Electron Transfer in Extremely Halophilic Bacteria

高离子强度形式的环境应力 已经被一些生物体超越了 的方式 一般来说，人们对电子转移或 结合极端嗜盐生物的能量守恒。 在初步研究中，研究人员发现， 从蛋白质中观察到的电子转移机制 非嗜盐菌必须与极端的 嗜盐菌，因为静电似乎起着重要作用 在电子转移过程中。 因此，蛋白质在 中度和极端嗜盐菌的周质空间必须 控制特异性的因素， 静电学 此外，极端和中度嗜盐者 似乎具有氧化还原蛋白， 电位，是强酸性的，并且在至少两种情况下具有 氧化还原电位是离子强度依赖于在高 离子强度 由此看来，在 适应高离子强度环境，结构 在分子水平上发生了改变。 应当 需要强调的是，耐盐细菌，那些能够在 无论是加盐还是不加盐， 淡水细菌 三种嗜盐生物 用这笔钱学习。 可溶性氧化还原蛋白（c型细胞色素和铁硫蛋白 蛋白质）的特性， 离子强度和离子浓度调节剂的作用 氧化还原电位，光谱特性，和热 变性 数据将根据已知的 并辅以计算机建模 利用相关蛋白质的三维结构。 最后是一些 将研究基本的生理过程。 是 预计拟议的研究将提供新的 深入了解控制生物学的分子特性 电子转移，更好地理解生理学， 嗜盐菌，以及我们对结构的了解的增加， 和控制蛋白质稳定性的化学参数。

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.