Baker S C, Ferguson S J, Ludwig B, Page M D, Richter O M, van Spanning R J
Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom.
Microbiol Mol Biol Rev. 1998 Dec;62(4):1046-78. doi: 10.1128/MMBR.62.4.1046-1078.1998.
Paracoccus denitrificans and its near relative Paracoccus versutus (formerly known as Thiobacilllus versutus) have been attracting increasing attention because the aerobic respiratory system of P. denitrificans has long been regarded as a model for that of the mitochondrion, with which there are many components (e.g., cytochrome aa3 oxidase) in common. Members of the genus exhibit a great range of metabolic flexibility, particularly with respect to processes involving respiration. Prominent examples of flexibility are the use in denitrification of nitrate, nitrite, nitrous oxide, and nitric oxide as alternative electron acceptors to oxygen and the ability to use C1 compounds (e.g., methanol and methylamine) as electron donors to the respiratory chains. The proteins required for these respiratory processes are not constitutive, and the underlying complex regulatory systems that regulate their expression are beginning to be unraveled. There has been uncertainty about whether transcription in a member of the alpha-3 Proteobacteria such as P. denitrificans involves a conventional sigma70-type RNA polymerase, especially since canonical -35 and -10 DNA binding sites have not been readily identified. In this review, we argue that many genes, in particular those encoding constitutive proteins, may be under the control of a sigma70 RNA polymerase very closely related to that of Rhodobacter capsulatus. While the main focus is on the structure and regulation of genes coding for products involved in respiratory processes in Paracoccus, the current state of knowledge of the components of such respiratory pathways, and their biogenesis, is also reviewed.
脱氮副球菌及其近缘种维氏副球菌（以前称为维氏硫杆菌）一直备受关注，因为脱氮副球菌的有氧呼吸系统长期以来被视为线粒体有氧呼吸系统的模型，二者有许多共同的组分（如细胞色素aa3氧化酶）。该属成员表现出极大的代谢灵活性，特别是在涉及呼吸作用的过程方面。灵活性的突出例子包括在反硝化作用中使用硝酸盐、亚硝酸盐、一氧化二氮和一氧化氮作为替代氧的电子受体，以及利用C1化合物（如甲醇和甲胺）作为呼吸链的电子供体的能力。这些呼吸过程所需的蛋白质不是组成型的，调节其表达的潜在复杂调控系统也开始被揭示。对于α-3变形菌纲成员（如脱氮副球菌）中的转录是否涉及传统的σ70型RNA聚合酶一直存在不确定性，特别是因为尚未轻易鉴定出典型的-35和-10 DNA结合位点。在本综述中，我们认为许多基因，特别是那些编码组成型蛋白质的基因，可能受与荚膜红细菌的σ70 RNA聚合酶密切相关的σ70 RNA聚合酶的控制。虽然主要重点是脱氮副球菌中编码参与呼吸过程产物的基因的结构和调控，但也综述了此类呼吸途径的组分及其生物发生的当前知识状态。
