Search

The human NQO1 (hNQO1) is a flavin adenine nucleotide (FAD)‐dependent oxidoreductase that catalyzes the two‐electron reduction of quinones to hydroquinones, being essential for the antioxidant defense system, stabilization of tumor suppressors, and activation of quinone‐based chemotherapeutics. Moreover, it is overexpressed in several tumors, which makes it an attractive cancer drug target. To decipher new structural insights into the flavin reductive half‐reaction of the catalytic mechanism of hNQO1, we have carried serial crystallography experiments at new ID29 beamline of the ESRF to determine, to the best of our knowledge, the first structure of the hNQO1 in complex with NADH. We have also performed molecular dynamics simulations of free hNQO1 and in complex with NADH. This is the first structural evidence that the hNQO1 functional cooperativity is driven by structural communication between the active sites through long‐range propagation of cooperative effects across the hNQO1 structure. Both structural results and MD simulations have supported that the binding of NADH significantly decreases protein dynamics and stabilizes hNQO1 especially at the dimer core and interface. Altogether, these results pave the way for future time‐resolved studies, both at x‐ray free‐electron lasers and synchrotrons, of the dynamics of hNQO1 upon binding to NADH as well as during the FAD cofactor reductive half‐reaction. This knowledge will allow us to reveal unprecedented structural information of the relevance of the dynamics during the catalytic function of hNQO1. [ABSTRACT FROM AUTHOR]

ID23‐2 is a fixed‐energy (14.2 keV) microfocus beamline at the European Synchrotron Radiation Facility (ESRF) dedicated to macromolecular crystallography. The optics and sample environment have recently been redesigned and rebuilt to take full advantage of the upgrade of the ESRF to the fourth generation Extremely Brilliant Source (ESRF‐EBS). The upgraded beamline now makes use of two sets of compound refractive lenses and multilayer mirrors to obtain a highly intense (>1013 photons s−1) focused microbeam (minimum size 1.5 µm × 3 µm full width at half‐maximum). The sample environment now includes a FLEX‐HCD sample changer/storage system, as well as a state‐of‐the‐art MD3Up high‐precision multi‐axis diffractometer. Automatic data reduction and analysis are also provided for more advanced protocols such as synchrotron serial crystallographic experiments. [ABSTRACT FROM AUTHOR]

Sphingolipid metabolism is tightly controlled by enzymes to regulate essential processes in human physiology. The central metabolite is ceramide, a pro‐apoptotic lipid catabolized by ceramidase enzymes to produce pro‐proliferative sphingosine‐1‐phosphate. Alkaline ceramidases are transmembrane enzymes that recently attracted attention for drug development in fatty liver diseases. However, due to their hydrophobic nature, no specific small molecule inhibitors have been reported. We present the discovery and mechanism of action of the first drug‐like inhibitors of alkaline ceramidase 3 (ACER3). In particular, we chemically engineered novel fluorescent ceramide substrates enabling screening of large compound libraries and characterized enzyme:inhibitor interactions using mass spectrometry and MD simulations. In addition to revealing a new paradigm for inhibition of lipid metabolising enzymes with non‐lipidic small molecules, our data lay the ground for targeting ACER3 in drug discovery efforts. [ABSTRACT FROM AUTHOR]

Sample handling and manipulation for cryoprotection currently remain critical factors in X‐ray structural determination. While several microchips for macromolecular crystallization have been proposed during the last two decades to partially overcome crystal‐manipulation issues, increased background noise originating from the scattering of chip‐fabrication materials has so far limited the attainable resolution of diffraction data. Here, the conception and use of low‐cost, X‐ray‐transparent microchips for in situ crystallization and direct data collection, and structure determination at atomic resolution close to 1.0 Å, is presented. The chips are fabricated by a combination of either OSTEMER and Kapton or OSTEMER and Mylar materials for the implementation of counter‐diffusion crystallization experiments. Both materials produce a sufficiently low scattering background to permit atomic resolution diffraction data collection at room temperature and the generation of 3D structural models of the tested model proteins lysozyme, thaumatin and glucose isomerase. Although the high symmetry of the three model protein crystals produced almost complete data sets at high resolution, the potential of in‐line data merging and scaling of the multiple crystals grown along the microfluidic channels is also presented and discussed. [ABSTRACT FROM AUTHOR]

Native single‐wavelength anomalous dispersion (SAD) is the most attractive de novo phasing method in macromolecular crystallography, as it directly utilizes intrinsic anomalous scattering from native crystals. However, the success of such an experiment depends on accurate measurements of the reflection intensities and therefore on careful data‐collection protocols. Here, the low‐dose, multiple‐orientation data‐collection protocol for native SAD phasing developed at beamline X06DA (PXIII) at the Swiss Light Source is reviewed, and its usage over the last four years on conventional crystals (>50 µm) is reported. Being experimentally very simple and fast, this method has gained popularity and has delivered 45 de novo structures to date (13 of which have been published). Native SAD is currently the primary choice for experimental phasing among X06DA users. The method can address challenging cases: here, native SAD phasing performed on a streptavidin–biotin crystal with P21 symmetry and a low Bijvoet ratio of 0.6% is highlighted. The use of intrinsic anomalous signals as sequence markers for model building and the assignment of ions is also briefly described. A broadly applicable, simple and fast data‐collection strategy for native SAD is described, which has become the primary choice for experimental phasing among users of the macromolecular crystallography beamline X06DA (PXIII) at the Swiss Light Source. Its usage over the last four years is reviewed. [ABSTRACT FROM AUTHOR]

At the Swiss Light Source macromolecular crystallography (MX) beamlines the collection of serial synchrotron crystallography (SSX) diffraction data is facilitated by the recent DA+ data acquisition and analysis software developments. The SSX suite allows easy, efficient and high‐throughput measurements on a large number of crystals. The fast continuous diffraction‐based two‐dimensional grid scan method allows initial location of microcrystals. The CY+GUI utility enables efficient assessment of a grid scan's analysis output and subsequent collection of multiple wedges of data (so‐called minisets) from automatically selected positions in a serial and automated way. The automated data processing (adp) routines adapted to the SSX data collection mode provide near real time analysis for data in both CBF and HDF5 formats. The automatic data merging (adm) is the latest extension of the DA+ data analysis software routines. It utilizes the sxdm (SSX data merging) package, which provides automatic online scaling and merging of minisets and allows identification of a minisets subset resulting in the best quality of the final merged data. The results of both adp and adm are sent to the MX MongoDB database and displayed in the web‐based tracker, which provides the user with on‐the‐fly feedback about the experiment. Implementation of the complete synchrotron serial crystallography (SSX) suite for real‐time data collection and processing available at the Swiss Light Source macromolecular beamlines is reported. A detailed description of the latest software extensions, i.e. the SSX user interface, as well as online data processing and merging routines, is also given. [ABSTRACT FROM AUTHOR]