Molecular and General Genetics MGG

, Volume 263, Issue 1, pp 119–130

Thermostability, oligomerization and DNA-binding properties of the regulatory protein ArgR from the hyperthermophilic bacterium Thermotoga neapolitana

  • D. Dimova
  • P. Weigel
  • M. Takahashi
  • F. Marc
  • G. D. Van Duyne
  • V. Sakanyan
ORIGINAL PAPER

DOI: 10.1007/PL00008670

Cite this article as:
Dimova, D., Weigel, P., Takahashi, M. et al. Mol Gen Genet (2000) 263: 119. doi:10.1007/PL00008670

Abstract

The hexameric regulatory protein ArgR formed by arginine-mediated dimerization of identical trimers governs the expression of genes required for arginine metabolism and some other genes in mesophilic and moderately thermophilic bacteria. We have cloned the argR gene from two hyperthermophilic bacteria of the genus Thermotoga. The two-domain ArgR proteins encoded by T. neapolitana and T. maritima share a low degree of sequence similarity with other bacterial arginine repressors. The ArgR protein from T. neapolitana binds to an operator located just upstream of its coding sequence and, therefore, the argR gene may be autoregulated. The protein has extremely high intrinsic thermostability and tolerance to urea. Moreover, its binding to target DNA increases the melting temperature by approximately 15° C. The formation of oligomeric ArgR-DNA complexes is a function of protein concentration, with hexameric complexes being favoured at higher concentrations. In the presence of arginine the hyperthermophilic ArgR protein binds to its own operator, argRo, only by forming hexamer ArgR-DNA complexes, whereas both trimer-DNA and hexamer-DNA complexes are detected in the absence of arginine. However, the affinity of T. neapolitana ArgR for DNA has been found to be higher for a mixture of trimers and non-bound hexamers than for arginine-bound hexamers. Our data indicate that genes for arginine biosynthesis are clustered in a putative operon, which could also be regulated by the ArgR protein, in the hyperthermophilic host.

Key wordsThermotogaArgR proteinThermostabilityDNA bindingArginine

Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • D. Dimova
    • 1
  • P. Weigel
    • 1
  • M. Takahashi
    • 2
  • F. Marc
    • 1
  • G. D. Van Duyne
    • 3
  • V. Sakanyan
    • 1
  1. 1.Laboratoire de Biotechnologie, UPRES Biocatalyse, Faculté des Sciences et des Techniques, Université de Nantes, 44322 Nantes Cedex 3, France E-mail: Vehary.Sakanyan@svt.univ-nantes.fr, Tel.: +33-25-1125620, Fax: +33-25-1125612FR
  2. 2.Institut Curie, 91405 Orsay Cedex, FranceFR
  3. 3.Department of Biochemistry and Biophysics and Johnson Research Foundation, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USAUS