Mimuro Mamoru, Tomo Tatsuya, Tsuchiya Tohru
Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan.
Photosynth Res. 2008 Aug;97(2):167-76. doi: 10.1007/s11120-008-9311-4. Epub 2008 Jun 21.
The evolutionary route from anoxygenic photosynthetic bacteria to oxygenic cyanobacteria is discontinuous in terms of photochemical/photophysical reaction systems. It is difficult to describe this transition process simply because there are no recognized intermediary organisms between the two bacterial groups. Gloeobacter violaceus PCC 7421 might be a model organism that is suitable for analysis because it still possesses primordial characteristics such as the absence of thylakoid membranes. Whole genome analysis and biochemical and biophysical surveys of G. violaceus have favored the hypothesis that it is an intermediary organism. On the other hand, species differentiation is an evolutionary process that could be driven by changes in a small number of genes, and this process might give fair information more in details by monitoring of those genes. Comparative studies of genes, including those in Acaryochloris marina MBIC 11017, have provided information relevant to species differentiation; in particular, the acquisition of a new pigment, chlorophyll d, and changes in amino acid sequences have been informative. Here, based on experimental evidence from these two species, we discuss some of the evolutionary pathways for the appearance and differentiation of cyanobacteria.
就光化学/光物理反应系统而言，从无氧光合细菌到产氧蓝细菌的进化路线是不连续的。由于这两类细菌之间不存在公认的中间生物，因此很难简单描述这一过渡过程。紫球藻PCC 7421可能是一种适合进行分析的模式生物，因为它仍然具有一些原始特征，比如没有类囊体膜。对紫球藻进行的全基因组分析以及生化和生物物理研究都支持了它是中间生物这一假说。另一方面，物种分化是一个可能由少数基因变化驱动的进化过程，通过监测这些基因，这一过程可能会提供更详细准确的信息。对包括滨海栖热放线菌MBIC 11017在内的基因进行的比较研究，提供了与物种分化相关的信息；特别是，新色素叶绿素d的获得以及氨基酸序列的变化都很有参考价值。在此，基于来自这两个物种的实验证据，我们讨论了蓝细菌出现和分化的一些进化途径。
