Mäkelä P H, Schmidt G, Mayer H, Nikaido H, Whang H Y, Neter E
J Bacteriol. 1976 Sep;127(3):1141-9. doi: 10.1128/jb.127.3.1141-1149.1976.
The his-rfb deletion series of Salmonella typhimurium mutants characterized previously by Nikaido et al. was examined for the presence of the enterobacterial common antigen (ECA). All deletions not extending further to the left than the genes for cytidine phosphoabequose synthesis were ECA positive, whereas longer deletions (extending to the genes for thymidine diphosphorhamnose synthesis or further) were ECA negative. When these long-his-rfb deletion strains were studied further, it became clear that they (four out of four studied) had accumulated a second mutation, called rff, close to ilv, which prevented the synthesis of ECA. When rff- was replaced by rff+, the recombinants, now having the his-rfb deletion only, produced traces of ECA, showed reduced viability, increased sensitivity to sodium dodecyl sulfate (SDS) and to a lesser extent, to other anionic detergents, and accumulated secondary "suppressor" mutations upon storage. Such suppressor-containing mutants could be isolated by selecting for resistance to 1% SDS. Thirty of 46 SDS-resistant mutants studied had a second mutation, which alone prevented the synthesis of ECA, close to ilv. This ilv-linked mutation was similar to the rff mutation of the strains studied originally. The new rff mutation was similar to previously described rfe mutations in its close linkage to ilv and association with an ECA-negative phenotype. It differed from rfe, however, by not affecting the synthesis of the O antigens (O-6,7) of group C1. In Salmonella group C1, all ECA genes identified thus far are linked to ilv (rfe and/or rff) and none is linked to rfb.
对先前由尼凯多等人鉴定的鼠伤寒沙门氏菌his-rfb缺失系列突变体进行了肠杆菌共同抗原（ECA）检测。所有向左延伸不超过胞苷磷酸阿比可糖合成基因的缺失突变体都是ECA阳性，而更长的缺失突变体（延伸至胸苷二磷酸鼠李糖合成基因或更远）则是ECA阴性。当对这些长his-rfb缺失菌株进行进一步研究时，发现它们（所研究的四个菌株全部如此）积累了第二个突变，称为rff，靠近ilv基因，该突变阻止了ECA的合成。当rff-被rff+取代时，重组体现在仅具有his-rfb缺失，产生微量ECA，活力降低，对十二烷基硫酸钠（SDS）的敏感性增加，对其他阴离子洗涤剂的敏感性在较小程度上也增加，并且在储存时积累了二级“抑制”突变。通过选择对1% SDS的抗性可以分离出这种含有抑制子的突变体。在所研究的46个SDS抗性突变体中，有30个具有第二个突变，该突变单独阻止了ECA的合成，靠近ilv基因。这种与ilv连锁的突变类似于最初研究的菌株中的rff突变。新的rff突变在与ilv的紧密连锁以及与ECA阴性表型的关联方面与先前描述的rfe突变相似。然而，它与rfe的不同之处在于不影响C1群O抗原（O-6,7）的合成。在沙门氏菌C1群中，迄今为止鉴定的所有ECA基因都与ilv（rfe和/或rff）连锁，没有一个与rfb连锁。
