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


CONCLUSIONS
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.
Schwaiger
Rita
R
Max Planck Institute of Biochemistry, Department of Membrane Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
Schwarz
Christoph
C
Furtwängler
Katarina
K
Tarasov
Valery
V
Wende
Andy
A
Oesterhelt
Dieter
D
D001219:Aspartate Aminotransferases / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D020869:Gene Expression Profiling; D019848:Gene Expression Regulation, Archaeal; D019617:Halobacterium salinarum / Q000235:genetics* / Q000378:metabolism; D051756:Leucine-Responsive Regulatory Protein / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D046228:Microarray Analysis; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D014158:Transcription, Genetic
D051756:Leucine-Responsive Regulatory Protein; D001219:Aspartate Aminotransferases