National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Science, 300 Fenglin Road, Shanghai 200032, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Rep. 2016 Jun 22;6:28361. doi: 10.1038/srep28361.
The cyanobacterial NAD(P)H dehydrogenase (NDH-1) complexes play crucial roles in variety of bioenergetic reactions. However, the regulative mechanism of NDH-1 under stressed conditions is still unclear. In this study, we detected that the NDH-1 activity is partially impaired, but the accumulation of NDH-1 complexes was little affected in the NdhV deleted mutant (ΔndhV) at low light in cyanobacterium Synechocystis sp. PCC 6803. ΔndhV grew normally at low light but slowly at high light under inorganic carbon limitation conditions (low pH or low CO2), meanwhile the activity of CO2 uptake was evidently lowered than wild type even at pH 8.0. The accumulation of NdhV in thylakoids strictly relies on the presence of the hydrophilic subcomplex of NDH-1. Furthermore, NdhV was co-located with hydrophilic subunits of NDH-1 loosely associated with the NDH-1L, NDH-1MS' and NDH-1M complexes. The level of the NdhV was significantly increased at high light and deletion of NdhV suppressed the up-regulation of NDH-1 activity, causing the lowered the photosynthetic oxygen evolution at pH 6.5 and high light. These data indicate that NdhV is an intrinsic subunit of hydrophilic subcomplex of NDH-1, required for efficient operation of cyclic electron transport around photosystem I and CO2 uptake at high lights.
蓝细菌 NAD(P)H 脱氢酶 (NDH-1) 复合物在多种生物能量反应中发挥着关键作用。然而，NDH-1 在胁迫条件下的调节机制尚不清楚。在这项研究中，我们发现 NDH-1 活性部分受损，但在 Synechocystis sp. PCC 6803 的 NdhV 缺失突变体（ΔndhV）中，NDH-1 复合物的积累在低光照下几乎不受影响。ΔndhV 在低光照下正常生长，但在无机碳限制条件（低 pH 或低 CO2）下的高光下生长缓慢，同时 CO2 摄取活性明显低于野生型，即使在 pH 8.0 下也是如此。NdhV 在类囊体中的积累严格依赖于 NDH-1 的亲水亚基复合物的存在。此外，NdhV 与 NDH-1L、NDH-1MS' 和 NDH-1M 复合物松散结合的亲水亚基的 NDH-1 一起共定位。在高光下，NdhV 的水平显著增加，而 NdhV 的缺失抑制了 NDH-1 活性的上调，导致在 pH 6.5 和高光下光合作用氧气释放降低。这些数据表明，NdhV 是 NDH-1 亲水亚基复合物的内在亚基，是在高光下高效运行围绕光系统 I 的循环电子传递和 CO2 摄取所必需的。
