High-Resolution Crystal Structure and Redox Properties of Chloroplastic Triosephosphate Isomerase from Chlamydomonas reinhardtii  

作　　者：Mirko Zaffagnini Laure Michelet Chiara Sciabolini Nastasia Di Giacinto Samuel Morisse Christophe H. Marchand Paolo Trost Simona Fermani Stephane D Lemaire 

机构地区：[1]Laboratoire de Biologie Moleculaire et Cellulaire des Eucaryotes, FRE3354 Centre National de la Recherche Scientifique, Universite Pierre et Marie Curie, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France [2]Laboratory of Plant Redox Biology, Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, via Irnerio 42, 40126 Bologna, Italy [3]Department of Chemistry 'G. Ciamician', University of Bologna, via Selmi 2, 40126 Bologna, Italy

出　　处：《Molecular Plant》2014年第1期101-120,共20页分子植物（英文版）

摘　　要：Triosephosphate isomerase （TPI） catalyzes the interconversion of glyceraldehyde-3-phosphate to dihydroxyacetone phosphate. Photosynthetic organisms generally contain two isoforms of TPI located in both cytoplasm and chloroplasts. While the cytoplasmic TPI is involved in the glycolysis, the chloroplastic isoform participates in the Calvin-Benson cycle, a key photosynthetic process responsible for carbon fixation. Compared with its cytoplasmic counterpart, the functional features of chloroplastic TPI have been poorly investigated and its three-dimensional structure has not been solved. Recently, several studies proposed TPI as a potential target of different redox modifications including dithiol/disulfide interchanges, glutathionylation, and nitrosylation. However, neither the effects on protein activity nor the molecular mechanisms underlying these redox modifications have been investigated. Here, we have produced recombinantly and purified TPI from the unicellular green alga Chlamydomonas reinhardtii （Cr）. The biochemical properties of the enzyme were delineated and its crystallographic structure was determined at a resolution of 1.1 A. CrTPI is a homodimer with subunits containing the typical （β/α）8-barrel fold. Although no evidence for TRX regulation was obtained, CrTPI was found to undergo glutathionylation by oxidized glutathione and trans-nitrosylation by nitrosoglutathione, confirming its sensitivity to multiple redox modifications.Triosephosphate isomerase （TPI） catalyzes the interconversion of glyceraldehyde-3-phosphate to dihydroxyacetone phosphate. Photosynthetic organisms generally contain two isoforms of TPI located in both cytoplasm and chloroplasts. While the cytoplasmic TPI is involved in the glycolysis, the chloroplastic isoform participates in the Calvin-Benson cycle, a key photosynthetic process responsible for carbon fixation. Compared with its cytoplasmic counterpart, the functional features of chloroplastic TPI have been poorly investigated and its three-dimensional structure has not been solved. Recently, several studies proposed TPI as a potential target of different redox modifications including dithiol/disulfide interchanges, glutathionylation, and nitrosylation. However, neither the effects on protein activity nor the molecular mechanisms underlying these redox modifications have been investigated. Here, we have produced recombinantly and purified TPI from the unicellular green alga Chlamydomonas reinhardtii （Cr）. The biochemical properties of the enzyme were delineated and its crystallographic structure was determined at a resolution of 1.1 A. CrTPI is a homodimer with subunits containing the typical （β/α）8-barrel fold. Although no evidence for TRX regulation was obtained, CrTPI was found to undergo glutathionylation by oxidized glutathione and trans-nitrosylation by nitrosoglutathione, confirming its sensitivity to multiple redox modifications.

关 键 词：triosephosphate isomerase three-dimensional structure TIM-barrel thiol-based redox regulation transnitrosylation. 

分 类 号：Q945.11[生物学—植物学] TQ426.97[化学工程]