Abstract
BackgroundPhotosystem II (PSII) is a highly conserved integral-membrane multi-subunit pigment-protein complex. The proteins, pigments, lipids, and ions in PSII need to be assembled precisely to ensure a proper PSII biogenesis. D1 is the main subunit of PSII core reaction center (RC), and is usually synthesized as a precursor D1. D1 maturation by the C-terminal processing protease CtpA is essential for PSII assembly. However, the detailed mechanism about how D1 maturation affects PSII assembly is not clearly elucidated so far. In this study, Arabidopsis thaliana CtpA mutant (atctpa: SALK_056011), which lacks the D1 mature process, was used to investigate the function of this process on PSII assembly in more details.ResultsWithout the C-terminal processing of precursor D1, PSII assembly, including PSII monomer, dimer, especially PSII supercomplexes (PSII SCs), was largely compromised as reported previously. Western blotting following the BN-2D-SDS PAGE revealed that although the assembly of PSII core proteins D2, CP43 and CP47 was affected by the loss of D1 mature process, the incorporation of CP43 was affected the most, indicated by its most reduced assembly efficiency into PSII SCs. Furthermore, the slower growth of yeast cells which were co-transformed with pD1 and CP43, when compared with the ones co-transformed with mature D1 and CP43, approved the existence of D1 C-terminal tail hindered the interaction efficiency between D1 and CP43, indicating the physiological importance of D1 mature process on the PSII assembly and the healthy growth of the organisms.ConclusionsThe knockout Arabidopsis atctpa mutant is a good material to study the unexpected link between D1 maturation and PSII SCs assembly. The loss of D1 maturation mainly affects the incorporation of PSII core protein CP43, an inner antenna binding protein, which functions in the association of LHCII complexes to PSII dimers during the formation of PSII SCs. Our findings here provide detailed supports of the role of D1 maturation during PSII SCs assembly in higher plants.
Highlights
Photosystem II (PSII) is a highly conserved integral-membrane multi-subunit pigment-protein complex
Our result showed that loss of mature D1 protein led to a compromised assembly of PSII PSII supercomplexes (SCs), which was caused by the abnormal assembly of reaction center (RC) complexes, especially the subunit of CP43, revealing the distinct and important function of D1 mature process during PSII SCs assembly
The results showed that only pD1 form was detected in atctpa mutant, while D1 protein existed in WT was the mature form (Fig. 1a)
Summary
Photosystem II (PSII) is a highly conserved integral-membrane multi-subunit pigment-protein complex. The proteins, pigments, lipids, and ions in PSII need to be assembled precisely to ensure a proper PSII biogenesis. D1 maturation by the C-terminal processing protease CtpA is essential for PSII assembly. Arabidopsis thaliana CtpA mutant (atctpa: SALK_056011), which lacks the D1 mature process, was used to investigate the function of this process on PSII assembly in more details. PSII is a highly conserved integral-membrane multisubunit pigment-protein complex found in cyanobacteria, algae, and plants. To ensure the proper PSII biogenesis, at least 20 different subunit proteins, as well as different pigments, lipids and ions need to be assembled precisely [7]. With the subsequential binding of CP43, OEC proteins and LMM proteins such as PsbK, PsbW, PsbZ, the RC47 complex transforms to PSII core monomer. With the dimerization of PSII monomer and the attachment of LHCII, PSII-LHCII supercomplexes is formed [7,8,9,10,11,12]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
