Crystal structure of exonuclease RecJ bound to manganese ion

Abstract

IP is one of the most powerful detectors for collecting diffraction data in the sense that it has a wide detection area, high sensitivity, large dynamic range, high accuracy, and reasonable pixel size. In spite of such excellent features, a high-speed automatic data collection device that has enough speed to maximize use of SR X-rays is very difficult to make, due to the slow digitization speed of the IP. We have solved this difficulty by using a fully cylindrical IP cassette (radius = 400 mm, width = 450 mm) where several diffraction images can be recorded and be read by five IP reading heads. This devise called Galaxy has been developed and installed at BL6C in the PF. Net digitization time is 5 min and 2.5 min for pixel size being 100ƒÊm and 200ƒÊm, respectively. This is enough speed for a PF bending magnet beamline. This means, that when 2.88 Å resolution data using 1.0 Å x-rays are collected, a digitized speed for a diffraction image is 16.6sec for 100ƒÊm pixel size, because in this condition, 18 images can be recorded in an IP cassette. Additionally, the maximum resolution is 0.58° for 1.0 Å x-rays.Two examples follow;(1) sample crystal is Insulin, collected up to 1.0 Å collection range ; ƒ¢ƒ=63°, completeness=0.83, average redundancy= 1.42 and R-merge is 4.79%, (2) Citidine; data up to 0.7Å were recorded only 4 sheets using Weissenberg mode, with 80° on each sheet, completeness = 0.58, redundancy = 4.49 and R-merge = 3.2%. Keywords: IMAGING PLATE, PROTEIN CRYSTALLOGRAPHY, AUTOMATIC DIFFRACTION INTENSITY DATA COLLECTION SYSTEMActa Cryst. (2002). A58 (Supplement), C237 CCD-based detectors have become a key tool for x-ray crystallography, both at synchrotron beam lines and in the home laboratory. However, the performance of CCD-based detectors is fundamentally limited by the characteristics of the phosphor screens used to convert the incident x-ray flux to visible light. In particular, the spatial resolution of the detector is limited by photon scattering in the polycrystalline phosphor matrix. Also, the active areas which can be achieved are limited by the quantum efficiency of the phosphor. Here we describe a fundamentally new technology for the detection of x-ray quanta: the Quantum Resonance Converter (QRC). QRC technology allows quantum efficiencies several times higher than conventional phosphor screens and also eliminates the PSF degradation due to scattering. We describe the operation of these novel devices and report on their first experimental tests. Sulfolobus solfataricus P2 DNA polymerase IV (Dpo4) is a member of the newly classified Y-family of DNA polymerases. The Y-family polymerases are best characterized by their low-fidelity synthesis on undamaged DNA templates and propensity to traverse normally replication-blocking lesions. Crystal structures of Dpo4 in ternary complexes with DNA and an incoming nucleotide, either correct or incorrect, have been solved at 1.7 Å and 2.1 Å resolution, respectively. Despite a conserved active site and a hand-like configuration similar to all known polymeras...