Origin, phylogeny, evolution and structural basis of light-driven protochlorophyllide reduction

原叶绿素的还原是产生（细菌）叶绿素的复杂生物合成途径中的一个关键步骤。在产氧光养生物如植物、藻类和蓝细菌中，该步骤由光驱动的原叶绿素（Pchlide）氧化还原酶（LPORs）催化。在进化的背景下，目前广泛接受的是，LPORs首先在蓝藻中发明，然后通过内共生转移到植物和藻类。与这个长期持有的paradigm相反，我们最近在不产氧α-变形杆菌Dinoroseasthishiopterium DFL 12 T中鉴定了功能性光驱动的LPOR（未发表的数据，参见初步工作）。这提出了关于叶绿素生物合成和光合作用的进化的深远问题，并表明在例如不可培养的菌株和/或特化微生物中可能发现另外的功能多样的LPOR。该提案旨在利用尚未探索的宏基因组/环境来源的序列多样性，以阐明进化起源，遗传学，以及光驱动的原叶绿素还原的结构和功能基础。为了实现这些目标，有必要将微生物学家、分子生物学家、生物化学家、生物信息学家和结构生物学家的跨学科专业知识联合收割机。虽然体内和体外功能和结构数据（Krauss和Drepper工作组）将为LPOR酶家族光驱动Pchlide还原的功能适应和机制方面提供广泛的见解，但Arndt von Haeseler工作组将建立的进化观点预计将提供新的维度和丰富的范围。

The reduction of protochlorophyllide represents one key steps in the complex biosynthesis pathway yielding (bacterio)chlorophyll. In oxygenic phototrophs such as plants, algae and cyanobacteria this step is catalyzed by light-driven protochlorophyllide (Pchlide) oxidoreductases (LPORs). In an evolutionary context, it is currently widely accepted that LPORs were first -invented- in cyanobacteria and were then transferred via endosymbiosis to plants and algae. In contrast to this long held paragdigm, we have recently identified a functional light-driven LPOR in the anoxygenic alpha-proteobacterium Dinoroseobacter shibae DFL12T (unpublished data, see preliminary work). This raises far reaching questions regarding the evolution of chlorophyll biosynthesis and photosynthesis and suggests that additional functionally diverse LPORs might be found in e.g. unculturable strains and/or specialized microbes. The proposal aims to exploit the yet unexplored sequence diversity of metagenomic/environmental sources to elucidate the evolutionary origin, phylogeny, as well as the structural and functional basis of light-driven protochlorophyllide reduction. To achieve these goals, it is necessary to combine the interdisciplinary expertise of microbiologists, molecular biologists, biochemists, bioinformaticians and structural biologists. While in vivo and in vitro functional and structural data (working groups Krauss and Drepper) will provide broad insight into functional adaptation and mechanistic aspects of light-driven Pchlide reduction by the LPOR family of enzymes, the evolutionary perspective which will be established by the working group of Arndt von Haeseler is expected to provide a new dimension and enriched scope.