Localization of the small CAB-like proteins in photosystem II
Localization of the small CAB-like proteins in photosystem II
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DOI：
10.1074/jbc.m605463200
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发表时间：
2007-01-05
影响因子：
4.8
通讯作者：
Funk, Christiane
中科院分区：
文献类型：
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作者：
Yao, Danny;Kieselbach, Thomas;Funk, Christiane
蓝藻小CAB样蛋白(SCP)由一个类似于植物捕光蛋白跨膜区的单螺旋蛋白组成。为了确定这些蛋白质是否与类囊体膜上的蛋白质复合体相关，用His标签标记了SCP家族中丰富的成员SCPD，并鉴定了与His标记的SCPD共分离的蛋白质。这些蛋白质包括光系统(PS)II的主要成分以及参与PSII复合体降解的FtsH。为了确定SCPD和PSII复合体之间的特异性相互作用，对His标记的蛋白质组分进行了双向Blue Native/SDS-PAGE。同样，PSII组分与SCPD-His共分离，SCPD-His被发现与CP47相互作用最强。SCPD结合以PSII的单体形式最为突出，提示SCPD与PSII的联系已修复。使用识别SCPC和SCPD的抗体，我们发现在一级结构上与SCPD非常相似的SCPC蛋白也与PSII复合体共分离。相反，SCPE没有与类囊体中的一个主要蛋白质复合体共分离。SCP家族的第四个成员SCPB不能被免疫检测，但通过质谱仪在与SCPD-His共分离的样本中发现。因此，SCPB可能也与SCPD有关。SCP和PSI之间没有关联。基于这些和其他数据，我们认为SCP家族的成员可以与受损的PSII联系在一起，并在PSII组件被替换时作为临时的色素储存库。
The cyanobacterial small CAB-like proteins (SCPs) consist of one-helix proteins that resemble transmembrane regions of the light-harvesting proteins of plants. To determine whether these proteins are associated with protein complexes in the thylakoid membrane, an abundant member of the SCP family, ScpD, was marked with a His tag, and proteins co-isolating with His-tagged ScpD were identified. These proteins included the major Photosystem (PS) II components as well as FtsH, which is involved in degradation of the PSII complex. To ascertain specific interaction between ScpD and the PSII complex, the His-tagged protein fraction was subjected to two-dimensional blue native/SDS-PAGE. Again, PSII components were co-isolated with ScpD-His, and ScpD-His was found to interact most strongly with CP47. ScpD association was most prominent with the monomeric form of PSII, suggesting ScpD association with PSII that is repaired. Using antibodies that recognize both ScpC and ScpD, we found the ScpC protein, which is very similar in primary structure to ScpD, to also co-isolate with the PSII complex. In contrast, ScpE did not co-isolate with a major protein complex in thylakoids. A fourth member of the SCP family, ScpB, could not be immunodetected, but was found by mass spectrometry in samples co-isolating with ScpD-His. Therefore, ScpB may be associated with ScpD as well. No association between SCPs and PSI could be demonstrated. On the basis of these and other data presented, we suggest that members of the SCP family can associate with damaged PSII and can serve as a temporary pigment reservoir while PSII components are being replaced.