EFFECTS OF ENERGIZATION AND SUBSTRATES ON THE REACTIVITIES OF LYSINE RESIDUES OF THE CHLOROPLAST ATP SYNTHASE BETA SUBUNIT

Research Project

Project/Area Number	05680562
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Functional biochemistry
Research Institution	TEIKYO UNIVERSITY
Principal Investigator	TAKAKI Mizuho TEIKYO UNIV.PHARM.SCI.RESEARCH.ASSOCI., 薬学部, 助手 (00112764)
Project Period (FY)	1993 – 1994
Project Status	Completed (Fiscal Year 1994)
Budget Amount *help	¥2,100,000 (Direct Cost: ¥2,100,000) Fiscal Year 1994: ¥600,000 (Direct Cost: ¥600,000) Fiscal Year 1993: ¥1,500,000 (Direct Cost: ¥1,500,000)
Keywords	CHLOROPLAST / ATP SYNTHASE / ATP SYNTHASE BETA SUBUNIT / LYSINE RESIDUES / PYRIDOXAL 5'-PHOSPHATE / CONFORMATION / ENERGIZAITON / ADP / 葉緑体ATP合成酵素 / betaサブユニット / 高次構造変化 / ATP結合部位 / ADP結合部位 / リン酸結合部位
Research Abstract	Incubation of chloroplast thylakoids with pyridoxal 5'-phosphate for a short time (5s) modified the lysine residues of the beta subunit of ATP synthase. Except for lysine residues in the N-terminal and C-terminal regions, glycine-rich P-loop (GGAGVGK^<178>T), Lys154, and Lys167-containing peptide (P-peptide) exhibited especially high reactivity with pyridoxal 5'-phosphate. Energization of thylakoids or addition of substrates (ADP,Pi, ATP) affected the modifications of P-peptide, Lys447, and Lys399. P-peptide ; Substrates inhibited the modification. 0.5mM ADP inhibited it by 80%. Energization enhanced the inhibitory effects of substrates. Lys447 ; Substrates inhibited the modification. 0.5mM ADP inhibited it by 60%. Lys399 ; The reactivity depended on the transmembrane DELTAmu_<H+>. With increasing DELTAmu_<H+>, the reactivity decreased. These results suggest the energy-dependent conformation changes at the catalytic nucleotide binding site and around Lys399. The former increases the affinity of the site for substrates. Substrate binding at the catalytic site changes the conformaiton around Lys447.