Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The key to the lock that controls nitrogen fixation

04.11.2004


“Bacteria that fix nitrogen only do so when they sense that there is very little nitrogen available in their environment,” says Professor Ray Dixon (Project Leader at the JIC. “Normally the genes for nitrogen fixation are locked off and only unlocked and used when nitrogen levels in the environment fall. We have discovered a key piece of biochemistry that allows us to better understand how the lock operates and so may allow us to alter how it works”.

The bacterium Azotobacter vinelandii is able to fix atmospheric nitrogen when available nitrogen in its environment falls below a threshold level. Nitrogen fixation requires a great deal of energy and so the genes that carry out nitrogen fixation (so called nif genes) are tightly regulated and switched off when not required.

The nif genes are regulated by the action of two proteins, called NifL and NifA. NifA stimulates the activity of nif genes, while NifL normally binds to NifA and renders it inactive. Thus whether the nif genes are active or not depends on the interaction between these two proteins. Both proteins are sensitive to biochemical signals that occur in the bacterial cell when conditions are right for nitrogen fixation. The proteins’ physical shape and structure alters in response to these signals and this affects their ability to bind to one another. The result is that, when conditions are right for nitrogen fixation, NifA is released from the grip of NifL and is then able to stimulate the activity of the nif genes and so switches on nitrogen fixation by the cell.



The latest research has identified a single amino acid change in the NifL protein that prevents the molecule releasing NifA when the appropriate signals are present [2]. This gives the scientists an important clue about the key processes which operate the lock that controls nitrogen fixation.

The discovery will be reported in the international science journal Proceedings of the National Academy of Sciences US, and is available on line in the PNAS Online Early Edition [3].

[1]
The John Innes Centre (JIC), Norwich, UK is an independent, world-leading research centre in plant and microbial sciences. The JIC has over 850 staff and students. JIC carries out high quality fundamental, strategic and applied research to understand how plants and microbes work at the molecular, cellular and genetic levels. The JIC also trains scientists and students, collaborates with many other research laboratories and communicates its science to end-users and the general public. The JIC is grant-aided by the Biotechnology and Biological Sciences Research Council.

[2]
NifA is a sigma factor dependent transcriptional activator that stimulate nif gene activity. Its action is blocked by protein-protein binding with NifL, an anti-activator. NifL is sensitive to the redox and fixed nitrogen status of the cell. Binding of 2-oxoglutarate (an indicator of cell carbon status) to NifA prevents NifL from inhibiting NifA . A critical arginine residue (R306) has been identified in NifL that is required to release NifA under appropriate environmental conditions. Mutation of this residue blocks release of NifA from NifL. The substitution of this arginine significantly alters the conformation of the NifL molecule and inhibits NifA’s response to 2-oxoglutarate. It appears that arginine 306 is critical for coupling the response of NifL to the cellular redox and fixed nitrogen status to a conformational switch that prevents NifL from inhibiting NifA under conditions suitable for nitrogen fixation.

[3]
A crucial arginine residue is required for a conformational switch in NifL to regulate nitrogen fixation in Azotobacter vinelandii. I. Martinez-Argudo, R. Little and R. Dixon. Article #04-05312

Ray Mathias | alfa
Further information:
http://www.bbsrc.ac.uk
http://www.jic.ac.uk

More articles from Life Sciences:

nachricht Complementing conventional antibiotics
24.05.2018 | Goethe-Universität Frankfurt am Main

nachricht Building a brain, cell by cell: Researchers make a mini neuron network (of two)
23.05.2018 | Institute of Industrial Science, The University of Tokyo

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Surgery involving ultrasound energy found to treat high blood pressure

24.05.2018 | Medical Engineering

First chip-scale broadband optical system that can sense molecules in the mid-IR

24.05.2018 | Physics and Astronomy

Beyond the limits of conventional electronics: stable organic molecular nanowires

24.05.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>