Bergström S, Lindberg F P, Olsson O, Normark S
J Bacteriol. 1983 Sep;155(3):1297-305. doi: 10.1128/jb.155.3.1297-1305.1983.
Specific DNA probes from Escherichia coli K-12 were used to analyze the sequence divergence of the frd and ampC operons in various species of gram-negative bacteria. These operons code for the fumarate reductase complex and the chromosomal beta-lactamase, respectively. We demonstrate that the two operons show the same general pattern of divergence, although the frd operon is considerably more conserved than is the ampC operon. The major exception is Salmonella typhimurium LT2, which shows a strong homology to the E. coli frd probe but none to the E. coli ampC probe. The operons from Citrobacter freundii and Shigella sonnei were cloned and characterized by physical mapping, Southern hybridization, and protein synthesis in minicells. In S. sonnei, as in E. coli K-12, the frd and ampC operons overlap (T. Grundström and B. Jaurin, Proc. Natl. Acad. Sci. U.S.A. 79:1111-1115, 1982). Only minor discrepancies between the two operons were found over the entire frd-ampC region. In C. freundii, the ampC and frd operons do not overlap, being separated by about 1,100 base pairs. Presumably the inducible property of the C. freundii chromosomal beta-lactamase is encoded by this 1,100-base-pair DNA segment.
利用来自大肠杆菌K-12的特异性DNA探针，分析革兰氏阴性菌不同菌种中frd和ampC操纵子的序列差异。这些操纵子分别编码延胡索酸还原酶复合物和染色体β-内酰胺酶。我们证明，尽管frd操纵子比ampC操纵子保守得多，但这两个操纵子呈现出相同的一般差异模式。主要的例外是鼠伤寒沙门氏菌LT2，它与大肠杆菌frd探针有很强的同源性，但与大肠杆菌ampC探针没有同源性。对弗氏柠檬酸杆菌和宋内志贺氏菌的操纵子进行了克隆，并通过物理图谱分析、Southern杂交和在小细胞中的蛋白质合成进行了表征。在宋内志贺氏菌中，与大肠杆菌K-12一样，frd和ampC操纵子重叠（T. Grundström和B. Jaurin，《美国国家科学院院刊》79:1111-1115，1982）。在整个frd-ampC区域仅发现两个操纵子之间有微小差异。在弗氏柠檬酸杆菌中，ampC和frd操纵子不重叠，被大约1100个碱基对隔开。推测弗氏柠檬酸杆菌染色体β-内酰胺酶的可诱导特性由这1100个碱基对的DNA片段编码。
