《植物生理学报》 2018, 54(9): 1451-1458

软克里藻生长素合成关键酶TAA1初步功能研究

艾玉, 张振华, 郑玉玉, 钟伯坚, 朱自强^*

南京师范大学生命科学学院, 南京210023

通信作者：朱自强；E-mail: zqzhu@njnu.edu.cn

摘　要：

生长素是一类重要的内源植物激素, 在植物的生长发育过程中起重要作用。植物生长素的合成及信号转导机制目前已研究得比较清楚, 但其起源仍存在争议。吲哚-3-丙酮酸途径是植物生长素合成的主要途径之一, TAA1和YUCCA是该途径中的两类关键酶, 也常被作为生长素合成起源的研究线索。轮藻门是植物从水生到陆生登陆过程中的关键类群, 轮藻门的软克里藻(Klebsormidium flaccidum)已经完成了全基因组测序, 其基因组数据为研究生长素合成是否起源于轮藻提供了重要资源。本研究首先比对了软克里藻与其他植物物种间TAA1蛋白质氨基酸序列, 推测软克里藻TAA1蛋白(KfTAA1)可能具有催化色氨酸合成吲哚-3-丙酮酸的能力; 随后将KfTAA1过量表达在拟南芥taa1突变体(wei8-2)中, 观察KfTAA1是否可以回补taa1突变体的表型; 最后利用大肠杆菌(Escherichia coli)蛋白表达纯化系统, 体外纯化了GST-KfTAA1融合蛋白。我们的初步研究结果显示KfTAA1不能回补拟南芥taa1突变体表型, 推测KfTAA1可能不具有催化吲哚-3-丙酮酸合成的活性。

关键词：生长素; 起源; 软克里藻; KfTAA1

收稿：2018-07-03   修定：2018-08-18

资助：江苏高校优势学科建设工程。致谢 南京师范大学韩管助教授对本课题的建议。

Preliminary study on the function of TAA1, a key enzyme in auxin biosynthesis, in Klebsormidium flaccidum

AI Yu, ZHANG Zhen-Hua, ZHENG Yu-Yu, ZHONG Bo-Jian, ZHU Zi-Qiang^*

College of Life Sciences, Nanjing Normal University, Nanjing 210023, China

Corresponding author: ZHU Zi-Qiang; E-mail: zqzhu@njnu.edu.cn

Abstract:

Auxin is an important plant hormone, which is indispensable for plant growth and development. Although the mechanisms for auxin biosynthesis and signaling have been extensively studied, the origin of auxin is still under debate. Indole-3-pyruvic acid (IPyA) pathway is the major route for auxin biosynthesis in Arabidopis thaliana. TAA1 and YUCCAs are two types of crucial enzymes participating in this pathway. Land plants evolve from a linage of freshwater charophyte green algae, and that is why charophyte plants are critical species for understanding the evolutionary adaptation during plant landing. The genome of a charophyte Klebsormidium flaccidum has been completely sequenced, providing a useful resource for answering whether auxin biosynthesis origins from charophyte. Here we firstly made a sequence alignment of TAA1 amino acid sequences retrieved from different species, and found that KfTAA1 has conserved enzymatic reaction sites. Then we over-expressed KfTAA1 in A. thaliana mutants (wei8-2) and found that over-expression of KfTAA1 was not sufficient for complementation. Finally, we purified GST-KfTAA1 recombinant protein from Escherichia coli cells, which would be used for future enzymatic assays.

Key words: auxin; origin; Klebsormidium flaccidum; KfTAA1