Catanese C A, Emerich D W, Zahler W L
Department of Biochemistry, University of Missouri-Columbia 65211.
J Bacteriol. 1989 Sep;171(9):4531-6. doi: 10.1128/jb.171.9.4531-4536.1989.
Adenylate cyclase and cyclic AMP (cAMP) phosphodiesterase have been identified and partially characterized in bacteroids of Bradyrhizobium japonicum 3I1b-143. Adenylate cyclase activity was found in the bacteroid membrane fraction, whereas cAMP phosphodiesterase activity was located in both the membrane and the cytosol. In contrast to other microorganisms, B. japonicum adenylate cyclase remained firmly bound to the membrane during treatment with detergents. Adenylate cyclase was activated four- to fivefold by 0.01% sodium dodecyl sulfate (SDS), whereas other detergents gave only slight activation. SDS had no effect on the membrane-bound cAMP phosphodiesterase but strongly inhibited the soluble enzyme, indicating that the two enzymes are different. All three enzymes were characterized by their kinetic constants, pH optima, and divalent metal ion requirements. With increasing nodule age, adenylate cyclase activity increased, the membrane-bound cAMP phosphodiesterase decreased, and the soluble cAMP phosphodiesterase remained largely unchanged. These results suggest that cAMP plays a role in symbiosis.
已在慢生根瘤菌3I1b - 143的类菌体中鉴定出腺苷酸环化酶和环磷酸腺苷（cAMP）磷酸二酯酶，并对其进行了部分特性描述。腺苷酸环化酶活性存在于类菌体膜部分，而cAMP磷酸二酯酶活性则同时存在于膜和胞质溶胶中。与其他微生物不同，慢生根瘤菌的腺苷酸环化酶在用去污剂处理期间仍牢固地结合在膜上。0.01%的十二烷基硫酸钠（SDS）可使腺苷酸环化酶的活性提高4至5倍，而其他去污剂仅产生轻微激活作用。SDS对膜结合的cAMP磷酸二酯酶没有影响，但强烈抑制可溶性酶，表明这两种酶是不同的。所有这三种酶都通过其动力学常数、最适pH值和二价金属离子需求进行了特性描述。随着根瘤年龄的增加，腺苷酸环化酶活性增加，膜结合的cAMP磷酸二酯酶活性降低，而可溶性cAMP磷酸二酯酶基本保持不变。这些结果表明cAMP在共生中发挥作用。
