Karjalainen T K, Evans D G, So M, Lee C H
Department of Pathology, Indiana University School of Medicine, Indianapolis 46223.
Infect Immun. 1989 Apr;57(4):1126-30. doi: 10.1128/iai.57.4.1126-1130.1989.
The colonization factor antigen I (CFA/I) gene has been isolated and sequenced. The amino acid sequence of CFA/I deduced from the nucleotide sequence is composed of 170 amino acids. The first 23 amino acids are considered to be the signal peptide of the CFA/I protein since they are not present in the protein sequence. Among the remaining amino acids, only two are different from the protein sequence: amino acid position 76 is an aspartic acid instead of an asparagine, and position 97 is a serine instead of an alanine. The CFA/I gene has a typical Shine-Dalgarno sequence located 10 base pairs (bp) upstream from the initiation codon. The sequence TACAAT located 48 bp upstream from the initiation codon was tentatively designated the -10 sequence of the CFA/I gene promoter. No sequences homologous to the consensus -35 promoter sequence was found. A pair of inverted repeat sequences followed by a stretch of eight A's are located 45 bp downstream from the termination codon of the CFA/I gene; this region may be a rho-independent transcriptional terminator.
定居因子抗原I（CFA/I）基因已被分离并测序。从核苷酸序列推导的CFA/I氨基酸序列由170个氨基酸组成。前23个氨基酸被认为是CFA/I蛋白的信号肽，因为它们不存在于蛋白质序列中。在其余氨基酸中，只有两个与蛋白质序列不同：氨基酸位置76是天冬氨酸而非天冬酰胺，位置97是丝氨酸而非丙氨酸。CFA/I基因在起始密码子上游10个碱基对（bp）处有一个典型的Shine-Dalgarno序列。在起始密码子上游48 bp处的序列TACAAT被暂定命名为CFA/I基因启动子的-10序列。未发现与共有-35启动子序列同源的序列。一对反向重复序列后接一段8个A，位于CFA/I基因终止密码子下游45 bp处；该区域可能是一个不依赖ρ的转录终止子。
