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Open Access Highly Accessed Research article

Transcriptional control by two leucine-responsive regulatory proteins in Halobacterium salinarum R1

Rita Schwaiger1, Christoph Schwarz2, Katarina Furtwängler1, Valery Tarasov1, Andy Wende3 and Dieter Oesterhelt1*

Author Affiliations

1 Max Planck Institute of Biochemistry, Department of Membrane Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany

2 School of Life Sciences, Arizona State University, Tempe, Arizona 85287, USA

3 QIAGEN GmbH, Qiagen Strasse 1, 40724 Hilden, Germany

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BMC Molecular Biology 2010, 11:40  doi:10.1186/1471-2199-11-40

Published: 28 May 2010

Abstract

Background

Archaea combine bacterial-as well as eukaryotic-like features to regulate cellular processes. Halobacterium salinarum R1 encodes eight leucine-responsive regulatory protein (Lrp)-homologues. The function of two of them, Irp (OE3923F) and lrpA1 (OE2621R), were analyzed by gene deletion and overexpression, including genome scale impacts using microarrays.

Results

It was shown that Lrp affects the transcription of multiple target genes, including those encoding enzymes involved in amino acid synthesis, central metabolism, transport processes and other regulators of transcription. In contrast, LrpA1 regulates transcription in a more specific manner. The aspB3 gene, coding for an aspartate transaminase, was repressed by LrpA1 in the presence of L-aspartate. Analytical DNA-affinity chromatography was adapted to high salt, and demonstrated binding of LrpA1 to its own promoter, as well as L-aspartate dependent binding to the aspB3 promoter.

Conclusion

The gene expression profiles of two archaeal Lrp-homologues report in detail their role in H. salinarum R1. LrpA1 and Lrp show similar functions to those already described in bacteria, but in addition they play a key role in regulatory networks, such as controlling the transcription of other regulators. In a more detailed analysis ligand dependent binding of LrpA1 was demonstrated to its target gene aspB3.