PDF(Pubmed)
Abstract：
Orange carotenoid proteins (OCPs) are unique photoreceptors that are critical for cyanobacterial photoprotection. Upon exposure to blue-green light, OCPs are activated from a stable orange form, OCPO, to an active red form, OCPR, which binds to phycobilisomes (PBSs) and performs photoprotective non-photochemical quenching (NPQ). OCPs can be divided into three main families: the most abundant and best studied OCP1, and two others, OCP2 and OCP3, which have different activation and quenching properties and are yet underexplored. Crystal structures have been acquired for the three OCP clades, providing a glimpse into the conformational underpinnings of their light-absorption and energy dissipation attributes. Recently, the structure of the PBS-OCPR complex has been obtained allowing for an unprecedented insight into the photoprotective action of OCPs. Here, we review the latest findings in the field that have substantially improved our understanding of how cyanobacteria protect themselves from the toxic consequences of excess light absorption. Furthermore, current research is applying the structure of OCPs to bio-inspired optogenetic tools, to function as carotenoid delivery devices, as well as engineering the NPQ mechanism of cyanobacteria to enhance their photosynthetic biomass production.
摘要：
橙类胡萝卜素蛋白（OCP）是独特的光感受器，对蓝细菌的光保护至关重要。暴露在蓝绿色光线下,OCPs从稳定的橙色形式被激活，OCPO,活跃的红色形式，OCPR,与藻胆体（PBS）结合并进行光保护性非光化学猝灭（NPQ）。OCPs可以分为三个主要家族：最丰富和研究最好的OCP1，以及其他两个，OCP2和OCP3具有不同的活化和猝灭特性，但仍未得到充分开发。已经获得了三个OCP进化枝的晶体结构，提供了对其光吸收和能量耗散属性的构象基础的一瞥。最近,已经获得了PBS-OCPR复合物的结构，从而可以前所未有地了解OCP的光保护作用。这里,我们回顾了该领域的最新发现，这些发现大大改善了我们对蓝藻如何保护自己免受过度光吸收的毒性后果的理解。此外，目前的研究是将OCPs的结构应用于生物启发光遗传学工具，用作类胡萝卜素输送装置，以及工程的NPQ机制的蓝藻，以提高其光合生物量的生产。
