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Nature:美科学家确定果蝇隐花色素的X-射线晶体结构

  1. X-射线晶体结构
  2. 果蝇隐花色素

来源:Natureaisa 2012-11-18 12:30

隐花色素/光修复酶家族的光受体调控所有生命中细胞对紫外线和蓝光的反应:隐花色素传导对于生长、发育、磁敏感性和生物钟有重要性的信号;光修复酶修复DNA中的光致损伤。 现在,Zoltowski等人确定了果蝇的全长度隐花色素的X-射线晶体结构。

隐花色素/光修复酶家族的光受体调控所有生命中细胞对紫外线和蓝光的反应:隐花色素传导对于生长、发育、磁敏感性和生物钟有重要性的信号;光修复酶修复DNA中的光致损伤。

现在,Zoltowski等人确定了果蝇的全长度隐花色素的X-射线晶体结构。他们发现,C-端螺旋体连接在一个已知与光修复酶中的DNA基质相结合的槽中,一个在演化中保留下来的色氨酸伸进该隐花色素的催化中心中,模仿能对DNA进行修复的光修复酶来识别DNA中所受的损伤。(生物谷Bioon.com)

Structure of full-length Drosophila cryptochrome

Brian D. Zoltowski, Anand T. Vaidya, Deniz Top, Joanne Widom, Michael W. Young & Brian R. Crane

The cryptochrome/photolyase (CRY/PL) family of photoreceptors mediates adaptive responses to ultraviolet and blue light exposure in all kingdoms of life1, 2, 3, 4, 5. Whereas PLs function predominantly in DNA repair of cyclobutane pyrimidine dimers (CPDs) and 6-4 photolesions caused by ultraviolet radiation, CRYs transduce signals important for growth, development, magnetosensitivity and circadian clocks1, 2, 3, 4, 5. Despite these diverse functions, PLs/CRYs preserve a common structural fold, a dependence on flavin adenine dinucleotide (FAD) and an internal photoactivation mechanism3, 6. However, members of the CRY/PL family differ in the substrates recognized (protein or DNA), photochemical reactions catalysed and involvement of an antenna cofactor. It is largely unknown how the animal CRYs that regulate circadian rhythms act on their substrates. CRYs contain a variable carboxy-terminal tail that appends the conserved PL homology domain (PHD) and is important for function7, 8, 9, 10, 11, 12. Here, we report a 2.3-? resolution crystal structure of Drosophila CRY with an intact C terminus. The C-terminal helix docks in the analogous groove that binds DNA substrates in PLs. Conserved Trp?536 juts into the CRY catalytic centre to mimic PL recognition of DNA photolesions. The FAD anionic semiquinone found in the crystals assumes a conformation to facilitate restructuring of the tail helix. These results help reconcile the diverse functions of the CRY/PL family by demonstrating how conserved protein architecture and photochemistry can be elaborated into a range of light-driven functions.

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