Dynamic Interplay between Nucleoid Segregation and Genome Integrity in Chlamydomonas Chloroplasts
Dynamic Interplay between Nucleoid Segregation and Genome Integrity in Chlamydomonas Chloroplasts
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DOI：
10.1104/pp.16.01533
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发表时间：
2016-12-01
期刊：
影响因子：
7.4
通讯作者：
Nishimura, Yoshiki
中科院分区：
文献类型：
--
作者：
Odahara, Masaki;Kobayashi, Yusuke;Nishimura, Yoshiki
叶绿体（cp）基因组被组织成分散在整个cp基质中的类核。以前，细菌重组酶RecA（cpRECA）的cp同源物被证明是参与维护cp基因组的完整性，修复受损的叶绿体DNA和抑制异常重组之间的短分散重复的藓小立碗藓。在这里，cpRECA在绿色衣藻莱茵衣藻中的过表达和敲低分析揭示，cpRECA参与cp类核动力学以及在维持cp基因组完整性方面具有作用。标记有黄色荧光蛋白或血凝素的cpRECA的过表达导致形成的巨大的丝状结构，共定位专门叶绿体DNA和cpRECA本地化CP类核在一个异质性的方式。敲低cpRECA导致cp类核数目显著减少，并伴有类核增大。这种表型类似于旋转酶底物处理的细胞和单核叶绿体突变体细胞，并建议cpRECA参与组织CP类核动力学。cp基因组也不稳定的诱导重组cpRECA敲低细胞和促旋酶激活剂处理的细胞之间的短分散重复序列。综上所述，这些结果表明，cpRECA和促旋酶都参与了类核动力学和基因组完整性的维持，这些过程的机制可能与C。莱茵哈迪角
The chloroplast (cp) genome is organized as nucleoids that are dispersed throughout the cp stroma. Previously, a cp homolog of bacterial recombinase RecA (cpRECA) was shown to be involved in the maintenance of cp genome integrity by repairing damaged chloroplast DNA and by suppressing aberrant recombination between short dispersed repeats in the moss Physcomitrella patens. Here, overexpression and knockdown analysis of cpRECA in the green alga Chlamydomonas reinhardtii revealed that cpRECA was involved in cp nucleoid dynamics as well as having a role in maintaining cp genome integrity. Overexpression of cpRECA tagged with yellow fluorescent protein or hemagglutinin resulted in the formation of giant filamentous structures that colocalized exclusively to chloroplast DNA and cpRECA localized to cp nucleoids in a heterogenous manner. Knockdown of cpRECA led to a significant reduction in cp nucleoid number that was accompanied by nucleoid enlargement. This phenotype resembled those of gyrase inhibitor-treated cells and monokaryotic chloroplast mutant cells and suggested that cpRECA was involved in organizing cp nucleoid dynamics. The cp genome also was destabilized by induced recombination between short dispersed repeats in cpRECA-knockdown cells and gyrase inhibitor-treated cells. Taken together, these results suggest that cpRECA and gyrase are both involved in nucleoid dynamics and the maintenance of genome integrity and that the mechanisms underlying these processes may be intimately related in C. reinhardtii cps.