Arabidopsis RIBA proteins: two out of three isoforms have lost their bifunctional activity in riboflavin biosynthesis.
Arabidopsis RIBA proteins: two out of three isoforms have lost their bifunctional activity in riboflavin biosynthesis.
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DOI：
10.3390/ijms131114086
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发表时间：
2012-10-31
影响因子：
5.6
通讯作者：
Grimm B
中科院分区：
文献类型：
--
作者：
Hiltunen HM;Illarionov B;Hedtke B;Fischer M;Grimm B
核黄素是黄素辅酶（FMN和FAD）的前体，是所有生物体所必需的。植物核黄素生物合成的两个重要酶步骤是由GTP环水解酶II （GCHII）和3,4-二羟基-2-丁酮-4-磷酸合成酶（DHBPS）组成的双功能RIBA酶完成的。被子植物共有一个小的RIBA基因家族，由三个成员组成。在拟南芥rfd1突变体和RIBA1反义系中，AtRIBA1表达的减少并没有被同时表达的AtRIBA2和AtRIBA3异构体所补充。RIBA1缺失植株的白化叶表型强度与AtRIBA1表达失活相关，而对AtRIBA2和AtRIBA3 mRNA丰度无显著影响。我们研究了这两种异构体不能充分补偿RIBA1表达缺失的原因。所有三种RIBA异构体均以GFP融合蛋白的形式易位到叶绿体中。有趣的是，AtRIBA2和AtRIBA3在保守肽结构域中都有氨基酸交换，这对两种酶的功能至关重要。用三种纯化的重组AtRIBA蛋白对GCHII和DHBPS进行体外活性测定，并分别与缺乏DHBPS和GCHII表达的大肠杆菌ribA和ribB突变体进行互补，证实了AtRIBA2和AtRIBA3的双功能丧失。系统发育分析表明，失去DHBPS活性的单功能、两部分RIBA3蛋白在气管植物进化的早期进化。
Riboflavin serves as a precursor for flavocoenzymes (FMN and FAD) and is essential for all living organisms. The two committed enzymatic steps of riboflavin biosynthesis are performed in plants by bifunctional RIBA enzymes comprised of GTP cyclohydrolase II (GCHII) and 3,4-dihydroxy-2-butanone-4-phosphate synthase (DHBPS). Angiosperms share a small RIBA gene family consisting of three members. A reduction of AtRIBA1 expression in the Arabidopsis rfd1mutant and in RIBA1 antisense lines is not complemented by the simultaneously expressed isoforms AtRIBA2 and AtRIBA3. The intensity of the bleaching leaf phenotype of RIBA1 deficient plants correlates with the inactivation of AtRIBA1 expression, while no significant effects on the mRNA abundance of AtRIBA2 and AtRIBA3 were observed. We examined reasons why both isoforms fail to sufficiently compensate for a lack of RIBA1 expression. All three RIBA isoforms are shown to be translocated into chloroplasts as GFP fusion proteins. Interestingly, both AtRIBA2 and AtRIBA3 have amino acid exchanges in conserved peptides domains that have been found to be essential for the two enzymatic functions. In vitro activity assays of GCHII and DHBPS with all of the three purified recombinant AtRIBA proteins and complementation of E. coli ribA and ribB mutants lacking DHBPS and GCHII expression, respectively, confirmed the loss of bifunctionality for AtRIBA2 and AtRIBA3. Phylogenetic analyses imply that the monofunctional, bipartite RIBA3 proteins, which have lost DHBPS activity, evolved early in tracheophyte evolution.
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影响因子：
14.9
作者：
Heazlewood, Joshua L.;Verboom, Robert E.;Millar, A. Harvey
通讯作者：
Millar, A. Harvey
影响因子：
7.2
作者：
Bendahmane, A;Querci, M;Baulcombe, DC
通讯作者：
Baulcombe, DC
影响因子：
7.4
作者：
Chincinska, Izabela A.;Liesche, Johannes;Kuehn, Christina
通讯作者：
Kuehn, Christina
DOI：
10.1046/j.1432-1033.2002.03239.x
发表时间：
2002-11-01
期刊：
EUROPEAN JOURNAL OF BIOCHEMISTRY
影响因子：
--
作者：
Kaiser, J;Schramek, N;Bacher, A
通讯作者：
Bacher, A
影响因子：
11.6
作者：
Cobessi, David;Dumas, Renaud;Alban, Claude
通讯作者：
Alban, Claude