"LiT": Regulation of 5-Aminolevulinic Acid Biosynthesis in the Bacterium Rhodobacter sphaeroides

该奖项由2009年美国复苏和再投资法案(公法111-15)资助。智力价值四氢吡咯是所有生物体代谢所必需的生物分子。它们构成了在产生能量的电子转移反应中起作用的血红素部分的基础，也形成了叶绿素的核心，后者在光合作用中发挥着主要的捕光功能。因此，生命系统中的能量转换离不开四个吡咯的作用。这项拟议的研究调查了四吡咯生物合成的重要步骤，即前体分子5-氨基酮丙酸(ALA)的生物合成。两个丙氨酸合成酶基因HEMA和HEMT的活性和调节将在球形红细菌中进行研究，该细菌能够获得化学和光能，并能够固定碳和氮，所有这些过程都需要四个角色。利用不同的新陈代谢程序生长的能力使这种有机体能够最佳地利用环境资源，并不令人惊讶的是，它的新陈代谢受到对环境的精细调节。这项拟议的研究将研究HEMA和HEMT的调控，包括参与HEMT转录的新的Sigma因子SigT的作用。这两种不同的ALA合成酶的存在与生长条件有关的重要性将得到检验。实验涉及基本的细菌分子遗传学和生物化学。拟议的研究将为生物体如何利用遗传灵活性来适应不同的环境提供新的见解。此外，还将获得有关基因表达和新陈代谢调控的基本信息，这一途径无疑对地球上生命的进化至关重要。广泛影响球藻有氧生长和光合作用生长的颜色差异为特定基因调控提供了非常令人信服的证据。这些视觉上可以观察到的代谢变化对环境的反应继续激起学生的好奇心和兴趣。超过38名学生，其中绝大多数是女性，在实验室工作过，在那里他们第一手了解了为什么基础研究如此重要和有价值；几乎所有人都留在了科学领域，这让人们对拟议中的调查可能产生的更广泛结果毫不怀疑。对这项研究的支持将仍然是高质量课堂和实验室教学的基石；学生们自我报告说，熟悉最先进的科学使他们在研究生和专业课程中更具竞争力。ALA具有农业和医疗用途。多年来，由厌氧光营养生物经济地生产它一直是全世界感兴趣的问题。更清楚地了解其受调节的形成和所涉及的酶，以及这些细胞中的能量代谢，已经并将继续消除其生产改进的现有障碍。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-15).Intellectual meritTetrapyrroles are essential biomolecules required for metabolism in all organisms. They form the basis of heme moieties, which act in energy-generating electron transfer reactions, and they also form the core of chlorophylls, which perform the major light harvesting function in photosynthesis. Thus, tetrapyrroles are indispensable for energy transformations in living systems. The proposed research investigates an important step in tetrapyrrole biosynthesis, the biosynthesis of the precursor molecule 5-aminolevulinic acid (ALA). The activity and regulation of two ALA synthase genes, hemA and hemT will be studied in the bacterium Rhodobacter sphaeroides, which is capable of harvesting both chemical and light energy and can fix both carbon and nitrogen, all processes which require tetrapyrroles. The ability to grow using distinct metabolic programs allows this organism to optimally utilize environmental resources, and not surprisingly its metabolism is exquisitely regulated in response to the environment. The proposed research will investigate regulation of hemA and hemT, including the role of novel sigma factor SigT, which is involved in hemT transcription. The significance of the presence of these two different ALA synthases as they relate to growth conditions will be tested. Experiments involve basic bacterial molecular genetics and biochemistry. The proposed studies will provide new insights into how organisms use genetic flexibility to adapt to different environments. In addition, fundamental information will be gained about regulation of gene expression and metabolism of a pathway that no doubt has been critical to the evolution of life on earth.Broader ImpactsThe difference in color of R. sphaeroides growing aerobically vs. photosynthetically provides an extraordinarily convincing demonstration of specific gene regulation. These visually observable metabolic changes in response to the environment continue to pique the curiosity and interest students. Over 38 students, the vast majority of whom are women, have worked in the lab where they have learned first-hand why basic research is important and worthwhile; nearly all have remained in science, leaving no doubt of the broader outcomes that can emerge from the proposed investigations. Support for this research will remain a cornerstone to quality classroom and lab instruction; students have self-reported being acquainted with state-of-the-art science made them more competitive for graduate and professional programs. ALA has agricultural and medical uses. Its economical production by anoxygenic phototrophic organisms has been of interest throughout the world for many years. A clearer understanding of its regulated formation and the enzymes involved, as well as energy metabolism in these cells, has and will continue to remove existing impediments to improvements in its production.