• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Applied and Environmental Microbiology >DNA Sequence and Mutational Analysis of Rhizobitoxine Biosynthesis Genes in Bradyrhizobium elkanii
【24h】

DNA Sequence and Mutational Analysis of Rhizobitoxine Biosynthesis Genes in Bradyrhizobium elkanii

机译：拟南芥根瘤菌生物合成基因的DNA序列及突变分析

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

We cloned and sequenced a cluster of genes involved in the biosynthesis of rhizobitoxine, a nodulation enhancer produced by Bradyrhizobium elkanii. The nucleotide sequence of the cloned 28.4-kb DNA region encompassing rtxAshowed that several open reading frames (ORFs) were located downstream of rtxA. A large-deletion mutant of B. elkanii, USDA94Δrtx::Ω1, which lacks rtxA, ORF1 (rtxC), ORF2, and ORF3, did not produce rhizobitoxine, dihydrorhizobitoxine, or serinol. The broad-host-range cosmid pLAFR1, which contains rtxAand these ORFs, complemented rhizobitoxine production in USDA94Δrtx::Ω1. Further complementation experiments involving cosmid derivatives obtained by random mutagenesis with a kanamycin cassette revealed that at least rtxAand rtxC are necessary for rhizobitoxine production. Insertional mutagenesis of the N-terminal and C-terminal regions ofrtxA indicated that rtxA is responsible for two crucial steps, serinol formation and dihydrorhizobitoxine biosynthesis. An insertional mutant of rtxC produced serinol and dihydrorhizobitoxine but no rhizobitoxine. Moreover, thertxC product was highly homologous to the fatty acid desaturase of Pseudomonas syringae and included the copper-binding signature and eight histidine residues conserved in membrane-bound desaturase. This result suggested thatrtxC encodes dihydrorhizobitoxine desaturase for the final step of rhizobitoxine production. In light of results from DNA sequence comparison, gene disruption experiments, and dihydrorhizobitoxine production from various substrates, we discuss the biosynthetic pathway of rhizobitoxine and its evolutionary significance in bradyrhizobia.
机译：我们克隆并测序了与根瘤菌生物合成有关的基因簇，该基因是由根瘤菌根瘤菌产生的结瘤增强剂。克隆的包含rtxA的28.4kb DNA区域的核苷酸序列表明，几个开放阅读框（ORF）位于rtxA的下游。缺少rtxA，ORF1（rtxC），ORF2和ORF3的B.elkanii大缺失突变体USDA94Δrtx::Ω1不产生根瘤菌素，二氢根瘤菌素或丝氨醇。包含rtxA和这些ORF的广泛宿主粘粒pLAFR1补充了USDA94Δrtx::Ω1中的根除二恶英的生产。进一步的互补实验涉及通过与卡那霉素盒的随机诱变获得的粘粒衍生物，这表明至少需要rtxA和rtxC才能生产根硫bit定。 rtxA的N端和C端区域的插入诱变表明rtxA负责两个关键步骤，丝氨醇的形成和二氢噻唑啉酮的生物合成。 rtxC的插入突变体产生丝氨醇和二氢根除胆碱，但没有根除胆碱。而且，rtxC产物与丁香假单胞菌的脂肪酸去饱和酶高度同源，并且包括铜结合的特征和膜结合的去饱和酶中保守的八个组氨酸残基。该结果表明，rtxC编码二氢根除胆碱的去饱和酶，用于生产根除胆碱的最后一步。根据DNA序列比较，基因破坏实验和从各种底物中产生双氢根除胆碱的结果，我们讨论了根除胆碱的生物合成途径及其在缓生根瘤菌中的进化意义。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号