# Prokaryotic gene regulation by light and oxygen

> **NIH NIH R01** · TRUSTEES OF INDIANA UNIVERSITY · 2020 · $383,683

## Abstract

Project Summary
All bacteria must alter their physiology in response to changes in their environment nn order to survive and
flourish. One important environmental cue that most species respond to is the presence or absence of
molecular oxygen. In most bacterial species, as well as in mitochondria in eukaryotes, oxygen is used
during the process of respiration as an energy generating terminal electron acceptor. In its absence, cells
must derive energy by alternative means such as fermentation that led to metabolic production of many
end products that are of economic importance. For example, fermentation can lead to the production of
such commercially important products as acids, alcohols, methane and H2.
 Even though the use of oxygen by cells is important for life as we know it, oxygen can also have
deleterious effects as it can readily form damaging oxygen reactive species such as singlet oxygen. Thus
cells must be capable of sensing the presence and absence of oxygen and subsequently alter their
metabolism to take advantage of its energy generating potential as well as to survive deleterious effects of
this reactive molecule. Often the sensing of oxygen by regulatory proteins is linked to the alteration of
cellular physiology by coupling an oxygen-sensing domain with a DNA binding domain that allows direct
gene expression control in response to the presence or absence of oxygen.
 In some photosynthetic species that use light as an alternative energy source, sensing oxygen is also
linked to sensing light intensity. In this case there are also a set of photoreceptors that absorb light that
subsequently alter gene expression in response to light intensity. This secondary light control is used to
ensure that there is proper balance of the generation of reducing power by photosynthesis (electrons) with
the utilization of reducing power by respiration that uses oxygen as an electron acceptor.
 In this proposal, we outline a study of the regulation of bacterial gene expression in response to
alterations in oxygen tension and light intensity in the model photosynthetic organism Rhodobacter
capsulatus. This organism has a large swing in cellular redox potential caused by the presence of light
driven energy production by a photosystem. In addition, these cells can also utilize oxygen and other
compounds for respiration. Consequently, this species has a large set of oxygen and light responding
transcription factors that are used to alter cellular physiology to promote growth in a variety of conditions
with and without the presence of oxygen and/or light. We describe biochemical and genetic studies that
will define how several regulatory proteins sense oxygen and light and how they subsequently alter cellular
gene expression and metabolism. The results to date show that many oxygen and light responding
transcription factors used by Rhodobacter capsulatus are also present in many non-photosynthetic species
including important pathogens.

## Key facts

- **NIH application ID:** 9888211
- **Project number:** 5R01GM040941-31
- **Recipient organization:** TRUSTEES OF INDIANA UNIVERSITY
- **Principal Investigator:** CARL Eugene BAUER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $383,683
- **Award type:** 5
- **Project period:** 1989-12-01 → 2022-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9888211

## Citation

> US National Institutes of Health, RePORTER application 9888211, Prokaryotic gene regulation by light and oxygen (5R01GM040941-31). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/9888211. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*