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首页> 外文期刊>Journal of bacteriology >Role of Alternative ? Factor AlgU in Encystment of Azotobacter vinelandii
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Role of Alternative ? Factor AlgU in Encystment of Azotobacter vinelandii

机译:替代角色?葡萄固氮囊泡中的因子AlgU

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摘要

Alginate is essential for encystment in Azotobacter vinelandii. Transcription of the algD gene, which codes for GDP-mannose dehydrogenase, a key enzyme in the alginate biosynthetic pathway, is initiated at two promoters, one of which, p2, has ?E consensus sequences. AlgU is the A. vinelandii alternative ?E factor. In this study, we constructed an algU mutant (SMU88) which, as expected, is impaired in alginate production, encystment, and transcription of thealgD gene from the p2 promoter. Plasmid pJMSAT1, carrying the A. vinelandii algU gene, restored alginate production and encystment to SMU88 and to strain UW136, a naturally occurringalgU mutant. Plasmid pSMU865, carrying the A. vinelandii mucABCD genes coding for negative regulators of AlgU activity and previously shown to diminish alginate production in the wild-type strain, ATCC 9046, was shown here to impair encystment and transcription of the algD gene from the p2algU-dependent promoter. Since nonencysting strain ATCC 9046/pSMU865 produced more alginate than some encysting strains, such as UW136/pJMSAT1, we propose an AlgU role in encystment, independent of the structural role that alginate plays in mature cysts.
机译:海藻酸盐对于葡萄固氮菌的包囊是必不可少的。编码GDP-甘露糖脱氢酶(藻酸盐生物合成途径中的关键酶)的 algD 基因的转录起始于两个启动子,其中一个启动子p2具有? E 共有序列。 AlgU是 A。 vinelandii 替代? E 因子。在这项研究中,我们构建了一个 algU 突变体(SMU88),正如预期的那样,该突变体在藻酸盐的产生,包囊化和 algD 基因从p2启动子的转录中受到损害。携带 A的质粒pJMSAT1。 vinelandii algU 基因可将藻酸盐的产生和囊化恢复到SMU88和UW136菌株中,该菌株是天然存在的 algU 突变体。携带 A的质粒pSMU865。编码AlgU活性负调节剂的vinelandii mucABCD 基因,以前显示其会减少野生型ATCC 9046菌株中的藻酸盐生成,从而削弱 algD 基因的囊化和转录来自p2 algU 依赖性启动子。由于非输入菌株ATCC 9046 / pSMU865产生的藻酸盐比某些输入菌株(例如UW136 / pJMSAT1)要多,因此我们建议AlgU在包囊中的作用独立于藻酸盐在成熟囊肿中的结构作用。

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