Structures and mechanisms of enzymes involved in bacterial chlorophyll biosynthesis

叶绿素和细菌叶绿素对于捕获全球能源需求至关重要。在细菌和植物中，这些色素分子是负责将光转化为化学能的光合装置的重要组成部分。我们的工作集中在以下（细菌）叶绿素生物合成酶的分子理解：3-乙烯基细菌叶绿素a水合酶（BchF）和3-羟乙基细菌叶绿素a脱氢酶（BchC）催化细菌叶绿素a合成的倒数第二步。O2-依赖或O2-非依赖镁原卟啉IX单甲酯环化酶是必不可少的第五环系统中发现的所有叶绿素的合成。所有必需的环化酶蛋白亚基的鉴定和表征是该项目的中心目标。光依赖性原叶绿素氧化还原酶（LPOR）执行严格的光依赖性催化。新的催化原理所采用的酶携带多种辅因子（如辅酶B12，S-腺苷蛋氨酸或二铁中心）的预期。结合生物化学和生物物理分析的晶体结构测定将揭示（细菌）叶绿素生物合成的后期步骤的原子理解。

Chlorophylls and bacteriochlorophylls are essential for the capturing of the global energy demand. In bacteria and plants, these pigment molecules are essential parts of the photosynthetic apparatus which is responsible for the conversion of light into chemical energy. Our work is focused on the molecular understanding of the following (bacterio)chlorophyll biosynthetic enzymes: 3-vinyl bacteriochlorophyllide a hydratase (BchF) and 3-hydroxyethyl bacteriochlorophyllide a dehydrogenase (BchC) catalyze the penultimate steps of bacteriochlorophyll a synthesis. O2-dependent or O2-independent Mg protoporphyrin IX monomethylester cyclase is essential for the synthesis of the fifth ring system found in all chlorophylls. The identification and characterization of all essential cyclase protein subunits is a central goal of this project. Light-dependent protochlorophyllide oxidoreductase (LPOR) performs a strictly light-dependent catalysis. Novel catalytic principles employed by enzymes carrying multiple cofactors (e.g. coenzyme B12, S-adenosyl methionine or diiron centers) are expected. Crystal structure determination in combination with biochemical and biophysical analyses will reveal the atomistic understanding of the late steps of (bacterio)chlorophyll biosynthesis.