Phosphorylation/dephosphorylation of the receiver module at the conserved aspartate residue controls transphosphorylation activity of histidine kinase in sensor protein ArcB of Escherichia coli.

ABSTRACT GlnD is a bifunctional uridylyltransferase/uridylyl-removing enzyme (UTase/UR) and is believed to be the primary sensor of nitrogen status in the cell by sensing the level of glutamine in enteric bacteria. It plays an important role in nitrogen assimilation and metabolism by reversibly regulating the modification of PII protein; PII in turn regulates a variety of other proteins. GlnD appears to have four distinct domains: an N-terminal nucleotidyltransferase (NT) domain; a central HD domain, named after conserved histidine and aspartate residues; and two C-terminal ACT domains, named after three of the allosterically regulated enzymes in which this domain is found. Here we report the functional analysis of these domains of GlnD from Escherichia coli and Rhodospirillum rubrum. We confirm the assignment of UTase activity to the NT domain and show that the UR activity is a property specifically of the HD domain: substitutions in this domain eliminated UR activity, and a truncated protein lacking the NT domain displayed UR activity. The deletion of C-terminal ACT domains had little effect on UR activity itself but eliminated the ability of glutamine to stimulate that activity, suggesting a role for glutamine sensing by these domains. The deletion of C-terminal ACT domains also dramatically decreased UTase activity under all conditions tested, but some of these effects are due to the competition of UTase activity with unregulated UR activity in these variants.

Download Full-text

Escherichia coli TehB RequiresS-Adenosylmethionine as a Cofactor To Mediate Tellurite Resistance

Journal of Bacteriology ◽

10.1128/jb.182.22.6509-6513.2000 ◽

2000 ◽

Vol 182 (22) ◽

pp. 6509-6513 ◽

Cited By ~ 29

Author(s):

Mingfu Liu ◽

Raymond J. Turner ◽

Tara L. Winstone ◽

Andrea Saetre ◽

Melanie Dyllick-Brenzinger ◽

...

Keyword(s):

Escherichia Coli ◽

Nucleic Acid ◽

Conformational Changes ◽

Hydrodynamic Radius ◽

Multicopy Plasmid ◽

Cytoplasmic Protein ◽

Wild Type ◽

Methyltransferase Activity ◽

Tellurite Resistance ◽

Aspartate Residue

ABSTRACT The Escherichia coli chromosomal determinant for tellurite resistance consists of two genes (tehA andtehB) which, when expressed on a multicopy plasmid, confer resistance to K2TeO3 at 128 μg/ml, compared to the MIC of 2 μg/ml for the wild type. TehB is a cytoplasmic protein which possesses three conserved motifs (I, II, and III) found in S-adenosyl-l-methionine (SAM)-dependent non-nucleic acid methyltransferases. Replacement of the conserved aspartate residue in motif I by asparagine or alanine, or of the conserved phenylalanine in motif II by tyrosine or alanine, decreased resistance to background levels. Our results are consistent with motifs I and II in TehB being involved in SAM binding. Additionally, conformational changes in TehB are observed upon binding of both tellurite and SAM. The hydrodynamic radius of TehB measured by dynamic light scattering showed a ∼20% decrease upon binding of both tellurite and SAM. These data suggest that TehB utilizes a methyltransferase activity in the detoxification of tellurite.

Download Full-text

A histidine kinase sensor protein gene is necessary for induction of low pH tolerance in Sinorhizobium sp. strain BL3

Antonie van Leeuwenhoek ◽

10.1007/s10482-005-9015-0 ◽

2005 ◽

Vol 89 (1) ◽

pp. 125-134 ◽

Cited By ~ 2

Author(s):

Panlada Tittabutr ◽

Waraporn Payakapong ◽

Neung Teaumroong ◽

Nantakorn Boonkerd ◽

Paul W. Singleton ◽

...

Keyword(s):

Histidine Kinase ◽

Protein Gene ◽

Low Ph ◽

Ph Tolerance ◽

Sensor Protein

Download Full-text

Fumarate Regulation of Gene Expression in Escherichia coli by the DcuSR (dcuSR Genes) Two-Component Regulatory System

Journal of Bacteriology ◽

10.1128/jb.180.20.5421-5425.1998 ◽

1998 ◽

Vol 180 (20) ◽

pp. 5421-5425 ◽

Cited By ~ 83

Author(s):

Evelyn Zientz ◽

Johannes Bongaerts ◽

Gottfried Unden

Keyword(s):

Escherichia Coli ◽

Histidine Kinase ◽

Response Regulator ◽

Regulation Of Gene Expression ◽

Regulatory System ◽

E Coli ◽

Expression In Escherichia Coli ◽

Two Component ◽

Genes Encoding ◽

Periplasmic Domain

ABSTRACT In Escherichia coli the genes encoding the anaerobic fumarate respiratory system are transcriptionally regulated by C4-dicarboxylates. The regulation is effected by a two-component regulatory system, DcuSR, consisting of a sensory histidine kinase (DcuS) and a response regulator (DcuR). DcuS and DcuR are encoded by the dcuSR genes (previouslyyjdHG) at 93.7 min on the calculated E. coli map. Inactivation of the dcuR anddcuS genes caused the loss of C4-dicarboxylate-stimulated synthesis of fumarate reductase (frdABCD genes) and of the anaerobic fumarate-succinate antiporter DcuB (dcuB gene). DcuS is predicted to contain a large periplasmic domain as the supposed site for C4-dicarboxylate sensing. Regulation by DcuR and DcuS responded to the presence of the C4-dicarboxylates fumarate, succinate, malate, aspartate, tartrate, and maleate. Since maleate is not taken up by the bacteria under these conditions, the carboxylates presumably act from without. Genes of the aerobic C4-dicarboxylate pathway encoding succinate dehydrogenase (sdhCDAB) and the aerobic succinate carrier (dctA) are only marginally or negatively regulated by the DcuSR system. The CitAB two-component regulatory system, which is highly similar to DcuSR, had no effect on C4-dicarboxylate regulation of any of the genes.

Download Full-text