Duggan P S, Parker S D, Phillips-Jones M K
Division of Microbiology, School of Biochemistry and Molecular Biology, University of Leeds, Leeds LS2 9JT, UK.
FEMS Microbiol Lett. 2000 Aug 15;189(2):239-46. doi: 10.1111/j.1574-6968.2000.tb09237.x.
Analysis of the photoactive yellow protein (pyp) gene region of Rhodobacter sphaeroides has revealed the presence of an additional open reading frame, orfD, that had not previously been identified. Here we report the location of this new gene and the predicted amino acid sequence of the encoded protein. The translation product resembles a group of small cytochrome b-like proteins, including Escherichia coli cytochrome b(561), R. sphaeroides cytochrome b(562), and two new cytochrome b(561)-like proteins identified using the E. coli genome sequence, for which functions have not yet been established. To determine OrfD function in R. sphaeroides, an orfD mutant was constructed. The OrfD mutant exhibited growth rates and yields very similar to those of the wild-type strain when grown under a variety of growth conditions. Respiration rates, reduced-minus-oxidised spectra and levels of photosynthetic complexes were also very similar in the two strains. Although the role of OrfD was therefore not determined here, we demonstrate that the orfD gene is expressed in R. sphaeroides under aerobic, semi-aerobic and photosynthetic growth conditions.
对球形红细菌光活性黄色蛋白（PYP）基因区域的分析揭示了一个此前未被识别的额外开放阅读框orfD的存在。在此，我们报告这个新基因的位置以及所编码蛋白质的预测氨基酸序列。该翻译产物类似于一组小的细胞色素b样蛋白，包括大肠杆菌细胞色素b（561）、球形红细菌细胞色素b（562），以及利用大肠杆菌基因组序列鉴定出的两种新的细胞色素b（561）样蛋白，其功能尚未确定。为了确定球形红细菌中OrfD的功能，构建了一个orfD突变体。在多种生长条件下培养时，OrfD突变体的生长速率和产量与野生型菌株非常相似。两种菌株的呼吸速率、还原态减去氧化态光谱以及光合复合物水平也非常相似。因此，尽管此处尚未确定OrfD的作用，但我们证明orfD基因在球形红细菌的需氧、半需氧和光合生长条件下均有表达。
