A hormogonium regulating locus, hrmUA, of the cyanobacterium Nostoc punctiforme strain ATCC 29133 and its response to an extract of a symbiotic plant partner Anthoceros punctatus
A hormogonium regulating locus, hrmUA, of the cyanobacterium Nostoc punctiforme strain ATCC 29133 and its response to an extract of a symbiotic plant partner Anthoceros punctatus
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DOI：
10.1094/mpmi.1997.10.2.280
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发表时间：
1997-03-01
影响因子：
3.5
通讯作者：
Meeks, JC
中科院分区：
文献类型：
--
作者：
Cohen, MF;Meeks, JC
转座子产生的点状念珠藻菌株ATCC 29133的突变菌株UCD 328具有对由共生植物伴侣Anthoceros punctatus分泌的激素诱导因子的敏感性增加的表型，以及植物的初始增加的激素依赖性感染。序列分析表明，菌株UCD 328中的转座位点位于1，251-bp的开放阅读框（ORF）内，命名为hrmA，与已知数据库序列无显著相似性。第二个837-bp ORF（hrmU）在hrmA起始处5'端2bp处结束，并具有属于NAD（P）H依赖性氧化还原酶家族的特征序列。在hrmU或hrmA中具有插入突变的菌株再现菌株UCD 328表型，luxAB与hrmU或hrmA的转录融合显示8- 10 - 100 μ g/ml的表达。在A的水提取物存在下，孵育开始后13至20小时荧光素酶活性的倍峰增加。斑点状。由提取物诱导的启动子被推断为从hrmU的翻译起始处2.0至3.4kb之间。在6.2kb片段内含有hrmUA的多拷贝质粒赋予野生型N. punctiforme 29133.该质粒和另一个在转座位点5'端含有11.4 kb DNA的质粒阻止了菌株UCD 328中hrmA-luxAB转录的提取依赖性诱导，这表明克隆片段滴定了一些反式激活因子。我们假设hrmUA的作用是通过一种未知的激素调节代谢物的代谢来抑制激素的形成。
Transposon-generated mutant strain UCD 328 of Nostoc punctiforme strain ATCC 29133 has a phenotype of an increased sensitivity to a hormogonium-inducing factor exuded by a symbiotic plant partner, Anthoceros punctatus, and an initial increased hormogonium-dependent infection of the plant. Sequence analysis showed that the transposition site in strain UCD 328 lies within a 1,251-bp open reading frame (ORF), designated hrmA, that displays no significant similarity to known database sequences. A second, 837-bp ORF (hrmU) ends 2 bp 5' from the start of hrmA and has the signature sequences belonging to a family of NAD(P)H-dependent oxidoreductases, Strains having insertional mutations in hrmU or hrmA reproduce the strain UCD 328 phenotype, Transcriptional fusions of luxAB to hrmU or hrmA show an 8- to 10-fold peak increase in luciferase activity 13 to 20 h after the start of incubation in the presence of an aqueous extract of A. punctatus. A promoter induced by the extract was deduced to be between 2.0 to 3.4 kb from the translational start of hrmU. A multicopy plasmid that contains hrmUA within a 6.2-kb fragment conferred an increased infection phenotype on wild-type N. punctiforme 29133. This plasmid and another plasmid containing 11.4 kb of DNA 5' of the transposition site prevented extract-dependent induction of hrmA-luxAB transcription in strain UCD 328, implicating titration of some trans-activator(s) by the cloned fragments. We hypothesize a role for hrmUA in the inhibition of hormogonium formation by the metabolism of an unknown hormogonium-regulating metabolite.