A novel repressor of nif and glnA expression in the methanogenic archaeon Methanococcus maripaludis

63Citations
Citations of this article
36Readers
Mendeley users who have this article in their library.

This article is free to access.

Abstract

Nitrogen assimilation in the methanogenic archaeon Methanococcus maripaludis is regulated by transcriptional repression involving a palindromic 'nitrogen operator' repressor binding sequence. Here we report the isolation of the nitrogen repressor, NrpR, from M. maripaludis using DNA affinity purification. Deletion of the nrpR gene resulted in loss of nitrogen operator binding activity in cell extracts and loss of repression of nif (nitrogen-fixation) and glnA (glutamine synthetase) gene expression in vivo. Genetic complementation of the nrpR mutation restored all functions. NrpR contained a putative N-terminal winged helix-turn-helix motif followed by two mutually homologous domains of unknown function. Comparison of the migration of NrpR in gel-filtration chromatography with its subunit molecular weight (60 kDa) suggested that NrpR was a tetramer. Several lines of evidence suggested that the level of NrpR itself is not regulated, and the binding affinity of NrpR to the nitrogen operator is controlled by an unknown mechanism. Homologues of NrpR were found only in certain species in the kingdom Euryarchaeota. Full length homologues were found in Methanocaldococcus jannaschii and Methanothermobacter thermoautotrophicus, and homologues lacking one or more of the three polypeptide domains were found in Archaeoglobus fulgidus, Methanopyrus kandleri, Methanosarcina acetivorans, and Methanosarcina mazei. NrpR represents a new family of regulators unique to the Euryarchaeota.

Cite

CITATION STYLE

APA

Lie, T. J., & Leigh, J. A. (2003). A novel repressor of nif and glnA expression in the methanogenic archaeon Methanococcus maripaludis. Molecular Microbiology, 47(1), 235–246. https://doi.org/10.1046/j.1365-2958.2003.03293.x

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free