ANALYSIS OF A HET(-) MUTATION IN ANABAENA SP STRAIN PCC-7120 IMPLICATES A SECONDARY METABOLITE IN THE REGULATION OF HETEROCYST SPACING
ANALYSIS OF A HET(-) MUTATION IN ANABAENA SP STRAIN PCC-7120 IMPLICATES A SECONDARY METABOLITE IN THE REGULATION OF HETEROCYST SPACING
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DOI：
10.1128/jb.176.8.2282-2292.1994
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发表时间：
1994-04-01
影响因子：
3.2
通讯作者：
WOLK, CP
中科院分区：
文献类型：
--
作者：
BLACK, TA;WOLK, CP
鱼腥藻菌株PCC 7120的转座子产生的突变体N10具有Het（-）表型（A. Ernst，T.布莱克，Y.蔡杰M. Panoff，D. N. Tiwari和C. P. Wolk，J. Bacteriol. 174：6025-6032，1992）。转座子突变的重建再现了Het（-）表型，但是在转座子位置处具有其他插入的重建产生形成多个连续异型胞的菌株。转座子插入位点附近的序列分析表明，插入位于861-bp开放阅读框（ORF）（hetN）的5'端。hetN的翻译产物（HetN）显示出与NAD（P）H依赖性氧化还原酶的广泛相似性，所述NAD（P）H依赖性氧化还原酶参与脂肪酸、聚-β-羟基丁酸酯、结瘤因子和聚酮化合物的生物合成。第二个1，518-bp的ORF（hetM）从hetN的起始处5'结束556 bp，似乎编码具有至少两个功能结构域的蛋白质：其氨基末端类似于酰基载体蛋白，而其中心部分类似于进行还原反应的蛋白质的结构域。第三个711-bp的ORF（hetI）编码在相对链上，距离hetN的3'端42 bp。由hetI编码的蛋白质HetI类似于枯草芽孢杆菌的Sfp和大肠杆菌的EntD，这些蛋白质是环肽生物合成或输出所需的。来自含有hetN的野生型DNA的EMDA-EMBL 3文库的克隆不与N10中的hetN：：Tn 5 -1063突变互补。hetN作为复制质粒上唯一的ORF，其存在抑制了野生型细胞中异型胞的形成，而hetI的额外存在则增强了这种效应。
Transposon-generated mutant N10 of Anabaena sp. strain PCC 7120 has a Het(-) phenotype (A. Ernst, T. Black, Y. Cai, J.-M. Panoff, D. N. Tiwari, and C. P. Wolk, J. Bacteriol. 174:6025-6032, 1992). Reconstruction of the transposon mutation reproduced a Het(-) phenotype, but reconstructions with other insertions at the position of the transposon produced strains that form multiple contiguous heterocysts. Sequence analysis around the site of insertion of the transposon showed that the insertion lies within the 5' end of an 861-bp open reading frame (ORF) (hetN). The product of translation of hetN (HetN) shows extensive similarity to NAD(P)H-dependent oxidoreductases that are involved in biosyntheses of fatty acids, poly-beta-hydroxybutyrate, nod factor, and polyketides. A second, 1,518-bp ORF (hetM) that ends 556 bp 5' from the start of hetN appears to encode a protein that has at least two functional domains: its amino terminus is similar to an acyl carrier protein, while its central portion is similar to domains of proteins that perform reductive reactions. A third, 711-bp ORF (hetI) encoded on the opposite strand ends 42 bp away from the 3' end of hetN. The protein encoded by hetI, HetI, is similar to Sfp from Bacillus subtilis and EntD from Escherichia coli, proteins that are required for the biosynthesis or export of cyclic peptides. Clones from a lambda-EMBL3 library that contain the wild-type DNA for hetN do not complement the hetN::Tn5-1063 mutation in N10. The presence of hetN, as the only ORF, on a replicating plasmid suppresses heterocyst formation in wild-type cells, whereas the additional presence of hetI alleviates this effect.