Electron Transfer in Extremely Halophilic Bacteria

极嗜盐细菌中的电子转移

• 批准号: 8718678
• 负责人: Terrance Meyer
• 金额: $ 15.19万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-04-01 至 1991-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8718678&HistoricalAwards=false
• 关键词: Electron; Transfer; Extremely; Halophilic; Bacteria

Environmental stress in the form of high ionic strength has been surmounted by a number of organisms in a number of ways. In general, little is known about electron transfer or coupled energy conservation in any of the extreme halophiles. In preliminary studies, the investigator has found that electron transfer mechanisms observed with proteins from nonhalophilic bacteria must be distinct from the extreme halophiles, as electrostatics appear to play an important role in the elctron transfer proecss. Thus, proteins operating in the periplasmic space in moderate and extreme halophiles must control specificity by the use of factors other than electrostatics. In addition, extreme and moderate halophiles appear to have redox proteins which have generally lower redox potentials, are strongly acidic, and in at least two cases have redox potentials which are ionic strength-dependent at high ionic strengths. Thus it appears that in the course of adaptation to a high ionic strength environment, structural alterations at the molecular level have taken place. It should be emphasized that halotolerant bacteria, those able to live both with and without salt, are not obviously different from fresh-water bacteria. Three halophilic organisms will be studied with this grant. Soluble redox proteins (c-type cytochromes and iron-sulfur proteins) from these bacteria will be characterized in terms of location and the effect of osmoregulators and ionic strength on redox potentials, spectral properties, and thermal denaturation. Data will be analyzed in terms of known structural properties and supplemented by computer modeling utilizing 3-D structures of related proteins. Finally, some basic physiological processes will be studied. It is anticipated that the proposed studies will provide new insights into the molecular properties controlling biological electron transfer, a better understanding of the physiology of halophiles, and an increase in our knowledge of the structural and chemical parameters that control protein stability.

许多生物体已通过多种方式克服了高离子强度形式的环境压力。 一般来说，人们对极端嗜盐生物中的电子转移或耦合能量守恒知之甚少。 在初步研究中，研究人员发现，用非嗜盐细菌的蛋白质观察到的电子转移机制必须与极端嗜盐细菌不同，因为静电似乎在电子转移过程中发挥着重要作用。 因此，在中度和极端嗜盐生物的周质空间中起作用的蛋白质必须通过使用静电以外的因素来控制特异性。 此外，极端和中度嗜盐生物似乎具有通常具有较低氧化还原电势的氧化还原蛋白，呈强酸性，并且在至少两种情况下具有在高离子强度下依赖于离子强度的氧化还原电势。 由此看来，在适应高离子强度环境的过程中，发生了分子水平的结构改变。 应该强调的是，耐盐细菌能够在有盐和无盐的情况下生存，与淡水细菌没有明显区别。 这笔资助将研究三种嗜盐生物。 来自这些细菌的可溶性氧化还原蛋白（c 型细胞色素和铁硫蛋白）将根据位置以及渗透调节剂和离子强度对氧化还原电位、光谱特性和热变性的影响进行表征。 数据将根据已知的结构特性进行分析，并通过利用相关蛋白质的 3-D 结构的计算机建模进行补充。 最后，将研究一些基本的生理过程。 预计所提出的研究将为控制生物电子转移的分子特性提供新的见解，更好地了解嗜盐菌的生理学，并增加我们对控制蛋白质稳定性的结构和化学参数的了解。