阿拉伯芥中FIN219和光型態發生突變體之間的功能性研究

Investigation of functional relationship between FIN219 and photomorphogenic mutants in Arabidopsis

黃瓊慧(Chiung-Huei Huang)

指導教授 ： 謝旭亮

國立臺灣大學/生命科學院/植物科學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.00870

摘要

phyA (phytochrome A)為阿拉伯芥中遠紅光的接受體，在遠紅光中可抑制下胚軸延長，phyA的N端帶有一個可感受光訊息的色基，C端含有可傳遞訊息給下游基因的kinase區域。FIN219 (far-red insensitive 219)基因參與遠紅光下游的訊息傳遞，在遠紅光中fin219突變體具有下胚軸延長的外表型，FIN219的N端及C端各有一個coiled-coil區域可能與蛋白質間的交互作用有關；由分析得知，FIN219的N端和phyA的GAF區域其胺基酸序列上存在43%的相似性。GH3-10為阿拉伯芥中GH3-like基因家族中之ㄧ員，胺基酸序列親源性分析指出，GH3-10與FIN219有47%的相似性。因此欲探討GH3-10、phyA和FIN219之間的訊息傳遞與調控關係及PHYA其N端或C端的功能與作用機制。
由酵母菌雙雜合分析指出，FIN219與GH3-10的全長和phyA的C端有交互作用，上位性基因分析指出FIN219作用於phyA的下游，並且FIN219的表現僅在遠紅光phyA突變株中有明顯下降，暗示著FIN219蛋白質含量的多寡取決於植物在遠紅光下phyA是否存在。建構大量表現PHYA其N端或C端的轉殖株，觀察到在野生型背景中的轉殖株，於遠紅光下幼苗下胚軸比野生型短，CHS基因及花青素含量提升，葉綠素合成受抑制，且短日照下開花時間提早，顯現高度敏感的光形態發生外表型，但在phyA突變體背景中的轉殖株卻無上述表型。由此推測PHYA基因不論N端或C端皆具有傳遞訊息的功能，且須要完整PHYA蛋白質存在才具有作用。

關鍵字

FIN219 ； 光敏素A ； 阿拉伯芥

並列摘要

phyA is the photoreceptor of far-red light perception in Arabidopsis and mediates the inhibition of the hypocotyl elongation under FR light. phyA has two domains : the N-terminal photosensory domain with a chromophore-binding site and the C-terminal domain which contains signaling motifs such as a kinase domain. FIN219 (far-red insensitive 219) is involved in phytochrome A-mediated inhibition of hypocotyl elongation in FR signaling. Two coiled-coil domains, believed to be involved in protein-protein interactions, are found in FIN219 with one in the N-terminus and the other in the C-terminus. The N-terminal region of FIN219 has 43% similarity at amino acid levels to the GAF domain of PHYA. GH3-10 is a member of the GH3-like gene family in Arabidopsis. Sequence comparison between FIN219 and GH3-10 indicates that there is 47% identity at amino acid level. Hence, we try to understand the functional relationship among FIN219, GH3-10 and phyA to reveal the physiological significance of the similarity.
Yeast 2-hybrid interaction studies have revealed that FIN219 can interact with the full length of GH3-10 and the C-terminus of PHYA. Epistatic analysis reveals that FIN219 functions in downstream of the photoreceptor phyA, and its expression is much reduced in the phyA mutant only under FR condition, which suggests that FIN219 function is dependent on the presence of phyA. In addition, the transgenic plants overexpressing the full-length, N- or -C terminal regions of PHYA in wild type background display shorter hypocotyl phenotype as compared to wild type under FR. Other phenotypes such as anthocyanin accumulation, chlorophyll contents, CHS gene expression and flowering time mediated by phyA are consistently enhanced or the same as wild type when N- or -C terminal regions of PHYA are overexpressed in wild type rather than in phyA mutant, which implies that both the N-terminal and the C-terminal domains are functional and able to trigger signal transductions only in the presence of phyA.

並列關鍵字

FIN219 ； PHYA ； Arabidopsis

參考文獻

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