Wu Q, Yu J, Zhao N
Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing, PR China.
IUBMB Life. 2001 May;51(5):289-93. doi: 10.1080/152165401317190789.
A chlL-deletion mutant of Synechocystis sp. PCC 6803 designated as chlL- was unable to make significant amounts of chlorophyll in darkness. However, an apparent pseudorevertant has been generated spontaneously that can synthesize an increased amount of chlorophyll under light-activated heterotrophic growth conditions. Under these conditions, the chlorophyll content in this pseudorevertant was about 20% of that in the wild-type strain and about 4 times more than that in the original and in the recently recreated chlL-deletion mutant. This is paralleled by increased performance of dark-grown cells in terms of chlorophyll fluorescence induction and oxygen evolution rates in the pseudorevertant versus in the original mutant. PCR analysis confirmed that the chlL- -pseudorevertant mutant still lacked the chlL gene. These results imply that the light-independent chlorophyll biosynthesis pathway was partly recovered.
集胞藻6803的一个chlL缺失突变体，命名为chlL-，在黑暗中无法合成大量叶绿素。然而，自发产生了一个明显的假回复突变体，在光激活异养生长条件下，它能合成更多的叶绿素。在这些条件下，该假回复突变体中的叶绿素含量约为野生型菌株的20%，是原始chlL缺失突变体及最近重建的chlL缺失突变体的约4倍。与此平行的是，在叶绿素荧光诱导和放氧速率方面，与原始突变体相比，黑暗生长的假回复突变体细胞的性能有所提高。PCR分析证实，chlL-假回复突变体仍然缺乏chlL基因。这些结果表明，不依赖光的叶绿素生物合成途径得到了部分恢复。
