Resolving cryptic aspects of cryptochrome signaling.
Resolving cryptic aspects of cryptochrome signaling.
复制标题
解决隐花色素信号传导的神秘方面。
DOI：
10.1073/pnas.1511092112
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发表时间：
2015
影响因子：
11.1
通讯作者：
Zoltowski,BrianD
中科院分区：
文献类型：
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作者：
Zoltowski,BrianD
100多年来，人们已经知道蓝光光感受器在弱光条件下调节植物的生长和发育。这些光感受器被称为隐花植物（cryptochomes），因为它们在隐花植物中的重要性以及它们的功能和光化学的神秘方面（1，2）。尽管在其结构和光化学方面取得了数十年的进展（下文讨论），但CRY的光循环和信号机制的几个要素仍然存在激烈的争论。这些争论集中在CRY/光解酶家族（CPF）内的序列保守性上。尽管序列高度相似，CPF成员表现出从DNA修复酶（光裂合酶）到蓝光调节的生长，发育和不同生物体的昼夜节律的功能（3）。在所有情况下，CPF的功能取决于结合的黄素腺嘌呤二核苷酸（FAD）辅因子，该辅因子在几种氧化还原状态之间进行相互转换（图1）。目前，FAD的基态和激发态的性质，次级色素的存在和作用，以及三个Trp残基（Trp三联体）的保守序列的要求仍然存在争议（3，4）。争论源于解决体外光化学实验和体内生物学功能之间矛盾的困难（4）。这些冲突因CPF大家庭内部的明显分歧而进一步加剧。例如，据报道，拟南芥AtB 1和AtB 2蛋白在功能上对Trp三联体的需求不同：Trp三联体不是AtB 2中信号传导所需的（5），但据报道是AtB 1体内功能所需的（6）。在PNAS中，Gao等人优雅地证明了Trp三联体确实不是AtB 1体内功能所必需的，并且Trp三联体突变体的光化学活化不依赖于ATP或其他代谢物（7）。通过这种方式，Gao等人澄清了关于Trp三联体生物学作用的CRY化学和功能中的两个冲突。因此，他们提出了一个更统一的理解CRY光化学。
For over 100 years it has been known that a blue light photoreceptor regulates growth and development in plants under low-light conditions. These photoreceptors were termed cryptochomes (CRYs) because of their importance in cryptogamic plants and the cryptic aspects of their function and photochemistry (1, 2). Despite decades of progress into their structure and photochemistry (discussed below), several elements of CRY’s photocycle and signaling mechanisms remain fiercely debated. These debates center on sequence conservation within the CRY/photolyase family (CPF). Despite high sequence similarities, CPF members demonstrate functions ranging from DNA repair enzymes (photolyases) to blue light-regulated growth, development, and circadian rhythms in diverse organisms (CRYs)(3). In all cases, CPF function hinges upon a bound flavin adenine dinucleotide (FAD) cofactor that undergoes interconversion between several redox states (Fig. 1). Currently, the nature of the ground and excited states of FAD, the presence and role of secondary pigments, and the requirement of a conserved sequence of three Trp residues (Trp triad) remain controversial (3, 4). Debates stem from the difficulties of resolving contradictions between in vitro photochemical experiments and in vivo biological function (4). These conflicts are further exacerbated by apparent differences within the CPF family. For instance, the Arabidopsis thaliana AtCRY1 and AtCRY2 proteins reportedly differ in the requirement of the Trp triad for function: the Trp triad is not required for signaling in CRY2 (5), but was reported to be required for CRY1 function in vivo (6). In PNAS, Gao et al. elegantly demonstrate that the Trp triad is indeed not required for in vivo function of AtCRY1 and that photochemical activation of Trp triad mutants is not dependent upon ATP or other metabolites (7). In this manner, Gao et al. clarify two conflicts in CRY chemistry and function regarding the biological role of the Trp triad. Thereby, they present a more unified understanding of CRY photochemistry.