ABSTRACT
The hybrid plasmid-replication initiator protein RepDC, which is a fusion of the catalytic fragment of the RepD protein and the DNA-binding fragment of the RepC protein from Staphylococcus aureus, has been successfully crystallized and X-ray data to 3.5 A have been collected on a synchrotron radiation source. Crystals belong to space group I4132 with unit-cell dimensions a = b = c = 165.1 A. The crystals are estimated to contain one protein monomer per asymmetric unit, with 55% solvent content.
Subject(s)
Bacterial Proteins/chemistry , DNA-Binding Proteins , Bacterial Proteins/genetics , Crystallization , Crystallography, X-Ray , DNA Helicases/chemistry , DNA Helicases/genetics , DNA, Circular/chemistry , DNA, Circular/genetics , Plasmids/chemistry , Protein Conformation , Staphylococcus aureus/chemistry , Trans-Activators/chemistry , Trans-Activators/geneticsABSTRACT
DNA location in the crystal of the nonspecific lambda cro/(GT)4.(AC)4 complex has been studied by the isomorphous replacement method using iodinated and brominated oligonucleotides. The results of the search for heavy atom positions combined with previously obtained molecular replacement data suggest that the DNA octamer occupies two overlapping positions, each of the two duplexes (GTGTGTGT).(ACACACAC) belonging to the same imaginary longer double helix and differing only in the shift by two base pairs along the common sugar-phosphate backbone. In the crystals of the heavy atom derivatives different orientations of the DNA octamer are observed as well. It seems reasonable that the DNA mobility of both kinds might be a common feature of crystals of nonspecific repressor/DNA complexes.
