Collaborative Research: Biochemical, genetic and structural studies of bilin lyases

合作研究：胆素裂解酶的生化、遗传和结构研究

• 批准号: 2017164
• 负责人: David Kehoe
• 金额: $ 43.26万
• 依托单位: Indiana University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-05-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2017164&HistoricalAwards=false
• 关键词: Collaborative; Research; Biochemical; genetic; structural

Marine phytoplankton at the base of the food web take carbon dioxide from the atmosphere during photosynthesis and turn it into a form that all life in the ocean can use. This project aims to study how a group of widespread phytoplankton called Synechococcus succeed in photosynthesis by matching their pigment composition to the light environment. This phenomenon, known as chromatic acclimation, involves a few genes that allow these microbes to incorporate different pigments depending on the available color of light filtering through the ocean. The team will characterize the structures and functions of the proteins encoded by these genes. Findings of this research will help predict how marine Synechococcus and the food chain are affected by changes in the ocean. These studies promise to expand the repertoire of fluorescent bio-imaging probes for biotechnology. This research will train 4 graduate students, 6-8 undergraduate students, 6 high school teachers, and 3-6 high school students in genetics, biochemistry and structural biology. Outreach activities include camps which will increase the persistence and diversity of STEM majors, high school teacher training modules, and promotion of the public’s awareness of science.Marine Synechococcus achieve extensive pigment diversity via post-translational modifications of phycobiliproteins that constitute the photosynthetic antennae called phycobilisomes. Phycobiliprotein biogenesis involves attachment of chemically distinct bilin pigments to these proteins via enzymatic reactions catalyzed by bilin lyases. Bilin lyase-isomerases attach a green-absorbing bilin and isomerize it to a blue-absorbing bilin. These enzymes play a key role in Type IV Chromatic Acclimation (CA4), in which the cells change color as a result of massive restructuring of their phycobilisomes under blue or green light. The ability to perform CA4 is conferred by a small genomic island composed of 4-5 genes, including a bilin lyase. However, the mechanism by which Synechococcus utilizes different bilin lyases and lyase-isomerases to achieve their pigment diversity remains elusive. This research integrates biochemistry, molecular genetics and structural biology to study a group of uncharacterized bilin lyases involved in CA4. The project aims are: (1) to identify and characterize novel lyases and lyase-isomerases responsible for key changes in bilin content that occur during CA4; (2) to determine the functional role of Unk10, a novel protein encoded in the CA4 genomic island, which is hypothesized to influence chromophorylation at those bilin sites involved in CA4; (3) to combine crystallography and mutagenesis to establish the reaction mechanism and structural basis that distinguishes between lyase and lyase-isomerase functions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

位于食物链底部的海洋浮游植物通过光合作用从大气中吸收二氧化碳，并将其转化为海洋中所有生命都可以利用的一种形式。这个项目旨在研究一组广泛分布的浮游植物——聚藻球菌是如何通过将它们的色素组成与光环境相匹配来成功进行光合作用的。这种现象被称为色适应，涉及到一些基因，这些基因允许这些微生物结合不同的色素，这取决于通过海洋过滤的光的可用颜色。研究小组将描述由这些基因编码的蛋白质的结构和功能。这项研究的发现将有助于预测海洋聚球菌和食物链如何受到海洋变化的影响。这些研究有望扩大荧光生物成像探针在生物技术中的应用范围。本研究将培养遗传学、生物化学和结构生物学方面的研究生4名，本科生6-8名，高中教师6名，高中学生3-6名。拓展活动包括增加STEM专业的持久性和多样性的营地，高中教师培训模块，以及提高公众的科学意识。海洋聚藻球菌通过藻胆蛋白的翻译后修饰实现广泛的色素多样性，藻胆蛋白构成光合触角，称为藻胆体。藻胆蛋白的生物生成涉及化学上不同的胆磷脂色素通过胆磷脂裂解酶催化的酶反应附着到这些蛋白质上。胆囊蛋白裂解酶-异构酶将吸收绿色的胆囊蛋白与吸收蓝色的胆囊蛋白异构。这些酶在IV型颜色驯化（CA4）中起着关键作用，在这种情况下，细胞在蓝光或绿光下由于藻胆体的大量重组而改变颜色。执行CA4的能力是由一个由4-5个基因组成的小基因组岛赋予的，包括一个十亿蛋白裂解酶。然而，聚珠球菌利用不同的胆磷脂裂解酶和裂解酶异构酶实现色素多样性的机制尚不清楚。本研究将生物化学、分子遗传学和结构生物学相结合，对CA4参与的一组未被表征的胆磷脂裂解酶进行了研究。该项目的目标是：(1)鉴定和表征在CA4过程中负责十亿蛋白含量关键变化的新型裂解酶和裂解酶异构酶；(2)确定CA4基因组岛中编码的新蛋白Unk10的功能作用，该蛋白被假设影响CA4中涉及的十亿蛋白位点的色素磷酸化；(3)结合晶体学和诱变学，建立裂解酶和裂解酶异构酶功能的反应机理和结构基础。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Molecular bases of an alternative dual-enzyme system for light color acclimation of marine Synechococcus cyanobacteria

• DOI: 10.1073/pnas.2019715118
• 发表时间: 2021-03-02
• 期刊: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• 影响因子: 11.1
• 作者: Grebert, Theophile;Nguyen, Adam A.;Partensky, Frederic
• 通讯作者: Partensky, Frederic