Analysis of spontaneous suppressor mutants from the photomixotrophically-grown pmgA-disrupted mutant in the cyanobacterium Synechocystis sp. PCC 6803
Analysis of spontaneous suppressor mutants from the photomixotrophically-grown pmgA-disrupted mutant in the cyanobacterium Synechocystis sp. PCC 6803
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对蓝藻集胞藻中光合营养生长的 pmgA 破坏突变体的自发抑制突变体进行分析。
DOI：
10.1007/s11120-015-0143-8
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Y.
中科院分区：
文献类型：
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作者：
Nishijima;Y.;Kanesaki;Y.;Yoshikawa;H.;Ogawa;T.;Sonoike;K.;Nishiyama;Y. and Hihara;Y.
蓝藻集胞藻（Synechocystissp.）PCC 6803在光混合营养条件下遭受严重的生长抑制。为了阐明使细胞能够在光混合营养条件下生长的关键因素，我们从来自单个菌落的Δ pmgA突变体中分离出自发抑制突变体。将Δ pmgA突变体涂布在加葡萄糖的BG 11琼脂平板上，背景细胞漂白后出现抑制突变体菌落。我们鉴定了这些抑制突变体的突变位点，发现13个突变体中有11个突变与1型NAD（P）H脱氢酶（NDH-1）复合物相关。其中8个突变体在hF3（sll 1732）基因内发生突变：R32stop、W62stop、V147I、G266V、G354W、G586C，编码区缺失7bp。一个突变体在thendhC（slr1279）基因的假定的-10盒中插入一个碱基，导致thendhCK操纵子的转录减少。两个突变体cupA（sll 1734）编码区有一个碱基的插入和缺失，cupA与ndhF3和ndhD3共转录，共同构成一种参与诱导型高亲和力CO2摄取的NDH-1复合物（NDH-1MS复合物）。结果表明，在1%CO2的光混合营养条件下，该复合物活性的丧失有效地拯救了Δ pmgA突变体。然而，在归因于NDH-1MS复合物的活性方面，观察到WT和突变体之间几乎没有差异，即，CO2吸收和循环电子传递。这可能表明NDH-1MS复合物在光混合营养条件下具有第三种目前未知的功能。
ThepmgA-disrupted (ΔpmgA) mutant in the cyanobacteriumSynechocystissp. PCC 6803 suffers severe growth inhibition under photomixotrophic conditions. In order to elucidate the key factors enabling the cells to grow under photomixotrophic conditions, we isolated spontaneous suppressor mutants from the ΔpmgAmutant derived from a single colony. When the ΔpmgAmutant was spread on a BG11 agar plate supplemented with glucose, colonies of suppressor mutants appeared after the bleaching of the background cells. We identified the mutation site of these suppressor mutants and found that 11 mutants out of 13 had a mutation in genes related to the type 1 NAD(P)H dehydrogenase (NDH-1) complex. Among them, eight mutants had mutations within thendhF3(sll1732) gene: R32stop, W62stop, V147I, G266V, G354W, G586C, and deletion of 7 bp within the coding region. One mutant had one base insertion in the putative −10 box of thendhC(slr1279) gene, leading to the decrease in the transcripts of thendhCKJoperon. Two mutants had one base insertion and deletion in the coding region ofcupA(sll1734), which is co-transcribed withndhF3andndhD3and comprises together a form of NDH-1 complex (NDH-1MS complex) involved in inducible high-affinity CO2uptake. The results indicate that the loss of the activity of this complex effectively rescues the ΔpmgAmutant under photomixotrophic condition with 1 % CO2. However, little difference among WT and mutants was observed in the activities ascribed to the NDH-1MS complex, i.e., CO2uptake and cyclic electron transport. This may suggest that the NDH-1MS complex has the third, currently unknown function under photomixotrophic conditions.