Skip to main content
Research article - Peer-reviewed, 2013

Structure of the Homodimeric Glycine Decarboxylase P-protein from Synechocystis sp PCC 6803 Suggests a Mechanism for Redox Regulation

Hasse, Dirk; Andersson, Evalena; Carlsson, Gunilla; Masloboy, Axel; Hagemann, Martin; Bauwe, Hermann; Andersson, Inger


Glycine decarboxylase, or P-protein, is a pyridoxal 5-phosphate (PLP)-dependent enzyme in one-carbon metabolism of all organisms, in the glycine and serine catabolism of vertebrates, and in the photorespiratory pathway of oxygenic phototrophs. P-protein from the cyanobacterium Synechocystis sp. PCC 6803 is an (2) homodimer with high homology to eukaryotic P-proteins. The crystal structure of the apoenzyme shows the C terminus locked in a closed conformation by a disulfide bond between Cys(972) in the C terminus and Cys(353) located in the active site. The presence of the disulfide bridge isolates the active site from solvent and hinders the binding of PLP and glycine in the active site. Variants produced by substitution of Cys(972) and Cys(353) by Ser using site-directed mutagenesis have distinctly lower specific activities, supporting the crucial role of these highly conserved redox-sensitive amino acid residues for P-protein activity. Reduction of the 353-972 disulfide releases the C terminus and allows access to the active site. PLP and the substrate glycine bind in the active site of this reduced enzyme and appear to cause further conformational changes involving a flexible surface loop. The observation of the disulfide bond that acts to stabilize the closed form suggests a molecular mechanism for the redox-dependent activation of glycine decarboxylase observed earlier.


Crystal Structure; Decarboxylase; Disulfide; Pyridoxal Phosphate; Redox Regulation; P-protein; Glycine Decarboxylase

Published in

Journal of Biological Chemistry
2013, volume: 288, number: 49, pages: 35333-35345

Authors' information

Hasse, Dirk
Andersson, Evalena
Swedish University of Agricultural Sciences, Department of Molecular Biology
Carlsson, Gunilla
Uppsala University
Masloboy, Axel
University of Rostock
Hagemann, Martin
University of Rostock
Bauwe, Hermann
Andersson, Inger
Uppsala University

UKÄ Subject classification

Biochemistry and Molecular Biology

Publication Identifiers


URI (permanent link to this page)