Quantitative Kinetic Analyses of Shutting Off a Two-Component System
Cells rely on accurate control of signaling systems to adapt to environmental perturbations. System deactivation upon stimulus removal is as important as activation of signaling pathways. The two-component system (TCS) is one of the major bacterial signaling schemes. In many TCSs, phosphatase activi...
Main Authors: | , , |
---|---|
Format: | Article |
Language: | English |
Published: |
American Society for Microbiology
2017-05-01
|
Series: | mBio |
Online Access: | http://mbio.asm.org/cgi/content/full/8/3/e00412-17 |
id |
doaj-1b01e297b3e14860be0571b192635472 |
---|---|
record_format |
Article |
spelling |
doaj-1b01e297b3e14860be0571b1926354722021-07-02T01:39:32ZengAmerican Society for MicrobiologymBio2150-75112017-05-0183e00412-1710.1128/mBio.00412-17Quantitative Kinetic Analyses of Shutting Off a Two-Component SystemRong GaoAnn M. StockCaroline S. HarwoodCells rely on accurate control of signaling systems to adapt to environmental perturbations. System deactivation upon stimulus removal is as important as activation of signaling pathways. The two-component system (TCS) is one of the major bacterial signaling schemes. In many TCSs, phosphatase activity of the histidine kinase (HK) is believed to play an essential role in shutting off the pathway and resetting the system to the prestimulus state. Two basic challenges are to understand the dynamic behavior of system deactivation and to quantitatively evaluate the role of phosphatase activity under natural cellular conditions. Here we report a kinetic analysis of the response to shutting off the archetype Escherichia coli PhoR-PhoB TCS pathway using both transcription reporter assays and in vivo phosphorylation analyses. Upon removal of the stimulus, the pathway is shut off by rapid dephosphorylation of the PhoB response regulator (RR) while PhoB-regulated gene products gradually reset to prestimulus levels through growth dilution. We developed an approach combining experimentation and modeling to assess in vivo kinetic parameters of the phosphatase activity with kinetic data from multiple phosphatase-diminished mutants. This enabled an estimation of the PhoR phosphatase activity in vivo, which is much stronger than the phosphatase activity of PhoR cytoplasmic domains analyzed in vitro. We quantitatively modeled how strong the phosphatase activity needs to be to suppress nonspecific phosphorylation in TCSs and discovered that strong phosphatase activity of PhoR is required for cross-phosphorylation suppression.http://mbio.asm.org/cgi/content/full/8/3/e00412-17 |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Rong Gao Ann M. Stock Caroline S. Harwood |
spellingShingle |
Rong Gao Ann M. Stock Caroline S. Harwood Quantitative Kinetic Analyses of Shutting Off a Two-Component System mBio |
author_facet |
Rong Gao Ann M. Stock Caroline S. Harwood |
author_sort |
Rong Gao |
title |
Quantitative Kinetic Analyses of Shutting Off a Two-Component System |
title_short |
Quantitative Kinetic Analyses of Shutting Off a Two-Component System |
title_full |
Quantitative Kinetic Analyses of Shutting Off a Two-Component System |
title_fullStr |
Quantitative Kinetic Analyses of Shutting Off a Two-Component System |
title_full_unstemmed |
Quantitative Kinetic Analyses of Shutting Off a Two-Component System |
title_sort |
quantitative kinetic analyses of shutting off a two-component system |
publisher |
American Society for Microbiology |
series |
mBio |
issn |
2150-7511 |
publishDate |
2017-05-01 |
description |
Cells rely on accurate control of signaling systems to adapt to environmental perturbations. System deactivation upon stimulus removal is as important as activation of signaling pathways. The two-component system (TCS) is one of the major bacterial signaling schemes. In many TCSs, phosphatase activity of the histidine kinase (HK) is believed to play an essential role in shutting off the pathway and resetting the system to the prestimulus state. Two basic challenges are to understand the dynamic behavior of system deactivation and to quantitatively evaluate the role of phosphatase activity under natural cellular conditions. Here we report a kinetic analysis of the response to shutting off the archetype Escherichia coli PhoR-PhoB TCS pathway using both transcription reporter assays and in vivo phosphorylation analyses. Upon removal of the stimulus, the pathway is shut off by rapid dephosphorylation of the PhoB response regulator (RR) while PhoB-regulated gene products gradually reset to prestimulus levels through growth dilution. We developed an approach combining experimentation and modeling to assess in vivo kinetic parameters of the phosphatase activity with kinetic data from multiple phosphatase-diminished mutants. This enabled an estimation of the PhoR phosphatase activity in vivo, which is much stronger than the phosphatase activity of PhoR cytoplasmic domains analyzed in vitro. We quantitatively modeled how strong the phosphatase activity needs to be to suppress nonspecific phosphorylation in TCSs and discovered that strong phosphatase activity of PhoR is required for cross-phosphorylation suppression. |
url |
http://mbio.asm.org/cgi/content/full/8/3/e00412-17 |
work_keys_str_mv |
AT ronggao quantitativekineticanalysesofshuttingoffatwocomponentsystem AT annmstock quantitativekineticanalysesofshuttingoffatwocomponentsystem AT carolinesharwood quantitativekineticanalysesofshuttingoffatwocomponentsystem |
_version_ |
1721344589188562944 |