ACID/BASE PHYSIOLOGY OF ORAL STREPTOCOCCI

此应用程序是为了支持一个项目的重点是酸碱 菌斑细菌的生理学，尤其是变形链球菌，但 还有干酪乳杆菌和精氨酸脱亚胺酶阳性链球菌。 建议的工作源于以前的研究， 特别关注质子转运F-ATP酶。 一个基本 一种假说认为，牙菌斑中的耐酸细菌也越多， 更容易生龋。 要成为致龋菌，细菌必须能够在 菌斑，成为植物群的重要部分，并产生酸。 然而，由于对牙齿的挑战是指数相关的， 菌斑酸化的程度，那些可以降低 菌斑pH值低至0.4是特别有害的。 结果 我们先前的工作表明，F-ATP酶对酸的两种适应性 宽容 耐受性更强的生物体具有更高的F-ATPase活性， 单位的细胞重量，并且酶具有较低的活性最适pH。 计划将这些结果推广到其他生物，特别是 耐酸非突变菌空斑链球菌 拟议的工作将 现在考虑酶的质子转移效率， 耦合比即，每个ATP转运多少质子 水解，意味着抑制酶并影响酶的效率。 偶联，并可能参与乳酸转运质子 水流 从变形链球菌GS-5分离的膜囊泡 将被广泛用于拟议的工作，因为将细菌生长 在各种条件下的生物膜中。 此外，分离的基因 对S.变异体将被用于研究 F-ATP酶合成。 在牙菌斑的整个酸碱循环中， 精氨酸脱亚胺酶阳性细菌被认为是重要的 保护不太耐酸的细菌免受酸损害， 降低致龋性。 建议研究如何规管 精氨酸脱亚胺酶系统（ADS）的氧化还原电位。sanguis和S. 对ADS阴性突变体、在生物膜中生长的细胞和 精氨酸肽的跨膜转运。 我们之前的工作结果和其他人的工作结果表明存在重叠 在噬斑链球菌的抗酸适应中， 损伤和抗氧化损伤，例如， 氢过氧化物。 我们建议更详细地定义酸的性质 损害，特别是糖酵解系统，以及 酸损伤和氧化损伤。 一个主要目标是发展 意味着，例如，与氧化损伤增强剂，以减少酸 耐受性和致龋性。

This application is for support of a project focused on the acid-base physiology of plaque bacteria, especially the mutans streptococci, but also Lactobacillus casei and arginine-deiminase positive streptococci. The proposed work arises from previous studies the acid tolerance with particular attention on proton-translocating F-ATPases. A basic hypothesis is that the more acid-tolerant bacteria in plaque are also the more cariogenic. To be cariogenic, a bacterium must be able to colonize plaque, become a significant part of the flora, and produce acid. However, since the challenge to the tooth is exponentially related to the extent of acidification of plaque, those organisms which can lower the plaque pH to values as low as .4 are particularly damaging. The results of our prior work indicated two adaptations in F-ATPases for acid tolerance. More tolerant organisms have higher F-ATPase activities per unit of cell weight, and the enzymes have lower pH optima for activity. Plans are to extend these results with other organisms, especially the acid-tolerant, non-mutants, plaque streptococci. The proposed work will now consider proton-translocating efficiencies of the enzymes in terms of coupling ratios i.e., how many protons are transported per ATP hydrolyzed, means to inhibit the enzyme and to affect the efficiency of coupling, and the possible involvement of lactate transport in proton currents. Membrane vesicles isolated from Streptococcus mutans GS-5 will be used extensively for the proposed work, as will bacteria grown in biofilms under a variety of conditions. In addition, isolated genes for the atp operon of S. mutans will be used for studies of regulation of F-ATPase synthesis. In the overall acid-base cycles of plaque, ammonia production by arginine-deiminase-positive bacteria is considered important for protecting less acid-tolerant bacteria against acid damage and for reducing cariogenicity. Studies are proposed on regulation of the arginine deiminase system (ADS) by redox potential in S. sanguis and S. rattus, on ADS-negative mutants, on cells grown in biofilms and on transmembrane transport of arginine peptides. The results of our previous work and that of others has indicated overlap in the adaptations of plaque streptococci for protection against acid damage and against oxidative damage caused, for example, by hydroperoxides. We proposed to define in more detail the nature of acid damage, especially to the glycolytic system, and the relationship between acid damage and oxidative damage. A major objective will be to develop means, for example, with enhancers of oxidative damage, to reduce acid tolerance and cariogenicity.