Physical maps of the rfa loci of Escherichia coli K-12 and Salmonella typhimurium.
Physical maps of the rfa loci of Escherichia coli K-12 and Salmonella typhimurium.
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大肠杆菌 K-12 和鼠伤寒沙门氏菌 rfa 位点的物理图谱。
DOI：
10.1128/jb.173.23.7410-7411.1991
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发表时间：
1991
影响因子：
3.2
通讯作者：
MacClachlan,PR
中科院分区：
文献类型：
--
作者：
Schnaitman,CA;Parker,CT;Klena,JD;Pradel,EL;Pearson,NB;Sanderson,KE;MacClachlan,PR
大肠杆菌K-12图谱（3）min 81和鼠伤寒沙门氏菌图谱（14）min 79处的rfa基因座是参与脂多糖核心区合成的基因簇。该位点基因的功能已被广泛研究（综述见参考文献11和13）。这两种生物体的rfa基因座已被克隆并部分测序，两种生物体的测序区域有足够的重叠，使我们能够组装基因座的物理图谱（图1）。在大肠coli K-12中，kbl（1）基因的序列（位于该基因座左侧的侧翼）以及fpg（4）和rpmBG（10）基因的序列（位于该基因座右侧的侧翼）已被公布。沙门氏菌基因rfaD、-F、-C、-L、-K、-J和-I通过携带rfa限制性片段的质粒互补标准沙门氏菌突变的能力被分配到开放阅读框，并且这些基因的转录方向和限制都另外通过质粒插入物的转座子诱变来限定。对E.大肠杆菌K-12 rfaD中已描述（12）。E.大肠杆菌基因rfaF、-C、-L、-K、-Z和-Y通过衍生的蛋白质序列与它们的沙门氏菌对应物的同源性来鉴定。E.大肠杆菌rfaK、-B、-P和-G基因通过用大肠杆菌完成标准沙门氏菌突变来定位。coli质粒导入S.鼠伤寒沙门氏菌。通过将体外构建的突变体与E. coli染色体。克隆、测序、序列比较和完成研究的实验细节将在别处描述。E.沙门氏菌基因rfal和rfal-J的大肠杆菌K-12对应物由于两种生物体之间己糖区结构的差异而存在问题（关于该问题的讨论，参见参考文献2，p.5315 - 5316）。由于这些基因被认为在两种生物中编码不同的糖转移酶，因此提出了E。coliK-12基因命名为rfaM和-N（2，7）。然而，在E. coliK-12中与S.鼠伤寒沙门氏菌与沙门氏菌rfal和-J在蛋白质水平上具有相当大的同源性。typhimurium（5）和E. coliK-12与S.鼠伤寒。因此，这对基因似乎是非常相似的结构和功能，即使他们表现出不同的糖specificites，并在此基础上，我们建议他们被称为rfaI和-J的两种生物。一些开放的阅读框架，没有正确的-
The rfa loci at min 81 of the Escherichia coli K-12 map (3) and min 79 of the Salmonella typhimurium map (14) are clusters of genes involved in synthesis of the core region of lipopolysaccharide. The functions ofgenes at this locus have been extensively studied (for reviews, see references 11 and 13). The rfa loci of the two organisms have been cloned and partially sequenced, and there is enough overlap of sequenced regions from both organisms to allow us to assemble physical maps for the loci (Fig. 1). In E. coli K-12, the sequences of the kbl (1) gene, which flanks the locus to the left, and the fpg (4) and rpmBG (10) genes, which flank the locus to the right, have been published. The Salmonella genes rfaD,-F,-C,-L,-K,-J, and-I were assigned to open reading frames by the ability of plasmids bearing rfa restriction fragments to complement standard Salmonella mutations, and both the direction of transcription and the limits of these genes were additionally defined by transposon mutagenesis of the plasmid inserts. The sequence and assignment to an open reading frame of E. coli K-12 rfaD has been described (12). E. coli genes rfaF,-C,-L,-K,-Z, and-Y were identified by the homology of the derived protein sequences to those of their Salmonella counterparts. E. coli genes rfaK,-B,-P, and-G were assigned by comple-mentation of standard Salmonella mutations by E. coli plasmids introduced into S. typhimurium by electroporation. These assignments have also been confirmed by the phenotypes of mutants obtained by crossing mutations constructed in vitro into the E. coli chromosome. Experimental details of the cloning, sequencing, sequence comparison, and comple-mentation studies will be described elsewhere. Assignment of the E. coli K-12 counterparts of Salmonella genes rfal and-J presented a problem because of the difference in structure of the hexose region between the two organisms (for a discussion of this problem, see reference 2, p. 5315 to 5316). Since these genes are thought to encode different sugar transferases in the two organisms, it was proposed that the E. coli K-12 genes be designated rfaM and-N (2, 7). However, in E. coli K-12 the two genes which occupy the same positions with respect to flanking genes as rfaI and-J of S. typhimurium show considerable homology at the protein level to rfal and-J from S. typhimurium (5), and restriction fragments from E. coli K-12 which contained both of these genes complemented either rfaI or rfaJ mutants of S. typhimurium. Thus, these pairs of genes appear to be very similar in structure and function even though they exhibit different sugar specificites, and on this basis we propose that they be termed rfaI and-J for both organisms. A number of open reading frames which did not corre-