Wang X, Tabita F R
Department of Microbiology, Biotechnology Center, Ohio State University, Columbus 43210.
J Bacteriol. 1992 Jun;174(11):3607-11. doi: 10.1128/jb.174.11.3607-3611.1992.
Purified inactivated form I ribulose 1,5-bisphosphate carboxylase/oxygenase (form I RubisCO) of Rhodobacter sphaeroides was activated by ATP and, to some extent, by other adenylates and nucleotides. Reactivation in the presence of ATP occurred by a time-dependent and concentration-dependent process which appeared to be irreversible. The carbamylated form of inactivated form I RubisCO was less susceptible to ATP-mediated reactivation than the uncarbamylated inactivated enzyme. In some cases, ATP analogs could mimic the reactivation process; one analog, adenylyl(beta, gamma-methylene)-diphosphonate, was found to partially block ATP-mediated reactivation but could not block reactivation induced by Mg(II). Concomitant with the recovery of enzymatic activity, the migration of the inactivated form I RubisCO on nondenaturing and sodium dodecyl sulfate gels changed from a pattern that was characteristic of inactivated enzyme to a pattern that was identical to that of the active protein. It was further found that discrete proportions of active enzyme and the chaperonin 60 protein of R. sphaeroides aggregated in the presence of ATP. The form I RubisCO is thus proposed to contain a specific ATP-binding site that may contribute to both the regulation of activity and the assembly of active enzyme.
球形红杆菌纯化的失活I型核酮糖-1,5-二磷酸羧化酶/加氧酶（I型RubisCO）可被ATP激活，在一定程度上也可被其他腺苷酸和核苷酸激活。在ATP存在下的再激活通过一个时间和浓度依赖性过程发生，该过程似乎是不可逆的。与未氨甲酰化的失活酶相比，失活I型RubisCO的氨甲酰化形式对ATP介导的再激活不太敏感。在某些情况下，ATP类似物可以模拟再激活过程；发现一种类似物腺苷酰（β，γ-亚甲基）-二磷酸可以部分阻断ATP介导的再激活，但不能阻断Mg(II)诱导的再激活。伴随着酶活性的恢复，失活I型RubisCO在非变性和十二烷基硫酸钠凝胶上的迁移模式从失活酶的特征模式转变为与活性蛋白相同的模式。进一步发现，在ATP存在下，活性酶和球形红杆菌伴侣蛋白60的离散比例会聚集。因此，I型RubisCO被认为含有一个特定的ATP结合位点，该位点可能有助于活性调节和活性酶的组装。
