Repression of the cob operon of Salmonella typhimurium by adenosylcobalamin is influenced by mutations in the pdu operon.
Repression of the cob operon of Salmonella typhimurium by adenosylcobalamin is influenced by mutations in the pdu operon.
复制标题
腺苷钴胺素对鼠伤寒沙门氏菌 cob 操纵子的抑制受到 pdu 操纵子突变的影响。
DOI：
10.1128/jb.179.19.6084-6091.1997
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发表时间：
1997
影响因子：
3.2
通讯作者：
Roth,JR
中科院分区：
文献类型：
--
作者：
Ailion,M;Roth,JR
cob操纵子编码腺苷钴胺素（adenosylbobalamin，B12）生物合成所需的功能。丙二醇诱导cob操纵子和邻近的pdu操纵子的转录，pdu操纵子编码用于丙二醇的B12依赖性降解的蛋白质。cob操纵子（而不是pdu）的表达被外源性氰钴胺抑制。提供的证据表明，cob操纵子阻遏信号由内部产生的cob-B12，它可以形成由CobA腺苷转移酶或由一个替代的腺苷转移酶（cobT），我们推断是编码内的pdu操纵子。抑制也受到pdu操纵子中的突变（padB）的影响，所述pdu操纵子映射推断的pdu腺苷转移酶基因的上游。这种突变允许钴胺素以比野生型所需浓度低100倍的浓度介导阻遏。有人提出，这些突变消除了一个组成部分的丙二醇脱氢酶酶复合物（PduCDE），这种复杂的竞争与玉米穗轴调控机制的有限供应的β-B12。
The cob operon encodes functions needed for the biosynthesis of adenosylcobalamin (Ado-B12). Propanediol induces transcription of the cob operon and the neighboring pdu operon, which encodes proteins for the B12-dependent degradation of propanediol. Expression of the cob (but not the pdu) operon is repressed by exogenous cyanocobalamin. Evidence is provided that cob operon repression is signaled by internally generated Ado-B12, which can be formed either by the CobA adenosyltransferase or by an alternative adenosyltransferase (AdoT) that we infer is encoded within the pdu operon. Repression is also affected by mutations (AdoB) in the pdu operon that map upstream of the inferred pdu adenosyltransferase gene. Such mutations allow cobalamin to mediate repression at concentrations 100-fold lower than those needed in the wild type. It is proposed that these mutations eliminate a component of the propanediol dehydratase enzyme complex (PduCDE) and that this complex competes with the cob regulatory mechanism for a limited supply of Ado-B12.