Environmental regulation of retinal and bacteriochlorophyll biosynthesis

视紫红质是最简单的能量收集光蛋白和社区宏基因组学已经揭示，它们的合成基因是普遍存在于世界各地的海洋。这些包括微生物视紫红质（蛋白视紫红质（PR）），估计75%的海洋细菌和海洋表面沃茨的古细菌中存在这种物质。在海洋表层发现这种丰富而广泛的光蛋白，挑战了太阳能只能通过基于叶绿素的光合作用转化为海洋生态系统生长所需的化学能的概念。虽然通过PR在海洋生态系统中的光驱动能量通量的潜力可能是显着的，这种类型的视紫红质的生理和生态功能仍然不确定，主要是由于缺乏直接测量这种光蛋白的技术。为了评估PR在海洋环境中的生态相关性，研究人员开发了一种新的分析技术来测量PR中光敏色素的浓度。由于视紫红质有一个单一的视网膜发色团与多肽视蛋白，视网膜分子的总数相当于PR的总数。智力优点：这个项目将采用PI的新开发的协议，研究光，有机碳和微量金属的影响，PR和细菌叶绿素合成使用现场和实验室操作。这些实验将确定非生物因素对两种已知细菌光合异养代谢的影响。除了实验室研究外，还将对在不同海洋学状况下沿着空间和时间梯度收集的实地样品中的这些色素、有机碳和微量金属进行分析。基因表达模式将与视网膜和细菌叶绿素浓度的变化以及田间和实验室中微生物的生长反应相一致。因此，观察和操作方法的结合，将解决有关视网膜的光化学能量转换在海洋中的影响，一个过程，仍然没有很好地理解的基本问题。更广泛的影响：在南加州大学的本科生和研究生教育将进一步通过积极参与联合实验室实验和实地工作。PI的研究计划包括通过请求支持目标来自其他洛杉矶合格的代表性不足的学生对本科生培训的承诺。地区学校，以及在南加州大学本科高级研究论文的积极辅导。为了支持这一努力，Sanudo-Wilhelmy正在南加州大学启动一项新的少数民族招聘计划，利用科学会议和出版物中的墨西哥裔和美洲土著人促进协会作为平台。该项目还将完全支持一名南加州大学研究生的论文工作，并为出版其成果提供资金，并允许他在国家会议上介绍他的工作。该项目的科学和社会影响包括阐明能量转化PR的生态重要性，如果没有它，我们将永远无法完全了解维持世界海洋主要生物过程的所有基本机制。

Rhodopsins are the simplest energy-harvesting photoproteins and community metagenomics have revealed that their synthesis genes are ubiquitous throughout the world oceans. These include microbial rhodopsin (proteorhodopsin (PR)), which occur in an estimated 75% of marine bacteria and archaea in oceanic surface waters. The discovery of this abundant and widespread photoprotein in the surface ocean has challenged the notion that solar energy can only be converted into chemical energy for growth in marine ecosystems through chlorophyll-based photosynthesis. Although the potential of light-driven energy flux in ocean ecosystems through PR could be significant, the physiological and ecological functions of this type of rhodopsin remains undetermined, mainly due to the lack of a technique for a direct measurement of this photoprotein. To evaluate the ecological relevance of PR in the marine environment, The investigators have developed a new analytical technique to measure the concentrations of the light-sensitive pigment in the PR, the chromophore retinal. Because rhodopsins have a single retinal chromophore associated with the polypeptide opsin, the total number of retinal molecules is equivalent to the total number of PR.Intellectual Merit:This project will employ the PI's newly developed protocol to examine the effects of light, organic carbon and trace metals availability on PR and bacteriochlorophyll synthesis using field and laboratory manipulations. Such experiments will establish the impact of abiotic factors on the two known bacterial photoheterotrophic metabolisms. The laboratory studies will be complemented with the analyses of those pigments in field samples collected along spatial and temporal gradients in light intensity, organic carbon and trace metals in different oceanographic regimes. Gene expression patterns will be determined in concert with changes in retinal and bacteriochlorophyll concentrations and microbial growth responses in the field and in the laboratory. Therefore, the combination of observational and manipulative approaches, will address fundamental questions in regard to the impact of retinal-based photochemical energy transformation in the ocean, a process that still is not well understood.Broader Impacts:Undergraduate and graduate education at USC will be furthered through active participation in the joint laboratory experiments and field work. The PIs research program includes a commitment to undergraduate student training by requesting support to target qualified underrepresented students from other L.A.-area schools, as well as active mentoring of undergraduate senior research theses at USC. In support of this effort Sanudo-Wilhelmy is starting a new initiative for minority recruitment at USC, using the Society for Advancement of Chicanos and Native Americans in Science meetings and publications as a platform. This project will also completely support the dissertation work of one USC graduate student and provide the funding for publication of his results, as well as to allow him to present his work at national meetings. The scientific and societal impacts of this project include elucidating the ecological importance of energy-transforming PR, without which we will never have a complete understanding of all of the essential mechanisms sustaining major biological processes in the world ocean.