# Molecular Mechanisms of Signal Transduction by Two-Component Regulatory Systems

> **NIH NIH R01** · UNIV OF NORTH CAROLINA CHAPEL HILL · 2020 · $480,662

## Abstract

PROJECT SUMMARY
 The ability to respond to stimuli is often considered to be a key characteristic of life. Cells can detect new
conditions, transduce that information into a usable form, and execute an appropriate response. One common
signal transduction strategy is to represent information by the specific and transient placement of phosphoryl
groups on proteins. Errors in signal transduction can lead to diseases (e.g. cancer, diabetes), and drugs have
been developed to block aberrant signaling processes. Understanding the mechanisms, regulation, and impact
of protein phosphorylation is thus of fundamental interest, as well as of practical significance to human health.
 Microorganisms are the dominant form of life on Earth by many measures, including genetic diversity, raw
numbers, environmental distribution, and evolutionary experience. Thus, it is logical to seek basic signal
transduction principles in microbes. Our long-term goal is comprehensive understanding of signal transduction
by two-component regulatory systems, which occur in microorganisms from all three phylogenetic domains, as
well as plants. In a basic two-component system, a sensor kinase (SK) detects stimuli and autophosphorylates
using ATP. A response regulator (RR) then catalyzes phosphotransfer from the SK (or from small molecules),
which turns on the response. RR dephosphorylation, either self-catalyzed or stimulated by another protein,
ends the response. Inclusion of histidine-containing phosphotransferase (Hpt) proteins results in more
complex multi-step phosphorelays by adding an Hpt and a second RR onto the basic SK to RR scheme. The
kinetics and directionality of phosphoryl group reactions are important to synchronize responses with stimuli.
 Genome sequencing presents a challenge (a rapidly widening gap between the number of known proteins
and what can be studied experimentally) and an opportunity (diverse and extensive sequence data). To learn
how to reveal properties of hundreds of thousands of two-component proteins from sequence data alone, our
innovative research strategy focuses on amino acid sequence differences (rather than similarities) between the
conserved domains of SKs, Hpts, or RRs. Our well-established and productive experimental approach
integrates biochemistry, bioinformatics, biophysics, molecular biology, and structural biology. In this project,
we will identify factors that affect the kinetics of self-catalyzed RR phosphorylation and dephosphorylation (AIM
1), SK-stimulated dephosphorylation of RRs (AIM 2), and phosphotransfer reactions between Hpts and RRs
(AIM 3). We will also characterize the molecular mechanisms underlying each of these reactions.
 Antibiotic resistance of bacterial and fungal pathogens is a major and increasing threat to human health.
RRs are central to most phosphotransfer reactions of two-component systems. Our study of binding of small
molecules to RRs may influence design of therapeutic agents to disable critical two-compone...

## Key facts

- **NIH application ID:** 9906228
- **Project number:** 5R01GM050860-25
- **Recipient organization:** UNIV OF NORTH CAROLINA CHAPEL HILL
- **Principal Investigator:** Robert B. Bourret
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $480,662
- **Award type:** 5
- **Project period:** 1994-05-01 → 2022-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9906228

## Citation

> US National Institutes of Health, RePORTER application 9906228, Molecular Mechanisms of Signal Transduction by Two-Component Regulatory Systems (5R01GM050860-25). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/9906228. Licensed CC0.

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