Higgs D C, Kuras R, Kindle K L, Wollman F A, Stern D B
Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, New York, USA.
Plant J. 1998 Jun;14(6):663-71. doi: 10.1046/j.1365-313x.1998.00165.x.
FUD6 is a non-photosynthetic Chlamydomonas mutant that lacks the cytochrome b6/f complex, due to a 236 bp deletion that removes the promoter and part of the 5' untranslated region (UTR) of the chloroplast petD gene, which encodes subunit IV of the complex. Two photosynthetic revertants of FUD6 that synthesized wild-type levels of subunit IV were found to contain related inversions of the chloroplast genome that resulted from recombination between small inverted repeats. These inversions created a functional chimeric petD gene that includes the promoter and part of the 5' UTR of the newly identified ycf9-psbM transciption unit, fused to the petD 5' UTR upstream of the FUD6 deletion. Accumulation of the ycf9-psbM dicistronic transcript was disrupted in the revertants, but monocistronic psbM mRNA accumulated normally. The FUD6 revertants demonstrate the ability of the Chlamydomonas chloroplast genome to undergo a large inversion without a deleterious effect on chloroplast function, reminiscent of events that have led to the evolutionary divergence of chloroplast genomes.
FUD6是一种非光合衣藻突变体，由于236 bp的缺失，它缺少细胞色素b6/f复合体，该缺失移除了叶绿体petD基因的启动子和部分5'非翻译区（UTR），petD基因编码该复合体的亚基IV。发现两个合成野生型水平亚基IV的FUD6光合回复突变体含有叶绿体基因组的相关倒位，这些倒位是由小反向重复序列之间的重组产生的。这些倒位产生了一个功能性嵌合petD基因，该基因包括新鉴定的ycf9-psbM转录单元的启动子和部分5'UTR，与FUD6缺失上游的petD 5'UTR融合。ycf9-psbM双顺反子转录本的积累在回复突变体中被破坏，但单顺反子psbM mRNA正常积累。FUD6回复突变体证明了衣藻叶绿体基因组进行大倒位而对叶绿体功能没有有害影响的能力，这让人想起导致叶绿体基因组进化分歧的事件。
