Change search
ReferencesLink to record
Permanent link

Direct link
Reduced activity of glutamine synthetase in Rhodospirillum rubrum mutants lacking adenylyltransferase, GlnE
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Manuscript (Other academic)
URN: urn:nbn:se:su:diva-24454OAI: diva2:197554
Part of urn:nbn:se:su:diva-7050Available from: 2007-09-10 Created: 2007-09-03 Last updated: 2010-01-13Bibliographically approved
In thesis
1. Regulation of Glutamine Synthetase in the Diazotroph Rhodospirillum rubrum
Open this publication in new window or tab >>Regulation of Glutamine Synthetase in the Diazotroph Rhodospirillum rubrum
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The bacterial cell needs ammonia for synthesis of glutamine from glutamate. Only one enzyme is able to catalyze this reaction, namely glutamine synthetase (GS). GS can be regulated both transcriptionally and post-translationally and it is present in all kingdoms of life. Our study has been focused on the post-translational regulation of GS in the diazotrophic bacterium Rhodospirillum rubrum. A number of proteins are involved in the covalent regulation of GS, among them are the regulatory PII proteins that depending on growth conditions also like GS are covalently modified. We have purified all proteins involved in GS regulation and developed several in vitro assays with the aim of understanding GS regulation in R. rubrum. Studies on the influence of the small metabolite effectors α-ketoglutarate and glutamine are also included together with the effect of divalent cations.

In both R. rubrum and Escherichia coli, one of the enzymes participating in GS regulation is the bifunctional enzyme GlnE. GlnE is responsible for both the attachment and the removal of AMP groups from GS, which basically leads to a more inactive or active enzyme respectively. Apart from examining the above functions of GlnE, we have also found a novel third activity of R. rubrum GlnE, an antioxidant function, which is located in the C-terminal domain. We have examined this novel activity of GlnE in great detail, including site specific mutagenesis.

We also generated and analyzed ΔglnE mutants in R. rubrum and the results from these studies show that suppressor mutations can occur within glnA, the gene encoding GS. We assume that the function of these suppressor mutations is to lower the specific activity of GS, which otherwise might be too high in a ΔglnE mutant since they lack the ability to adenylylate GS. In other words, it seems that ΔglnE mutants can not be generated without producing suppressor mutations.

Place, publisher, year, edition, pages
Stockholm: Institutionen för biokemi och biofysik, 2007. 63 p.
glutamine synthetase, Rhodospirillum rubrum, GlnE, PII
National Category
Biochemistry and Molecular Biology
Research subject
urn:nbn:se:su:diva-7050 (URN)978-91-7155-495-6 (ISBN)
Public defence
2007-10-01, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 12 A, Stockholm, 14:00 (English)
Available from: 2007-09-10 Created: 2007-09-03 Last updated: 2010-01-12Bibliographically approved

Open Access in DiVA

No full text

By organisation
Department of Biochemistry and Biophysics

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 14 hits
ReferencesLink to record
Permanent link

Direct link