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PROSITE documentation PDOC51443Phytochelatin synthase (PCS) domain profile
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PURL: https://purl.expasy.org/prosite/documentation/PDOC51443
Phytochelatins (PCs) are well known as the heavy metal-detoxifying peptides in higher plants, eukaryotic algae, fungi, nematode and cyanobacteria. These peptides, of the general structure (γ-Glu-Cys)n-Gly (with n=2-11), are enzymatically synthesized from the substrate glutathione (GSH). PCs are synthesized posttranslationally by the PC synthase (PCS) (EC 2.3.2.15), a γ-glutamylcysteine (γ-EC) transpeptidase. PC synthesis is proposed to have two distinct steps: (Step1) formation of γ-EC concomitant with the cleavage of Gly from GSH; and (Step 2) transfer of the γ-EC unit to an acceptor GSH molecule or an oligomeric PC peptide (PCn). Eukaryotic PCS typically has a conserved N-terminal domain and a variable C-terminal domain, both of which are cysteine-rich. The N-terminal core domain is sufficient to confer a PCS activity and therefore can be referred to the catalytic domain. Cyanobacterial PCS contains the conserved N-terminal catalytic domain but not the variable C-terminal domain found in eukaryotic PCSs. It can act as a GSH hydrolase and weakly as a peptide ligase [1,2].
The catalytic PCS domain belongs to the petidase family C83 of the papain superfamily of cysteine proteases [E1], with the structurally conserved "catalytic triad" and oxyanion hole in the active site. It has an overall "crescent" shape with α/β fold containing eight α-helices and six β-strands (see <PDB:2BTW>) [2].
The profile we developed covers the entire PCS domain.
Last update:March 2009 / First entry.
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PROSITE method (with tools and information) covered by this documentation:
| 1 | Authors | Tsuji N. Nishikori S. Iwabe O. Shiraki K. Miyasaka H. Takagi M. Hirata K. Miyamoto K. |
| Title | Characterization of phytochelatin synthase-like protein encoded by alr0975 from a prokaryote, Nostoc sp. PCC 7120. | |
| Source | Biochem. Biophys. Res. Commun. 315:751-755(2004). | |
| PubMed ID | 14975765 | |
| DOI | 10.1016/j.bbrc.2004.01.122 |
| 2 | Authors | Vivares D. Arnoux P. Pignol D. |
| Title | A papain-like enzyme at work: native and acyl-enzyme intermediate structures in phytochelatin synthesis. | |
| Source | Proc. Natl. Acad. Sci. U.S.A. 102:18848-18853(2005). | |
| PubMed ID | 16339904 | |
| DOI | 10.1073/pnas.0505833102 |
| E1 | Title | https://www.ebi.ac.uk/merops/cgi-bin/famsum?family=C83 |
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