Photochemical properties of the flavin mononucleotide-binding domains of the phototropins from Arabidopsis, rice, and Chlamydomonas reinhardtii
Photochemical properties of the flavin mononucleotide-binding domains of the phototropins from Arabidopsis, rice, and Chlamydomonas reinhardtii
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DOI：
10.1104/pp.002410
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发表时间：
2002-06-01
期刊：
影响因子：
7.4
通讯作者：
Briggs, WR
中科院分区：
文献类型：
--
作者：
Kasahara, M;Swartz, TE;Briggs, WR
向光蛋白（phot 1和phot 2，以前称为nph 1和npl 1）是蓝光受体介导的向光性，蓝光诱导的叶绿体移位，和蓝光诱导的气孔开放在拟南芥。趋光蛋白在其N末端含有两个光、氧或电压（LOV）结构域（LOV 1和LOV 2），每个结构域是发色团黄素单核苷酸（FMN）的结合位点。它们的C末端含有丝氨酸/苏氨酸蛋白激酶结构域。在这里，我们研究的动力学特性的LOV域的拟南芥phot 1和phot 2，水稻（水稻）phot 1和phot 2，和衣藻reinhardtii phot。当在大肠杆菌中表达时，来自所检测的所有趋光蛋白的纯化的LOV结构域紧密结合FMN并经历独立的光循环，其特征在于由蓝光诱导的荧光和吸收变化（T.酒井，T。香川，M. Kasahara，T.E. Swartz，J.M.克里斯蒂，W.R. Briggs，M. Wada，K. Okada [2001] Proc Natl Acad Sci USA 98：6969-6974; M.所罗门，J.M. Christie，E.埃克塞特，U. Lempert，W.R. Briggs [2000] Biochemistry 39：9401-9410）。光循环涉及FMN发色团的C（4a）碳的半胱氨酰加合物的光诱导形成，其随后在黑暗中分解。在每种情况下，光反应的相对量子效率和速率常数的LOV 1，LOV 2，和含有两个LOV域的肽的暗恢复。此外，从在昆虫细胞中表达的全长拟南芥photl和phot 2获得的数据与从在E.杆菌对于拟南芥和水稻向光蛋白，LOV域的phot 1不同的phot 2在其反应动力学特性和相对量子效率。因此，除了氨基酸序列不同之外，还可以根据其LOV结构域的光化学循环来区分向光蛋白。C.莱茵衣藻也经历与半胱氨酰加合物形成一致光活化光谱变化。因此，向光素家族在从单细胞藻类到高等植物的广泛进化范围内延伸。
Phototropins (phot1 and phot2, formerly designated nph1 and npl1) are blue-light receptors that mediate phototropism, blue light-induced chloroplast relocation, and blue light-induced stomatal opening in Arabidopsis. Phototropins contain two light, oxygen, or voltage (LOV) domains at their N termini (LOV1 and LOV2), each a binding site for the chromophore flavin mononucleotide (FMN). Their C termini contain a serine/threonine protein kinase domain. Here, we examine the kinetic properties of the LOV domains of Arabidopsis phot1 and phot2, rice (Oryza sativa) photl and phot2, and Chlamydomonas reinhardtii phot. When expressed in Escherichia coli, purified LOV domains from all phototropins examined bind FMN tightly and undergo a self-contained photocycle, characterized by fluorescence and absorption changes induced by blue light (T. Sakai, T. Kagawa, M. Kasahara, T.E. Swartz, J.M. Christie, W.R. Briggs, M. Wada, K. Okada [2001] Proc Natl Acad Sci USA 98: 6969-6974; M. Salomon, J.M. Christie, E. Knieb, U. Lempert, W.R. Briggs [2000] Biochemistry 39: 9401-9410). The photocycle involves the light-induced formation of a cysteinyl adduct to the C(4a) carbon of the FMN chromophore, which subsequently breaks down in darkness. In each case, the relative quantum efficiencies for the photoreaction and the rate constants for dark recovery of LOV1, LOV2, and peptides containing both LOV domains are presented. Moreover, the data obtained from full-length Arabidopsis photl and phot2 expressed in insect cells closely resemble those obtained for the tandem LOV-domain fusion proteins expressed in E. coli. For both Arabidopsis and rice phototropins, the LOV domains of photl differ from those of phot2 in their reaction kinetic properties and relative quantum efficiencies. Thus, in addition to differing in amino acid sequence, the phototropins can be distinguished on the basis of the photochemical cycles of their LOV domains. The LOV domains of C. reinhardtii phot also undergo light-activated spectral changes consistent with cysteinyl adduct formation. Thus, the phototropin family extends over a wide evolutionary range from unicellular algae to higher plants.