CAREER: Breaking Down the Structure-function Relationships in Enzymes that Catabolize Chlorophyll

在化学系生命过程化学(CLP)项目的支持下，密歇根大学的Jennifer Bridwell-Rabb正在研究参与叶绿素降解的酶的结构和作用机制。叶绿素色素是光合作用不可或缺的一部分，光合作用是生物体将光能转化为化学能的过程。矛盾的是，使叶绿素色素利用阳光的相同性质，也有可能对光合作用生物体的健康产生负面影响。因此，类似于参与合成叶绿素的酶，参与降解这种色素的酶也是至关重要的。叶绿素降解酶保护生物免受有毒色素积累，支持作物抵抗环境胁迫的能力，并影响水果和蔬菜的寿命。尽管已知的叶绿素降解酶过多，但关于这些酶如何发挥其功能的知识存在严重差距。因此，本项目旨在培训研究人员使用结构生物学和酶学来阐明关键降解酶的机制。此外，该项目将培训研究人员向普通受众传播科学，并通过教育推广，吸引中学生以及更多的全球人口参与光合作用的基础科学。该研究项目特别侧重于使用结构、生化和生物物理技术来(I)建立叶绿素降解酶的结构-功能关系，(Ii)揭示与叶绿素分解代谢有关的机制细节，以及(Iii)确定光合作用有机体用来使叶绿素降解与细胞和环境条件同步的策略。为了实现这些目标，将对感兴趣的降解酶进行鉴定、分离、结构表征和机械研究。这项工作有可能解决我们对叶绿素色素如何以计算方式降解的机械理解上的缺陷。从长远来看，该项目的发现可以为操纵或利用叶绿素降解以改善作物生长、延长产品寿命并保护光合作用有机体免受生物和非生物胁迫的战略提供参考。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With the support of the Chemistry of Life Processes (CLP) program in the Division of Chemistry, Jennifer Bridwell-Rabb from the University of Michigan is investigating the structure and mechanisms of action of enzymes involved in chlorophyll degradation. Chlorophyll pigments are integral to photosynthesis, a process by which organisms convert light energy into chemical energy. Paradoxically, the same properties that poise chlorophyll pigments to harness sunlight, also have the potential to negatively impact the health of photosynthetic organisms. Therefore, akin to the enzymes involved in synthesizing chlorophyll, the enzymes involved in degrading this pigment are also critical. Chlorophyll degrading enzymes protect organisms from toxic pigment accumulation, support the ability of crops to resist environmental stressors, and impact the lifetimes of fruits and vegetables. Despite the plethora of known chlorophyll degrading enzymes, there is a critical gap in knowledge regarding how these enzymes perform their functions. Therefore, this project is aimed at training researchers to use structural biology and enzymology to illuminate the mechanisms of key degradative enzymes. Furthermore, this project will train researchers to accessibly communicate science to a general audience, and through educational outreach, will engage middle school students, as well as a greater global population, in the fundamental science of photosynthesis.This research project is specifically focused on using structural, biochemical, and biophysical techniques to (i) establish structure-function relationships in chlorophyll-degrading enzymes, (ii) reveal mechanistic details integral to chlorophyll catabolism, and (iii) identify the strategies that photosynthetic organisms use to synchronize chlorophyll degradation with cellular and environmental conditions. To accomplish these goals, degradative enzymes of interest will be identified, isolated, structurally characterized, and mechanistically studied. This work has potential to resolve deficits in our mechanistic understanding of how chlorophyll pigments are degraded in a calculated manner. In the long term, the findings of this project could inform strategies to manipulate or harness chlorophyll degradation to improve crop growth, elongate the lifetime of produce, and protect photosynthetic organisms from biotic and abiotic stressors.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.