Format

Send to

Choose Destination
Plant Physiol. 2017 Nov;175(3):1283-1303. doi: 10.1104/pp.17.01040. Epub 2017 Sep 21.

Paralogs of the C-Terminal Domain of the Cyanobacterial Orange Carotenoid Protein Are Carotenoid Donors to Helical Carotenoid Proteins.

Author information

1
Institute for Integrative Biology of the Cell, Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Université Paris-Sud, Université Paris-Saclay, 91198 Gif sur Yvette, France.
2
Institut de Biologie et Technologies de Saclay, Commissariat à l'Energie Atomique, 91191 Gif-sur-Yvette, France.
3
Institut National de la Recherche Agronomique, Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, ERL (Équipe de Recherche Labellisée) Centre National de la Recherche Scientifique 3559, Saclay Plant Sciences, F-78026 Versailles, France.
4
Institute for Integrative Biology of the Cell, Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Université Paris-Sud, Université Paris-Saclay, 91198 Gif sur Yvette, France diana.kirilovsky@cea.fr.

Abstract

The photoactive Orange Carotenoid Protein (OCP) photoprotects cyanobacteria cells by quenching singlet oxygen and excess excitation energy. Its N-terminal domain is the active part of the protein, and the C-terminal domain regulates the activity. Recently, the characteristics of a family of soluble carotenoid-binding proteins (Helical Carotenoid Proteins [HCPs]), paralogs of the N-terminal domain of OCP, were described. Bioinformatics studies also revealed the existence of genes coding for homologs of CTD. Here, we show that the latter genes encode carotenoid proteins (CTDHs). This family of proteins contains two subgroups with distinct characteristics. One CTDH of each clade was further characterized, and they proved to be very good singlet oxygen quenchers. When synthesized in Escherichia coli or Synechocystis PCC 6803, CTDHs formed dimers that share a carotenoid molecule and are able to transfer their carotenoid to apo-HCPs and apo-OCP. The CTDHs from clade 2 have a cysteine in position 103. A disulfide bond is easily formed between the monomers of the dimer preventing carotenoid transfer. This suggests that the transfer of the carotenoid could be redox regulated in clade 2 CTDH. We also demonstrate here that apo-OCPs and apo-CTDHs are able to take the carotenoid directly from membranes, while HCPs are unable to do so. HCPs need the presence of CTDH to become holo-proteins. We propose that, in cyanobacteria, the CTDHs are carotenoid donors to HCPs.

PMID:
28935842
PMCID:
PMC5664476
DOI:
10.1104/pp.17.01040
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center