Datta D B, Krämer C, Henning U
J Bacteriol. 1976 Dec;128(3):834-41. doi: 10.1128/jb.128.3.834-841.1976.
Homogenotes, heterogenotes, and intergeneric hybrids have been studied that are diploid for the structural gene of a major outer cell envelope membrane protein (protein II) from Escherichia coli. This protein can act as a phage receptor. In wild-type homogenotes, diploidy for the gene did not cause a gene dosage effect. It could be shown with two heterogenotes that both the chromosomal mutant and the episomal wild-type genes are expressed, and in each case more of the mutant than the wild-type protein species was found in the cell envelope. In on case of 21 phage-resistant mutants missing protein II was a trans effect observed of the mutant gene on the expression of the episomal wild type gene. Transfer of E. coli episomes carrying the protein II structural gene into Salmonella typhimurium and Proteus mirabilis resulted in intergeneric hybrids that became sensitive to the relevant phage and harbored the E. coli protein II in their cell envelopes. The results may be taken as suggestive evidence for a simple feedback mechanism for the regulation of synthesis of protein II, and they show that there are no highly specific requirements on protein primary structure for incorporation into an outer cell envelope membrane.
对同源双倍体、异源双倍体和属间杂种进行了研究，它们对于来自大肠杆菌的一种主要外细胞膜蛋白（蛋白II）的结构基因而言是二倍体。这种蛋白可作为噬菌体受体。在野生型同源双倍体中，该基因的二倍体状态并未引起基因剂量效应。通过两个异源双倍体可以表明，染色体突变基因和附加体野生型基因均得到表达，并且在每种情况下，在细胞膜中发现的突变型蛋白比野生型蛋白更多。在21个缺失蛋白II的噬菌体抗性突变体中，观察到突变基因对附加体野生型基因表达的反式效应。将携带蛋白II结构基因的大肠杆菌附加体转移到鼠伤寒沙门氏菌和奇异变形杆菌中，产生了属间杂种，这些杂种对相关噬菌体变得敏感，并且在其细胞膜中含有大肠杆菌蛋白II。这些结果可被视为蛋白II合成调控的简单反馈机制的提示性证据，并且它们表明，对于整合到外细胞膜中，对蛋白质一级结构没有高度特异性要求。
