Prokaryotic gene regulation by light and oxygen

氧张力的改变影响所有细胞类型中的基因表达。在细菌系统中，氧气调节 各种基因参与有氧和无氧能量代谢。代谢过程，如 碳固定、氮固定、呼吸作用和光合作用响应于存在而被调节。 或者没有氧气。在酵母和藻类细胞中，已知氧影响氧化防御的转录 基因以及代谢酶。在哺乳动物细胞中，已知越来越多的基因是 氧调节因子，如血管生长因子，它们是合成新毛细血管的关键调节因子。 从原有的血管中长出除了生理作用外，这些生长因子还参与疾病 例如在肿瘤生长期间刺激毛细血管形成的过程。 该提案的重点是阐明细菌荚膜红杆菌和 球形红细菌能够感知氧张力的变化，并作为响应，改变基因 表情这些相关物种能够以各种能量产生模式生长，包括 有氧呼吸、厌氧发酵和光合作用。参与每一个基因的表达 这些过程的变化受到氧张力的变化以及光强度的变化的影响。 还已知光对细胞生理的调节发生在许多生物体中， 哺乳动物，这是第二个过程，这是研究这个建议。事实上，氧气的关键之一 本研究中所研究的调控转录因子也受光照强度的调控。 作为研究氧和光对基因表达调控的模型系统，我们重点研究了 四吡咯生物合成的过程。该途径受氧气和光强度的高度调节， 它负责产生B12、血红素和叶绿素等重要代谢物。

Alteration in oxygen tension affects gene expression in all cell types. In bacterial systems, oxygen regulates a variety of genes involved in aerobic versus anaerobic energy metabolism. Metabolic processes such as carbon fixation, nitrogen fixation, respiration and photosynthesis are regulated in response to the presence or absence of oxygen. In yeast and algal cells, oxygen is known to affect transcription of oxidative defense genes as well as metabolic enzymes. In mammalian cells, a growing number of genes are known to be oxygen regulated such as vascular growth factors that are key regulators for the synthesis of new capillary sprouts from preexisting vessels. Besides physiological roles, these growth factors are involved in disease processes such as the stimulation of capillary formation during tumor growth. This proposal is centered on elucidating molecular details of how bacteria Rhodobacter capsulatus and Rhodobacter sphaeroides are able to sense changes in oxygen tension, and in response, alter gene expression. These related species are capable of growth in a variety of energy generating modes including aerobic respiration, anaerobic fermentation and photosynthesis. The expression of genes involved in each of these processes are affected by alterations in oxygen tension, as well as by variations in light intensity. Regulation of cell physiology by light is also known to occur in a number of organisms ranging from bacterial to mammals and is a second process that is studied by this proposal. Indeed, one of the key oxygen regulated transcription factors studied in this proposal is also regulated by light intensity. As a model system for studying both oxygen and light regulation of gene expression, we have focused on the process of tetrapyrrole biosynthesis. This pathway is highly regulated by oxygen and light intensity and is responsible for the production of such important metabolites as B12, heme and chlorophylls.