tailieunhanh - Báo cáo khoa học: Extrinsic proteins of photosystem II An intermediate member of the PsbQ protein family in red algal PS II

The oxygen-evolving photosystem II (PS II) complex of red algae contains four extrinsic proteins of 12 kDa, 20 kDa, 33 kDa and cytc-550, among which the 20 kDa protein is unique in that it is not found in other cloned the gene for the 20-kDa protein from a red algaCyanidium caldarium. The gene consists of a leader sequence which can be divided into two parts: one for transfer across the plastid envelope and the other for transfer into thylakoid lumen, indicating that the gene is encoded by the nuclear genome | Eur. J. Biochem. 270 4156-4163 2003 FEBS 2003 doi Extrinsic proteins of photosystem II An intermediate member of the PsbQ protein family in red algal PS II Hisataka Ohta1 2 Takehiro Suzuki1 Masaji Ueno1 Akinori Okumura1 Shizue Yoshihara1 Jian-Ren Shen3 and Isao Enami1 1 Department of Biology Faculty of Science and 2Tissue Engineering Research Center Tokyo University of Science Japan 3Department of Biology Faculty of Science Okayama University and PRESTO JST Japan The oxygen-evolving photosystem II PS II complex of red algae contains four extrinsic proteins of 12 kDa 20 kDa 33 kDa and cyt c-550 among which the 20 kDa protein is unique in that it is not found in other organisms. We cloned the gene for the 20-kDa protein from a red alga Cyanidium caldarium. The gene consists of a leader sequence which can be divided into two parts one for transfer across the plastid envelope and the other for transfer into thylakoid lumen indicating that the gene is encoded by the nuclear genome. The sequence of the mature 20-kDa protein has low but significant homology with the extrinsic 17-kDa PsbQ protein of PS II from green algae Volvox Carteri and Chlamydomonas reinhardtii as well as the PsbQ protein of higher plants and PsbQ-like protein from cyanobacteria. Cross-reconstitution experiments with combinations of the extrinsic proteins and PS IIs from the red alga Cy. calda-rium and green alga Ch. reinhardtii showed that the extrinsic 20-kDa protein was functional in place of the green algal 17-kDa protein on binding to the green algal PS II and restoration of oxygen evolution. From these results we conclude that the 20-kDa protein is the ancestral form of the extrinsic 17-kDa protein in green algal and higher plant PS IIs. This provides an important clue to the evolution of the oxygen-evolving complex from prokaryotic cyanobacteria to eukaryotic higher plants. The gene coding for the extrinsic 20-kDa protein was named psbQ prime . Keywords .