能作用。

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