Inactivation of the open reading frame slr0399 in Synechocystis sp PCC 6803 functionally complements mutations near the QA niche of photosystem II -: A possible role of slr0399 as a chaperone for quinone binding
Inactivation of the open reading frame slr0399 in Synechocystis sp PCC 6803 functionally complements mutations near the QA niche of photosystem II -: A possible role of slr0399 as a chaperone for quinone binding
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DOI：
10.1074/jbc.274.43.30540
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发表时间：
1999-10-22
影响因子：
4.8
通讯作者：
Vermaas, W
中科院分区：
文献类型：
--
作者：
Ermakova-Gerdes, S;Vermaas, W
在光系统II的D2亚基中具有V247 M/A249 T/M329 I突变的集胞藻PCC 6803三重突变体D2 R8的Q（A）功能受损，具有明显移动的Q（A），并且不能光自养生长。已分离出该突变体的几个光合自养假回复突变体，其中每一个都保留了D2 R8的原始psbDI突变。使用新开发的作图技术，已将次级突变的位点定位在开放阅读框slr 0399中。两种不同的核苷酸取代和约60%的slr 0399的缺失分别显示恢复在不同的假回复突变体D2 R8的光合自养，这表明失活的Slr 0399导致在D2 R8的光合自养生长。事实上，slr 0399的靶向缺失恢复了D2 R8和QA功能受损的其他psbDI突变体中的光自养。Slr 0399与假设的蛋白质Ycf 39相似，Ycf 39编码于蓝藻（Cyanophora paradoxa）的蓝色素基因组中;硅藻、甲藻和红藻的叶绿体基因组中;以及拟南芥的核基因组中。Slr 0399和Ycf 39在其N末端附近具有NAD（P）H结合基序，并且与NAD还原酶样蛋白和真核生物NADH脱氢酶复合物I的亚基具有一些相似性。野生型集胞藻PCC 6803中slr 0399的缺失除了在光自养和光混合营养条件下的耐热性降低之外没有显著的表型效应。我们认为，SLR 0399是一个伴侣样蛋白，艾滋病，但不是必不可少的，醌插入和蛋白质折叠周围的Q（A）在光系统II。此外，由于Slr 0399的作用不限于光系统II，因此该蛋白质也可能参与其他光合和呼吸复合物中醌的组装。
The Synechocystis sp. PCC 6803 triple mutant D2R8 with V247M/A249T/M329I mutations in the D2 subunit of the photosystem II is impaired in Q(A) function, has an apparently mobile Q(A), and is unable to grow photoautotrophically. Several photoautotrophic pseudorevertants of this mutant have been isolated, each of which retained the original psbDI mutations of D2R8 Using a newly developed mapping technique, the site of the secondary mutations has been located in the open reading frame slr0399. Two different nucleotide substitutions and a deletion of about 60% of slr0399 were each shown to restore photoautotrophy in different pseudorevertants of the mutant D2R8, suggesting that inactivation of Slr0399 leads to photoautotrophic growth in D2R8. Indeed, a targeted deletion of slr0399 restores photoautotrophy in D2R8 and in other psbDI mutants impaired in QA function. Slr0399 is similar to the hypothetical protein Ycf39, which is encoded in the cyanelle genome of Cyanophora paradoxa; in the chloroplast genomes of diatoms, dinoflagellates, and red algae; and in the nuclear genome of Arabidopsis thaliana. Slr0399 and Ycf39 have a NAD(P)H binding motif near their N terminus and have some similarity to isoflavone reductase-like proteins and to a subunit of the eukaryotic NADH dehydrogenase complex I. Deletion of slr0399 in wild type Synechocystis sp. PCC 6803 has no significant phenotypic effects other than a decrease in thermotolerance under both photoautotrophic and photomixotrophic conditions. We suggest that Slr0399 is a chaperone-like protein that aids in, but is not essential for, quinone insertion and protein folding around Q(A) in photosystem II. Moreover, as the effects of Slr0399 are not limited to photosystem II, this protein may also be involved in assembly of quinones in other photosynthetic and respiratory complexes.