期刊
JOURNAL OF BACTERIOLOGY
卷 186, 期 13, 页码 4238-4245出版社
AMER SOC MICROBIOLOGY
DOI: 10.1128/JB.186.13.4238-4245.2004
关键词
-
类别
资金
- NIGMS NIH HHS [GM22323] Funding Source: Medline
Mutants of Escherichia coli lacking all of the known saturable K+ transport systems, triple mutants, require elevated K+ concentrations for growth. K+ transport activity in such mutants, called TrkF activity, has low substrate specificity and a low rate that increases with increasing external pH. Attempts to isolate mutants requiring even higher concentrations of K+ failed, implying that either TrkF is essential or is composed of multiple minor K+ transport activities. Instead, we sought mutations that allowed triple mutants to grow at lower K+ concentrations. Mutations so identified include ones altering MscL, the large mechanosensitive channel, or Opp, the oligopeptide permease. However, a possible contribution of wild-type Opp and MscL to TrkF activity was not proven. In contrast, expression of wild-type ProP, TrkG, and TrkH proteins increased uptake when encoded on multicopy plasmids. In all of these situations, the driving force for K+ appeared to be the transmembrane electric potential, and in most cases substrate specificity was low; these are characteristics of TrkF activity. These results support the view that TrkF is composed of multiple, aberrant K+ transport activities, i.e., paths that, regardless of their physiological function, allow K+ to cross the cell membrane by a uniport process.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据