Sensing of remote oxyanion binding at the DNA binding domain of the molybdate-dependent transcriptional regulator, ModE.

The molybdate-dependent transcriptional regulator ModE of Escherichia coli displays a large (50%) quenching of its intrinsic tryptophan fluorescence on binding molybdate. The changes in fluorescence have been exploited to analyse the binding of molybdate to ModE. Utilising site-directed mutagenesis, a series of phenylalanine substitutions for the three tryptophans of ModE (Trp49, Trp131 and Trp186) have been constructed, to yield three mono-Trp-containing derivatives.

Insight into the role of Escherichia coli MobB in molybdenum cofactor biosynthesis based on the high resolution crystal structure.

Two proteins, which are co-transcribed in Escherichia coli (MobA and MobB), are involved in the attachment of a nucleotide moiety to the molybdenum cofactor to form active molybdopterin guanine dinucleotide. Although not essential for this process, the dimeric MobB increases the activation of molybdoenzymes, incorporating this cofactor by a mechanism that is not understood. The structure of MobB has been elucidated in two crystal forms, one of which has provided a model at 1.

In vivo detection of molybdate-binding proteins using a competition assay with ModE in Escherichia coli.

Molybdenum is an important trace element as it forms the essential part of the active site in all molybdenum-containing enzymes. We have designed an assay for the in vivo detection of molybdate binding to proteins in Escherichia coli. The assay is based on (i).

Crystal structure of activated ModE reveals conformational changes involving both oxyanion and DNA-binding domains.

ModE is a bacterial transcriptional regulator that orchestrates many aspects of molybdenum metabolism by binding to specific DNA sequences in a molybdate-dependent fashion. We present the crystal structure of Escherichia coli ModE in complex with molybdate, which was determined at 2.75A from a merohedrally twinned crystal (twin fraction approximately 0.

Passive acquisition of ligand by the MopII molbindin from Clostridium pasteurianum: structures of apo and oxyanion-bound forms.

MopII from Clostridium pasteurianum is a molbindin family member. These proteins may serve as intracellular storage facilities for molybdate, which they bind with high specificity. High resolution structures of MopII in a number of states, including the first structure of an apo-molbindin, together with calorimetric data, allow us to describe ligand binding and provide support for the proposed storage function of the protein.