4MLA

Structure of maize cytokinin oxidase/dehydrogenase 2 (ZmCKO2)

4MLA の概要

• エントリーDOI: 10.2210/pdb4mla/pdb
• 関連するPDBエントリー: 3S1D 4ML8
• 分子名称: Cytokinin oxidase 2, FLAVIN-ADENINE DINUCLEOTIDE, ISOPROPYL ALCOHOL, ... (6 entities in total)
• 機能のキーワード: oxidoreductase, fad binding protein, flavoprotein, cytokinin oxidase/dehydrogenase, cytokinin binding
• 由来する生物種: Zea mays (maize)
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 115889.04

構造登録者

Morera, S.,Kopecny, D.,Briozzo, P.,Koncitikova, R. (登録日: 2013-09-06, 公開日: 2015-03-11, 最終更新日: 2016-03-23)

主引用文献

Kopecny, D.,Koncitikova, R.,Popelka, H.,Briozzo, P.,Vigouroux, A.,Kopecna, M.,Zalabak, D.,Sebela, M.,Skopalova, J.,Frebort, I.,Morera, S.
Kinetic and structural investigation of the cytokinin oxidase/dehydrogenase active site.
Febs J., 283:361-377, 2016

PubMed Abstract: Cytokinins are hormones that regulate plant development and their environmental responses. Their levels are mainly controlled by the cytokinin oxidase/dehydrogenase (CKO), which oxidatively cleaves cytokinins using redox-active electron acceptors. CKO belongs to the group of flavoproteins with an 8α-N1-histidyl FAD covalent linkage. Here, we investigated the role of seven active site residues, H105, D169, E288, V378, E381, P427 and L492, in substrate binding and catalysis of the CKO1 from maize (Zea mays, ZmCKO1) combining site-directed mutagenesis with kinetics and X-ray crystallography. We identify E381 as a key residue for enzyme specificity that restricts substrate binding as well as quinone electron acceptor binding. We show that D169 is important for catalysis and that H105 covalently linked to FAD maintains the enzyme's structural integrity, stability and high rates with electron acceptors. The L492A mutation significantly modulates the cleavage of aromatic cytokinins and zeatin isomers. The high resolution X-ray structures of ZmCKO1 and the E381S variant in complex with N6-(2-isopentenyl)adenosine reveal the binding mode of cytokinin ribosides. Those of ZmCKO2 and ZmCKO4a contain a mobile domain, which might contribute to binding of the N9 substituted cytokinins.

PubMed: 26519657
DOI: 10.1111/febs.13581

実験手法

X-RAY DIFFRACTION (2.04 Å)