Göransson M, Forsman K, Uhlin B E
Department of Microbiology, University of Umeã, Sweden.
Mol Gen Genet. 1988 Jun;212(3):412-7. doi: 10.1007/BF00330844.
Expression of the digalactoside-binding Pap pili involves two trans-acting regulatory genes, papB and papI. Using pap-lac operon fusions and DNA hybridization probes derived from pap DNA we tested whether or not other pili-adhesin determinants from different Escherichia coli strains encode homologs to the pap regulatory genes. Digalactoside-specific clones of serotypes F72 and F11 complemented papB and papI mutants of the Pap (serotype F13) clone and DNA hybridization analysis showed that the clones are homologous in the DNA sequences encoding the two regulatory genes. Similar results were obtained with an S-pili determinant which mediates binding to sialic acid-containing receptors and the findings suggest that the regulatory regions may be more conserved than other genes in different pili-adhesin gene clusters. Determinants for type 1-pili (mannose-specific binding) and for pili associated with enterotoxigenic E. coli (K88, K99, CFAI, CFAII) did not appear to contain DNA sequences homologous to papB or papI. E. coli strain J96, which was the origin of the pap DNA, was found to carry two additional copies of papB-papI homologous sequences in the chromosome. In strains expressing more than one kind of pili the trans-active gene products thereby may allow for regulatory interaction between separate pili-adhesin gene systems.
双半乳糖苷结合性Pap菌毛的表达涉及两个反式作用调节基因，papB和papI。我们利用pap - lac操纵子融合体以及源自pap DNA的DNA杂交探针，来检测不同大肠杆菌菌株的其他菌毛黏附素决定簇是否编码与pap调节基因同源的基因。F72和F11血清型的双半乳糖苷特异性克隆对Pap（F13血清型）克隆的papB和papI突变体起到了互补作用，并且DNA杂交分析表明，这些克隆在编码这两个调节基因的DNA序列上是同源的。对于介导与含唾液酸受体结合的S菌毛决定簇，也得到了类似结果，这些发现表明，在不同的菌毛黏附素基因簇中，调节区域可能比其他基因更为保守。1型菌毛（甘露糖特异性结合）以及与产肠毒素大肠杆菌相关的菌毛（K88、K99、CFAI、CFAII）的决定簇似乎不包含与papB或papI同源的DNA序列。发现作为pap DNA来源的大肠杆菌菌株J96在染色体中还携带另外两个papB - papI同源序列拷贝。在表达不止一种菌毛的菌株中，反式作用基因产物因此可能允许不同菌毛黏附素基因系统之间进行调节相互作用。
