Hsia R C, Bavoil P M
Department of Microbiology and Immunology, University of Rochester Medical Center, NY 14642, USA.
Gene. 1996 Oct 17;176(1-2):155-62. doi: 10.1016/0378-1119(96)00241-7.
The nucleotide sequence of a 3.1-kb genomic DNA fragment carrying the omp3, omp2 and srp gene homologs from Chlamydia psittaci strain GPIC was determined. A comparative analysis of the GPIC sequence with other chlamydial omp2-linked sequences reveals highly conserved omp3 and omp2 upstream sequences across species, suggesting a unified mechanism of transcription regulation. In contrast, the omp2-srp intergenic segment, which encompasses hypothetical srp transcriptional initiation sites, is relatively less conserved in length and in sequence. Examination of the predicted translation products reveals a high degree of homology within Omp3 and Omp2 across species, with the notable exception of the N-terminal fifth of Omp2. Although the latter segment displays relatively high interspecies sequence variation, it includes a smaller segment, whose high positive charge density is conserved across species, suggesting a conserved structure/function. In contrast to Omp2 and Omp3, a comparative analysis of the predicted amino acid (aa) sequence of the srp product reveals high homology within species, but relatively little across species. A 38-aa segment near the C-terminus of Srp, whose sequence is 64% identical between C. psittaci GPIC and C. trachomatis, is partially truncated in C. psittaci 6BC.
测定了来自鹦鹉热衣原体菌株GPIC的携带omp3、omp2和srp基因同源物的3.1kb基因组DNA片段的核苷酸序列。对GPIC序列与其他衣原体omp2连锁序列的比较分析揭示了跨物种高度保守的omp3和omp2上游序列，提示存在统一的转录调控机制。相比之下，包含假定的srp转录起始位点的omp2-srp基因间隔区在长度和序列上相对不那么保守。对预测的翻译产物的检查揭示了跨物种的Omp3和Omp2内具有高度同源性，但Omp2的N端五分之一除外。尽管后一段显示出相对较高的种间序列变异，但它包含一个较小的片段，其高正电荷密度在跨物种中是保守的，提示存在保守的结构/功能。与Omp2和Omp3不同，对srp产物预测的氨基酸(aa)序列的比较分析揭示了种内高度同源，但种间同源性相对较低。Srp C端附近的一个38个氨基酸的片段，其序列在鹦鹉热衣原体GPIC和沙眼衣原体之间有64%的同一性，在鹦鹉热衣原体6BC中部分截短。
