Diversity and functional analysis of proteorhodopsin in marine Flavobacteria.
Diversity and functional analysis of proteorhodopsin in marine Flavobacteria.
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DOI：
10.1111/j.1462-2920.2012.02702.x
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发表时间：
2012-05
影响因子：
5.1
通讯作者：
Susumu Yoshizawa;Akira Kawanabe;Hiroyasu Ito;H. Kandori;K. Kogure
中科院分区：
文献类型：
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作者：
Susumu Yoshizawa;Akira Kawanabe;Hiroyasu Ito;H. Kandori;K. Kogure
蛋白视紫红质(PR)基因广泛存在于海洋原核生物中，在大肠杆菌中异源表达时具有光驱动质子泵的功能，提示光能通过PR在海洋环境中可能是重要的。然而，没有关于天然海洋细菌中PR质子泵活性的数据。在这里，我们展示了最近分离的海洋黄杆菌的光驱动质子泵活性(c.124H(+)PR(-1)min(-1))。在75株分离株中，38株携带PR基因。光照来自5个属的所有8个测试菌株的细胞悬浮液引发了显着的pH下降。质子泵活动的作用光谱与海面绿光场的光谱分布非常吻合。在溶解的膜组分中加入羟胺，使光谱转变为PR光漂白为视黄酮肟的形式，表明黄杆菌细胞膜中的PR将入射辐射中的光子剂量转换为膜电位形式的能量。我们的结果表明，PR介导的质子转运可以为天然黄杆菌细胞的ATP合成创造足够的膜电位。
Proteorhodopsin (PR) genes are widely distributed among marine prokaryotes and functions as light-driven proton pump when expressed heterologously in Escherichia coli, suggesting that light energy passing through PR may be substantial in marine environment. However, there are no data on PR proton pump activities in native marine bacteria. Here, we demonstrate light-driven proton pump activity (c. 124 H(+) PR(-1) min(-1) ) in recently isolated marine Flavobacteria. Among 75 isolates, 38 possessed the PR gene. Illumination of cell suspensions from all eight tested strains in five genera triggered marked pH drops. The action spectrum of proton pump activity closely matched the spectral distribution of the sea surface green light field. Addition of hydroxylamine to a solubilized membrane fraction shifted the spectrum to a form characteristic of PR photobleached into retinal oxime, indicating that PRs in flavobacterial cell membranes transform the photon dose in incident radiation into energy in the form of membrane potential. Our results revealed that PR-mediated proton transport can create the sufficient membrane potential for the ATP synthesis in native flavobacterial cells.