Photoaffinity labeling of ribulose-1,5-bisphosphate carboxylase/oxygenase activase with ATP gamma-benzophenone. Identification of the ATP gamma-phosphate binding domain

• Published in: The Journal of biological chemistry Vol. 268; no. 19; pp. 14239 - 14244
• Main Authors: Salvucci, M.E, Rajagopalan, K, Sievert, G, Haley, B.E, Watt, D.S
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Biochemistry and Molecular Biology 05-07-1993
• Subjects: Adenosine Diphosphate - metabolism; ADENOSINE TRIPHOSPHATE; Adenosine Triphosphate - analogs & derivatives; Adenosine Triphosphate - metabolism; ADENOSINTRIFOSFATO; Affinity Labels - metabolism; Amino Acid Sequence; Analytical, structural and metabolic biochemistry; Benzophenones - metabolism; Binding Sites; Biological and medical sciences; CETONAS; CETONE; COMPOSE AROMATIQUE; COMPUESTOS AROMATICOS; Electrophoresis, Polyacrylamide Gel; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Kinetics; Miscellaneous; Molecular Sequence Data; Nicotiana - enzymology; NICOTIANA TABACUM; Peptide Fragments - isolation & purification; Photolysis; Plant Proteins; Plants, Toxic; REACCIONES QUIMICAS; REACTION CHIMIQUE; RIBULOSA-BIFOSFATO CARBOXILASA; RIBULOSE-BISPHOSPHATE CARBOXYLASE; Ribulose-Bisphosphate Carboxylase - isolation & purification; Ribulose-Bisphosphate Carboxylase - metabolism; Enzyme; Dicotyledones; Angiospermae; Spermatophyta; Binding site; Solanaceae; Photoaffinity labelling; Inactivation; Nicotiana tabacum; ATP; Benzophenone
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)85232-8

The phosphate-binding domain of the ATP-binding site of tobacco Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) activase was elucidated by photoaffinity labeling with a monoanhydride of ADP with N-(4-(benzoyl)phenylmethyl)phosphoramide ([gamma-(32)P] ATP gamma BP). Covalent incorporation of [gamma-(32)P]ATP gamma BP into the 42-kDa Rubisco activase subunit was dependent upon irradiation with ultraviolet light. Photolabeling of Rubisco activase with ATP gamma BP exhibited saturation kinetics; the apparent Kd for photolabeling was 5 micromolar. Two lines of evidence showed that ATP gamma BP modified Rubisco activase at the ATP-binding domain. First, physiological concentrations of ATP and ADP afforded complete protection against photolabeling of Rubisco activase by ATP gamma BP. Second, photolysis of Rubisco activase in the presence of ATP gamma BP decreased both the ATPase and the Rubisco activating activities. Inactivation of enzyme activity was dependent on ATP gamma BP concentration and could be prevented by including ADP during photolabeling. The region of Rubisco activase that was modified by ATP gamma BP was identified by isolating photolabeled peptides. Sequence analysis showed that ATP gamma BP modified Rubisco activase in two distinct regions; one region, S117-A136, is adjacent to the P-loop and the other region, V223-T234, exhibits homology to a region of adenylate kinase that ligates the essential metal ion. Photolabeling of these two regions of Rubisco activase was consistent with modification of the ATP gamma-phosphate-binding domain of Rubisco activase with ATP gamma BP