Three PsbQ-like proteins are required for the function of the chloroplast NAD(P)H dehydrogenase complex in Arabidopsis.
Three PsbQ-like proteins are required for the function of the chloroplast NAD(P)H dehydrogenase complex in Arabidopsis.
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DOI：
10.1093/pcp/pcq060
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发表时间：
2010-06
影响因子：
4.9
通讯作者：
Shinya Yabuta;K. Ifuku;Atsushi Takabayashi;Seiko Ishihara;K. Ido;Noriko Ishikawa;T. Endo;F. Sato-
中科院分区：
文献类型：
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作者：
Shinya Yabuta;K. Ifuku;Atsushi Takabayashi;Seiko Ishihara;K. Ido;Noriko Ishikawa;T. Endo;F. Sato-
拟南芥除了PSII放氧复合物的PsbQ亚基外，还具有三种PsbQ样（PQL）蛋白。最近的生物信息学和蛋白质组学研究表明，两个PQL蛋白，PQL 1（At 1g 14150）和PQL 2（At 3g 01440），可能在叶绿体NAD（P）H脱氢酶（NDH）复合体中发挥作用，但其分子功能尚未得到表征。在这项研究中，我们研究了拟南芥pql 1和pql 2突变体中叶绿体NDH的功能。光照后增加叶绿素荧光，这是由NDH依赖的循环电子流，是不存在的两个突变体，表明PQL 1和PQL 2所需的NDH活性。在野生型植物的类囊体膜中，PQL 1和PQL 2与NDH-PSI超复合物紧密相关，并受到蛋白酶处理的保护，而未组装的PQL在缺乏已知NDH亚基的突变体中不稳定积累。NDH复合物的亚基稳定性在pql 1和pql 2突变体的类囊体膜中受到不同的影响。这些数据表明，PQL 1和PQL 2是新的NDH亚基和不同的功能作用，在NDH复合物中的结合位点。此外，使用pql 3突变体对PQL 3（At 2g 01918）的功能分析表明，PQL 3也是NDH活性所需的。与每个PQL蛋白同源的蛋白质存在于各种植物物种中，但不在蓝细菌、藻类、苔藓或蕨类中。这些结果表明，在叶绿体中具有NDH活性的种子植物特异性地开发了三种PQL蛋白用于叶绿体NDH复合物的功能。
Arabidopsis has three PsbQ-like (PQL) proteins in addition to the PsbQ subunit of the oxygen-evolving complex of PSII. Recent bioinformatic and proteomic studies suggested that the two PQL proteins, PQL1 (At1g14150) and PQL2 (At3g01440), might function in the chloroplast NAD(P)H dehydrogenase (NDH) complex; however, their molecular function has not been characterized. In this study, we examined the function of the chloroplast NDH in the Arabidopsis pql1 and pql2 mutants. Post-illumination increases in Chl fluorescence, which are caused by an NDH-dependent cyclic electron flow, were absent in both mutants, indicating that PQL1 and PQL2 are required for NDH activity. In the thylakoid membranes of wild-type plants, PQL1 and PQL2 were tightly associated with the NDH-PSI supercomplex and protected from protease treatments, while unassembled PQLs were not stably accumulated in mutants lacking known NDH subunits. Subunit stability of the NDH complex was affected differently in the thylakoid membranes of the pql1 and pql2 mutants. These data indicate that PQL1 and PQL2 are novel NDH subunits and differ in their functional roles and in their binding sites in the NDH complex. Furthermore, functional analysis on PQL3 (At2g01918) using the pql3 mutant suggests that PQL3 is also required for NDH activity. Proteins homologous to each PQL protein are found in various plant species, but not in cyanobacteria, algae, mosses or ferns. These results suggest that seed plants that have NDH activity in chloroplasts specifically developed three PQL proteins for the function of the chloroplast NDH complex.