한빛사논문
- 조회4,891
Abstract
( leucine toxicity | nitrogen-metabolic phosphotransferase system (PTS) | potassium transporter TrkA | protein-protein interaction | signal transduction )
Chang-Ro Lee *, Seung-Hyon Cho *, Mi-Jeong Yoon *, Alan Peterkofsky †, and Yeong-Jae Seok *,‡
*Laboratory of Macromolecular Interactions, Department of Biological Sciences and Institute of Microbiology, Seoul National University, Seoul 151-742, Korea; and †Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
Edited by Rowena G. Matthews, University of Michigan, Ann Arbor, MI, and approved December 13, 2006 (received for review November 8, 2006)
The maintenance of ionic homeostasis in response to changes in the environment is essential for all living cells. Although there are still many important questions concerning the role of the major monovalent cation K+, cytoplasmic K+ in bacteria is required for diverse processes. Here, we show that enzyme IIANtr (EIIANtr) of the nitrogen-metabolic phosphotransferase system interacts with and regulates the Escherichia coli K+ transporter TrkA. Previously we reported that an E. coli K-12 mutant in the ptsN gene encoding EIIANtr was extremely sensitive to growth inhibition by leucine or leucine-containing peptides (LCPs). This sensitivity was due to the requirement of the dephosphorylated form of EIIANtr for the derepression of ilvBN expression. Whereas the ptsN mutant is extremely sensitive to LCPs, a ptsN trkA double mutant is as resistant as WT. Furthermore, the sensitivity of the ptsN mutant to LCPs decreases as the K+ level in culture media is lowered. We demonstrate that dephosphorylated EIIANtr, but not its phosphorylated form, forms a tight complex with TrkA that inhibits the accumulation of high intracellular concentrations of K+. High cellular K+ levels in a ptsN mutant promote the sensitivity of E. coli K-12 to leucine or LCPs by inhibiting both the expression of ilvBN and the activity of its gene products. Here, we delineate the similarity of regulatory mechanisms for the paralogous carbon and nitrogen phosphotransferase systems. Dephosphorylated EIIAGlc regulates a variety of transport systems for carbon sources, whereas dephosphorylated EIIANtr regulates the transport system for K+, which has global effects related to nitrogen metabolism.
Author contributions: C.-R.L., M.-J.Y., A.P., and Y.-J.S. designed research; C.-R.L., S.-H.C., and Y.-J.S. performed research; C.-R.L., S.-H.C., and M.-J.Y. contributed new reagents/analytic tools; C.-R.L., S.-H.C., A.P., and Y.-J.S. analyzed data; and C.-R.L., A.P., and Y.-J.S. wrote the paper.
The authors declare no conflict of interest.
Freely available online through the PNAS open access option.
‡To whom correspondence should be addressed.
논문정보
- Research article
- 2007년 02월 (BRIC 등록일 )
- 국내(교신)+국외 연구진
- 생명과학 > 미생물학
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