X-ray crystallographic and biochemical characterizations of a mutant photosystem II complex from Thermosynechococcus vulcanus with the psbTc gene inactivated by an insertion mutation.
The crystal structure of a photosystem II (PSII) dimer from Thermosynechococcus vulcanus with its psbTc gene inactivated by insertion mutation of an antibiotic cassette in a site in the C-terminal region was analyzed at 3.8 A resolution. In the crystal structure of the mutant PSII, the transmembrane helix of PsbTc remains, whereas the C-terminal loop of PsbTc has disappeared. In addition, the PsbM subunit, which seemed to be lost in a PsbTc-deletion mutant PSII of T. elongatus, is still present. The deletion of the C-terminal loop of PsbTc in the mutant PSII was verified by mass spectrometry. Thus, the insertion mutation of psbTc eliminated only the C-terminal loop of this subunit. Nevertheless, some features of the mutant PSII, namely a destabilization of the dimeric form and a slight decrease of the oxygen-evolving activity, were observed in the mutant, indicating that the C-terminal loop of PsbTc functions to maintain the stability of the PSII dimer and the activity of oxygen evolution.
Henmi
Takahiro
T
Department of Chemistry, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi, Osaka 558-8585, Japan.
Iwai
Masako
M
Ikeuchi
Masahiko
M
Kawakami
Keisuke
K
Shen
Jian Ren
JR
Kamiya
Nobuo
N
D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D002852:Chromatography, Ion Exchange; D018360:Crystallography, X-Ray / Q000379:methods*; D004591:Electrophoresis, Polyacrylamide Gel; D016254:Mutagenesis, Insertional; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000235:genetics; D011487:Protein Conformation; D046940:Synechococcus / Q000737:chemistry*
D001426:Bacterial Proteins; D045332:Photosystem II Protein Complex