Prokaryotic gene regulation by light and oxygen

氧分压的改变会影响所有类型细胞的基因表达。在细菌系统中，氧气调节 参与有氧和无氧能量代谢的各种基因。代谢过程，如 碳素固定、氮素固定、呼吸作用和光合作用都受到调节，以响应植物的存在 或者是缺氧。在酵母和藻类细胞中，已知氧气影响氧化防御的转录。 基因和新陈代谢酶。在哺乳动物细胞中，越来越多的基因被认为是 氧调节，如血管生长因子，是合成新毛细血管的关键调节因子 从先前存在的维管束中发出的嫩芽。除了生理作用，这些生长因子也与疾病有关。 在肿瘤生长过程中刺激毛细血管形成等过程。 这项建议的核心是阐明细菌的分子细节如何胶囊红杆菌和 球形红杆菌能够感知氧分压的变化，并相应地改变基因 表情。这些相关物种能够以各种能源产生模式生长，包括 好氧呼吸、厌氧发酵和光合作用。每一个相关基因的表达 在这些过程中，氧气压力的变化以及光强度的变化都会影响这些过程。 光对细胞生理的调节也已知发生在许多生物体中，从细菌 对哺乳动物来说，这是这一提议研究的第二个过程。事实上，氧气的关键之一 本研究中研究的受调控转录因子也受光照强度的调节。 作为一个研究氧和光对基因表达调控的模型系统，我们专注于 四吡咯的生物合成过程。这一途径受到氧和光强度的高度调节， 负责B12、血红素和叶绿素等重要代谢物的产生。

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.