6 NODULATION GENES OF NOD BOX LOCUS-4 IN RHIZOBIUM-MELILOTI ARE INVOLVED IN NODULATION SIGNAL PRODUCTION - NODM CODES FOR D-GLUCOSAMINE SYNTHETASE
6 NODULATION GENES OF NOD BOX LOCUS-4 IN RHIZOBIUM-MELILOTI ARE INVOLVED IN NODULATION SIGNAL PRODUCTION - NODM CODES FOR D-GLUCOSAMINE SYNTHETASE
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DOI：
10.1007/bf00282455
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发表时间：
1991-08-01
期刊：
影响因子：
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通讯作者：
KONDOROSI, A
中科院分区：
文献类型：
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作者：
BAEV, N;ENDRE, G;KONDOROSI, A
测定了苜蓿根瘤菌（Rhizobium meliloti）中结瘤盒基因座n4的核苷酸序列，结果显示有6个基因组成一个单一转录单元，这些基因可被植物信号（如木犀草素）诱导。这些基因的突变会影响苜蓿（Medicago）根瘤发育的早期阶段，但对苜蓿根瘤菌的另一个宿主草木樨（Melilotus）没有可检测到的影响。根据序列同源性，第一个开放阅读框（ORF）对应于豌豆根瘤菌（Rhizobium leguminosarum）的nodM基因，最后一个对应于nodN基因。其他基因与目前已测序的任何基因均无相似性，因此我们分别将它们命名为nolF、nolG、nolH和nolI。我们发现n4基因座，尤其是nodM和nodN基因，参与了根毛变形（Had）因子的产生。NodM与氨基转移酶具有同源性，主要与大肠杆菌（Escherichia coli）的glmS基因编码的D - 氨基葡萄糖合成酶同源。我们证明在大肠杆菌中，调控基因nodD与木犀草素一起可激活nod基因。在此基础上，我们表明nodM可弥补大肠杆菌的glmS - 突变，这表明在植物信号控制下，nodM可被视为一个glmS基因。此外，外源提供的D - 氨基葡萄糖可恢复nodM突变体对苜蓿的结瘤能力。我们的数据表明，除了苜蓿根瘤菌的管家基因glmS外，作为第二个glmS拷贝的nodM为Had因子的合成提供了足够量的氨基葡萄糖。
The nucleotide sequence of the nod box locus n4 in Rhizobium meliloti was determined and revealed six genes organized in a single transcriptional unit, which are induced in response to a plant signal such as luteolin. Mutations in these genes influence the early steps of nodule development on Medicago, but have no detectable effect on Melilotus, another host for R. meliloti. Based on sequence homology, the first open reading frame (ORF) corresponds to the nodM gene and the last to the nodN gene of Rhizobium leguminosarum. The others do not exhibit similarity to any genes sequenced so far, so we designated them as nolF, nolG, nolH and nolI, respectively. We found that the n4 locus, and especially the nodM and nodN genes, are involved in the production of the root hair deformation (Had) factor. NodM exhibits homology to amidotransferases, primarily to the D-glucosamine synthetase encoded by the glmS gene of Escherichia coli. We demonstrated that in E. coli the regulatory gene nodD together with luteolin can activate nod genes. On this basis we showed that nodM complemented an E. coli glmS- mutation, indicating that nodM can be considered as a glmS gene under plant signal control. Moreover, exogenously supplied D-glucosamine restored nodulation of Medicago by nodM mutants. Our data suggest that in addition to the housekeeping glmS gene of R. meliloti, nodM as a second glmS copy provides glucosamine in sufficient amounts for the synthesis of the Had factor.