4XIW

Carbonic anhydrase Cah3 from Chlamydomonas reinhardtii in complex with acetazolamide

4XIW の概要

• エントリーDOI: 10.2210/pdb4xiw/pdb
• 分子名称: Carbonic anhydrase, alpha type, ZINC ION, 5-ACETAMIDO-1,3,4-THIADIAZOLE-2-SULFONAMIDE, ... (5 entities in total)
• 機能のキーワード: lyase, acetazolamide, photosystem ii-associated
• 由来する生物種: Chlamydomonas reinhardtii
• タンパク質・核酸の鎖数: 8
• 化学式量合計: 213414.45

構造登録者

Hainzl, T.,Grundstrom, C.,Benlloch, R.,Shevela, D.,Shutova, T.,Messinger, J.,Samuelsson, G.,Sauer-Eriksson, A.E. (登録日: 2015-01-07, 公開日: 2015-02-11, 最終更新日: 2024-11-13)

主引用文献

Benlloch, R.,Shevela, D.,Hainzl, T.,Grundstrom, C.,Shutova, T.,Messinger, J.,Samuelsson, G.,Sauer-Eriksson, A.E.
Crystal Structure and Functional Characterization of Photosystem II-Associated Carbonic Anhydrase CAH3 in Chlamydomonas reinhardtii.
Plant Physiol., 167:950-962, 2015

PubMed Abstract: In oxygenic photosynthesis, light energy is stored in the form of chemical energy by converting CO2 and water into carbohydrates. The light-driven oxidation of water that provides the electrons and protons for the subsequent CO2 fixation takes place in photosystem II (PSII). Recent studies show that in higher plants, HCO3 (-) increases PSII activity by acting as a mobile acceptor of the protons produced by PSII. In the green alga Chlamydomonas reinhardtii, a luminal carbonic anhydrase, CrCAH3, was suggested to improve proton removal from PSII, possibly by rapid reformation of HCO3 (-) from CO2. In this study, we investigated the interplay between PSII and CrCAH3 by membrane inlet mass spectrometry and x-ray crystallography. Membrane inlet mass spectrometry measurements showed that CrCAH3 was most active at the slightly acidic pH values prevalent in the thylakoid lumen under illumination. Two crystal structures of CrCAH3 in complex with either acetazolamide or phosphate ions were determined at 2.6- and 2.7-Å resolution, respectively. CrCAH3 is a dimer at pH 4.1 that is stabilized by swapping of the N-terminal arms, a feature not previously observed in α-type carbonic anhydrases. The structure contains a disulfide bond, and redox titration of CrCAH3 function with dithiothreitol suggested a possible redox regulation of the enzyme. The stimulating effect of CrCAH3 and CO2/HCO3 (-) on PSII activity was demonstrated by comparing the flash-induced oxygen evolution pattern of wild-type and CrCAH3-less PSII preparations. We showed that CrCAH3 has unique structural features that allow this enzyme to maximize PSII activity at low pH and CO2 concentration.

PubMed: 25617045
DOI: 10.1104/pp.114.253591

実験手法

X-RAY DIFFRACTION (2.6 Å)