CAREER:The High Light Inducible Polypeptides (HLIPs) in Synechocystis sp. PCC 6803: Regulation and Function in Cell Survival under High Light Intensity

光合生物在不同的环境中优化光的利用。关于这些生物在高强度光下应对过度吸收光能的保护机制，人们知之甚少。了解这些机制将有助于开发即使在恶劣环境条件下也能茁壮成长的作物。本项目以四种高光诱导多肽（high light inducible polypeptide， HLIP）的调控和功能为研究工具，研究Synecocystis sp. PCC 6803在强光下细胞存活的分子机制。首先，通过在hli启动子控制下携带sacB或gusA编码序列的基因工程菌株筛选hli调控缺陷突变体，寻找控制hli基因表达（编码hlip）的调控因子。其次，hlip在高强光下的细胞存活功能将通过突变体研究来确定，并通过筛选抑制因子来恢复在强光下死亡的四重hli缺失突变体的生存能力。第三，结合生物分离、质谱、蛋白质交联和突变体解剖等手段确定HLIP复合物。这些研究对了解光合生物强光适应的分子机制具有重要意义。hlip保存在包括作物在内的高等植物中，它们被认为是潜在的减压剂；因此，该研究将为hlip在提高作物产量方面的潜在应用提供重要线索。更广泛的影响：该项目旨在让来自代表性不足群体（主要是非裔美国人）的本科生和研究生积极参与，为理解光防护机制做出重大贡献。他们的部分培训将包括撰写论文和在科学会议上发表报告，这些会议将传播研究结果。该项目还包括参与一个现有的项目（阿肯色大学小石城分校少数族裔学生教学改善项目），该项目的重点是增加少数族裔学生的入学率和留校率，并帮助他们进入研究生和专业学校。此外，还将开设以实验为基础的课程。这些课程将为学生提供批判性思维和科学发现的机会，并帮助学生获得研究经验，并将其用于生物技术或教育领域的工作。

Photosynthetic organisms optimize utilization of light in different environments. Little is known about the protective mechanisms by which these organisms cope with excess absorption of light energy under high intensity light. Understanding these mechanisms will help in developing crops that are able to thrive even under harsh environmental conditions. The project focuses on regulation and function of four high light inducible polypeptides (HLIP) and using them as research tools to study the molecular mechanisms of cell survival under high intensity light in Synecocystis sp. PCC 6803. First, the regulators that control the expression of hli genes (encoding HLIPs) will be sought by screening for mutants defective in hli regulation using genetically engineered strains that carry sacB or gusA coding sequences under the control of hli promoters. Secondly, the functions of HLIPs in cell survival under high intensity light will be determined by mutant studies, and by screening for suppressors that restore the viability to a quadruple hli deletion mutant that dies in high light. Thirdly, the HLIP complexes will be determined by combining means of bio-separation, mass spectrometry, protein cross-linking and mutant dissection. These studies will contribute significantly to the understanding of the molecular mechanisms of high light acclimation in photosynthetic organisms. HLIPs are preserved in higher plants including crops and they are considered as potential stress reducers; therefore, the research will generate important leads for potential application of HLIPs to enhance crop production. Broader impacts: The project is designed to actively involve undergraduate and graduate students from underrepresented groups (mainly African-American) to make significant contributions to the understanding of the mechanisms of photoprotection. Part of their training will include writing papers and making presentations at scientific meetings at which the results of the studies will be disseminated. This project also include participation in an existing program (Teaching Enhancement Affect Minority Students at the University of Arkansas at Little Rock) that focuses on increasing the enrollment and retention of minority students and helping them to enter graduate and professional schools. In addition, laboratory-based courses will be created. These courses will provide students with opportunities for critical thinking and scientific discovery, and help students to gain research experience and parlay it into a job in either biotechnology or education.