The presence of phosphorylation form of D1 protein in its cross-linked aggregates in high light treated spinach leaves in vivo

• Published in: Chinese science bulletin 2006, Vol.51 (1), p.69-74
• Main Authors: Wei, Huimin, Guo, Junwei, Zhang, Shuang, Huang, Bo, Liu, Yinqiu, Du, Linfang
• Format: Article
• Language: English
• Subjects: D1蛋白质; 强光处理; 磷酸化
• ISSN: 1001-6538; 1861-9541
• DOI: 10.1007/s11434-005-1529-3

In the present study, using specific antibody against D1 protein, we detected four aggregates of D1 protein in thylakoid membranes from spinach leaves illuminated at high light （800--2500 μmol photons·m^-2·s^-1） for 3 h. Their accumulations were dependent on the light intensity to which the leaves had been subjected. Further immunoblot analysis indicated that 70 kD aggregate was a product of D1 protein cross-linked with CP43, 65 and 60 kD aggregate were two cross-linked products between D1 and D2 proteins, and 41 kD aggregate was one cross-linked D1 with α-subunit of cytochrome bss9 （Cyt bssg）. This result provided the evidence for the existence of the aggregation of the D1 protein in vivo. The maximal level of D1/Cyt bss9 aggregate occurred at 1000 μmol photons·m^-2·s^-1 but drastically decreased with further increasing light intensity. Immunoblot analysis with phosphothreonine （Thr （P）） antibody indicated that D1/CP43 and D1/Cyt bs59 aggregates contained the phosphorylated protein（s）. In vitro dephosphorylation experiment also showed that D1/Cyt bss9 and D1/CP43 aggregates lost the immunoreactivity with Thr （P） antibody after the phosphatase treatment of the membranes from high-light-illuminated leaves. Our results demonstrated that strong illumination of spinach leaves induced cross-linked products of D1 protein with its nearby polypeptides of PS Ⅱ, some of which contained the phosphorylated D1 protein.