To K Y, Lai E M, Lee L Y, Lin T P, Hung C H, Chen C L, Chang Y S, Liu S T
Department of Microbiology and Immunology, Chang-Gung Medical College, Kwei-Shan, Taoyuan, Taiwan.
Microbiology (Reading). 1994 Feb;140 ( Pt 2):331-9. doi: 10.1099/13500872-140-2-331.
Erwinia herbicola is known to synthesize carotenoids and gives an orange-coloured phenotype. These carotenoids play a role in the protection of the cells from the damage caused by near-UV irradiation in nature. The genes encoding these carotenoids in E. herbicola Eho13 are clustered in a 7 kb DNA fragment. The complete sequence of this fragment has been determined. DNA sequence analysis revealed that the entire sequence contains at least five genes, which are transcribed in the same direction. These five genes are organized in the order crtE-crtX-crtY-crtI-crtB. A gene fusion study showed that two different regions in this 7 kb gene cluster contain promoter activity. Primer-extension analysis identified two transcription start sites, located 147 bp upstream from the first gene of the cluster, crtE, and within the last gene of the cluster, crtB. An RNA-PCR study suggested that the five crt genes were organized in an operon and were transcribed from the promoter upstream from crtE.
已知草生欧文氏菌能合成类胡萝卜素并呈现橙色表型。这些类胡萝卜素在自然界中起到保护细胞免受近紫外线辐射损伤的作用。草生欧文氏菌Eho13中编码这些类胡萝卜素的基因聚集在一个7 kb的DNA片段中。该片段的完整序列已被测定。DNA序列分析表明，整个序列至少包含五个基因，它们沿相同方向转录。这五个基因按crtE - crtX - crtY - crtI - crtB的顺序排列。一项基因融合研究表明，这个7 kb基因簇中的两个不同区域具有启动子活性。引物延伸分析确定了两个转录起始位点，分别位于该基因簇的第一个基因crtE上游147 bp处以及该基因簇的最后一个基因crtB内部。一项RNA - PCR研究表明，这五个crt基因组成一个操纵子，并从crtE上游的启动子转录。
