MS FOR PROBING RESISTANCE STRATEGIES IN ACETIC ACID BACTERIA

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 细菌通过特殊的应激反应和细胞成分的化学变化来应对恶劣环境中的生命。我们探索了一种自然耐酸细菌乙酸杆菌在低pH值下生存的生化策略，它具有处理低pH值的能力--它的细胞质pH可以降到4--，特别是醋酸。这种革兰氏阴性的植物伴生菌已经在醋的生产中被使用了数千年。在低pH值下，醋酸对细菌的毒性特别大，因为它形成的二聚体很容易渗透到细胞膜。 Kappock解决这个问题的方法是以低pH值下的酶功能为中心，辅之以几个正在进行的基因组测序项目。我们发现，单个醋酸杆菌酶在酸性环境中保持功能的时间比非嗜酸生物的可比形式长得多。X射线结晶学揭示了醋酸菌蛋白质的独特结构特征，这可能赋予这种稳定性。我们还描述了高耐药菌株消除醋酸的代谢策略，这可能被包括几种病原体在内的其他微生物所利用。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Bacteria cope with life in harsh environments using specific stress responses and chemical alterations of cell components. We explore the biochemical strategies for survival at low pH employed by a naturally acid-resistant bacterium, Acetobacter aceti, which has the ability to handle low pH in general -- its cytoplasmic pH can drop as low as 4 -- and acetic acid in particular. This Gram-negative, plant-associated bacterium has been used for millenia in the production of vinegar. Acetic acid is especially toxic to bacteria at low pH because it forms dimers that easily permeate cell membranes. Kappock's approach to this problem is centered on enzyme function at low pH, assisted by several in-progress genome sequencing projects. We found that individual A. aceti enzymes retain function in acid much longer than comparable forms from non-acidophilic organisms. X-ray crystallography has revealed distinctive architectural features of A. aceti proteins that may confer this stability. We have also delineated metabolic strategies for acetic acid elimination by highly-resistant strains, which may be employed by other microbes including several pathogens.