Gibson J L, Falcone D L, Tabita F R
Department of Microbiology, Ohio State University, Columbus 43210.
J Biol Chem. 1991 Aug 5;266(22):14646-53.
In Rhodobacter sphaeroides, many of the structural genes encoding enzymes of the Calvin cycle are duplicated and grouped within two separate clusters. In this study, the nucleotide sequence of a 5627-base pair region of DNA that contains the form I Calvin cycle gene cluster has been determined. The five open reading frames are arranged in the order, fbpA prkA cfxA rbcL rbcS and are tightly linked and oriented in the same direction. The results of insertional mutagenesis studies suggest the genes are organized within an operon. Consistent with this proposal, the cfxA gene has been tentatively identified as a gene encoding the Calvin cycle enzyme, aldolase. Measurement of the activities of various Calvin cycle enzymes in the insertion mutants showed that inactivation of genes within one CO2 fixation cluster affected expression of genes within the second cluster, revealing a complex regulatory network.
在球形红细菌中，许多编码卡尔文循环酶的结构基因是重复的，并被分成两个独立的簇。在本研究中，已确定了包含I型卡尔文循环基因簇的一段5627个碱基对的DNA区域的核苷酸序列。五个开放阅读框按fbpA、prkA、cfxA、rbcL、rbcS的顺序排列，紧密相连且方向相同。插入诱变研究结果表明这些基因是在一个操纵子内组织的。与此提议一致，cfxA基因已被初步鉴定为编码卡尔文循环酶醛缩酶的基因。对插入突变体中各种卡尔文循环酶活性的测量表明，一个二氧化碳固定簇内基因的失活会影响第二个簇内基因的表达，揭示了一个复杂的调控网络。
