TY - JOUR
T1 - Insights into energy quenching mechanisms and carotenoid uptake by orange carotenoid protein homologs
T2 - HCP4 and CTDH
AU - Sklyar, Jenia
AU - Wilson, Adjélé
AU - Kirilovsky, Diana
AU - Adir, Noam
N1 - Publisher Copyright:
© 2024 Elsevier B.V.
PY - 2024/4
Y1 - 2024/4
N2 - Photodamage to the photosynthetic apparatus by excessive light radiation has led to the evolution of a variety of energy dissipation mechanisms. A mechanism that exists in some cyanobacterial species, enables non-photochemical quenching of excitation energy within the phycobilisome (PBS) antenna complex by the Orange Carotenoid Protein (OCP). The OCP contains an active N-terminal domain (NTD) and a regulatory C-terminal domain (CTD). Some cyanobacteria also have genes encoding for homologs to both the CTD (CTDH) and the NTD (referred to as helical carotenoid proteins, HCP). The CTDH facilitates uptake of carotenoids from the thylakoid membranes to be transferred to the HCPs. Holo-HCPs exhibit diverse functionalities such as carotenoid carriers, singlet oxygen quenchers, and in the case of HCP4, constitutive OCP-like energy quenching. Here, we present the first crystal structure of the holo-HCP4 binding canthaxanthin molecule and an improved structure of the apo-CTDH from Anabaena sp. PCC 7120. We propose here models of the binding of the HCP4 to the PBS and the associated energy quenching mechanism. Our results show that the presence of the carotenoid is essential for fluorescence quenching. We also examined interactions within OCP-like species, including HCP4 and CTDH, providing the basis for mechanisms of carotenoid transfer from CTDH to HCPs.
AB - Photodamage to the photosynthetic apparatus by excessive light radiation has led to the evolution of a variety of energy dissipation mechanisms. A mechanism that exists in some cyanobacterial species, enables non-photochemical quenching of excitation energy within the phycobilisome (PBS) antenna complex by the Orange Carotenoid Protein (OCP). The OCP contains an active N-terminal domain (NTD) and a regulatory C-terminal domain (CTD). Some cyanobacteria also have genes encoding for homologs to both the CTD (CTDH) and the NTD (referred to as helical carotenoid proteins, HCP). The CTDH facilitates uptake of carotenoids from the thylakoid membranes to be transferred to the HCPs. Holo-HCPs exhibit diverse functionalities such as carotenoid carriers, singlet oxygen quenchers, and in the case of HCP4, constitutive OCP-like energy quenching. Here, we present the first crystal structure of the holo-HCP4 binding canthaxanthin molecule and an improved structure of the apo-CTDH from Anabaena sp. PCC 7120. We propose here models of the binding of the HCP4 to the PBS and the associated energy quenching mechanism. Our results show that the presence of the carotenoid is essential for fluorescence quenching. We also examined interactions within OCP-like species, including HCP4 and CTDH, providing the basis for mechanisms of carotenoid transfer from CTDH to HCPs.
KW - Crystal structure
KW - Cyanobacteria
KW - Non photochemical quenching
KW - Photoprotection
KW - Phycobilisome fluorescence quenching
UR - http://www.scopus.com/inward/record.url?scp=85189101715&partnerID=8YFLogxK
U2 - 10.1016/j.ijbiomac.2024.131028
DO - 10.1016/j.ijbiomac.2024.131028
M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???
C2 - 38521321
AN - SCOPUS:85189101715
SN - 0141-8130
VL - 265
JO - International Journal of Biological Macromolecules
JF - International Journal of Biological Macromolecules
M1 - 131028
ER -