Sub-cellular location of FtsH proteases in the cyanobacterium Synechocystis sp. PCC 6803 suggests localised PSII repair zones in the thylakoid membranes.
Sub-cellular location of FtsH proteases in the cyanobacterium Synechocystis sp. PCC 6803 suggests localised PSII repair zones in the thylakoid membranes.
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DOI：
10.1111/mmi.12940
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发表时间：
2015-05
影响因子：
3.6
通讯作者：
Mullineaux CW
中科院分区：
文献类型：
--
作者：
Sacharz J;Bryan SJ;Yu J;Burroughs NJ;Spence EM;Nixon PJ;Mullineaux CW
在蓝细菌和叶绿体中，暴露于HL会损害光合机构，特别是光系统II的D1亚基。为了避免慢性光抑制，PSII修复周期的运作，以取代受损的PSII亚基与新合成的版本。为了确定这一过程的亚细胞位置，我们研究了FtsH金属蛋白酶的定位，其中一些直接参与降解受损的D1。我们产生了蓝细菌S ynechocystis sp. PCC 6803的转化体，其表达其四种FtsH蛋白酶的GFP标记版本。在我们的条件下，ftsH 2-gfp菌株对PSII修复有功能。共聚焦显微镜显示，FtsH 1主要是在细胞质膜，而其余的FtsH蛋白的补丁无论是在类囊体或类囊体和细胞质膜之间的界面。HL曝光，增加了光系统II修复周期的活性导致FtsH分布没有检测到的变化，与FtsH 2蛋白酶参与D1降解保留其斑片状分布在类囊体膜。我们讨论的可能性，FtsH 2-GFP补丁代表光系统II的“修复区”内的类囊体膜，和可能的优势，这种功能专门的膜区。抗GFP亲和力唐斯提供了推定修复区组成的第一个指示。
In cyanobacteria and chloroplasts, exposure to HL damages the photosynthetic apparatus, especially the D1 subunit of Photosystem II. To avoid chronic photoinhibition, a PSII repair cycle operates to replace damaged PSII subunits with newly synthesised versions. To determine the sub‐cellular location of this process, we examined the localisation of FtsH metalloproteases, some of which are directly involved in degrading damaged D1. We generated transformants of the cyanobacterium S ynechocystis sp. PCC6803 expressing GFP‐tagged versions of its four FtsH proteases. The ftsH2–gfp strain was functional for PSII repair under our conditions. Confocal microscopy shows that FtsH1 is mainly in the cytoplasmic membrane, while the remaining FtsH proteins are in patches either in the thylakoid or at the interface between the thylakoid and cytoplasmic membranes. HL exposure which increases the activity of the Photosystem II repair cycle led to no detectable changes in FtsH distribution, with the FtsH2 protease involved in D1 degradation retaining its patchy distribution in the thylakoid membrane. We discuss the possibility that the FtsH2–GFP patches represent Photosystem II ‘repair zones’ within the thylakoid membranes, and the possible advantages of such functionally specialised membrane zones. Anti‐GFP affinity pull‐downs provide the first indication of the composition of the putative repair zones.