Environmental regulation of retinal and bacteriochlorophyll biosynthesis

视紫红蛋白是最简单的获取能量的光蛋白，群落元基因组学揭示了它们的合成基因在世界海洋中无处不在。其中包括微生物视紫红质(蛋白紫质(PR))，据估计，75%的海洋细菌和海洋表层水域中的古生菌中都存在这种物质。这种在表层海洋中丰富而广泛的光蛋白的发现挑战了太阳能只能通过基于叶绿素的光合作用转化为化学能在海洋生态系统中生长的观点。尽管在海洋生态系统中，光驱动的能量流通过PR的潜力可能很大，但这种类型的视紫红质的生理和生态功能仍然不确定，主要是因为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，即生色团视网膜。因为视紫红质只有一个与多肽视蛋白相关的视网膜发色团，所以视网膜分子的总数相当于PR的总数。智力优势：这个项目将使用PI最新开发的方案，通过野外和实验室操作来研究光、有机碳和痕量金属的有效性对PR和细菌叶绿素合成的影响。这样的实验将确定非生物因素对两种已知的细菌光异养代谢的影响。实验室研究将辅之以在不同海洋状况下按照光强、有机碳和痕量金属的空间和时间梯度收集的实地样本中的这些色素的分析。基因表达模式将根据田间和实验室中视网膜和细菌叶绿素浓度以及微生物生长反应的变化来确定。因此，观察性方法和操纵性方法的结合将解决海洋中基于视网膜的光化学能量转换的影响的基本问题，这一过程仍未得到很好的了解。更广泛的影响：南加州大学的本科生和研究生教育将通过积极参与联合实验室实验和实地工作来进一步发展。PIS研究计划包括通过请求支持来自洛杉矶地区其他学校的合格的未被充分代表的学生，以及积极指导南加州大学的本科高级研究论文，承诺对本科生进行培训。为了支持这一努力，Sanudo-Wilhelmy正在启动一项新的计划，在南加州大学招募少数族裔，利用科学会议和出版物中的奇卡诺人和美洲原住民促进会作为平台。该项目还将完全支持一名南加州大学研究生的论文工作，并为其成果的出版提供资金，以及允许他在全国会议上展示他的工作。该项目的科学和社会影响包括阐明能量转换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.