J. Appl. Cryst.の発刊に際して

Rapid improvements in sequencing and array-based platforms are resulting in a flood of diverse genome-wide data, including data from exome and whole-genome sequencing, epigenetic surveys, expression profiling of coding and noncoding RNAs, single nucleotide polymorphism (SNP) and copy number profiling, and functional assays. Analysis of these large, diverse data sets holds the promise of a more comprehensive understanding of the genome and its relation to human disease. Experienced and knowledgeable human review is an essential component of this process, complementing computational approaches. This calls for efficient and intuitive visualization tools able to scale to very large data sets and to flexibly integrate multiple data types, including clinical data. However, the sheer volume and scope of data pose a significant challenge to the development of such tools.

Integrative Genomics Viewer

Diffraction (X-ray, neutron and electron) and electron cryo-microscopy are powerful methods to determine three-dimensional macromolecular structures, which are required to understand biological processes and to develop new therapeutics against diseases. The overall structure-solution workflow is similar for these techniques, but nuances exist because the properties of the reduced experimental data are different. Software tools for structure determination should therefore be tailored for each method. Phenix is a comprehensive software package for macromolecular structure determination that handles data from any of these techniques. Tasks performed with Phenix include data-quality assessment, map improvement, model building, the validation/rebuilding/refinement cycle and deposition. Each tool caters to the type of experimental data. The design of Phenix emphasizes the automation of procedures, where possible, to minimize repetitive and time-consuming manual tasks, while default parameters are chosen to encourage best practice. A graphical user interface provides access to many command-line features of Phenix and streamlines the transition between programs, project tracking and re-running of previous tasks.

/pdf/macromolecular-structure-determination-using-x-rays-neutrons-7udc75ny0s.pdf

Macromolecular structure determination using X-rays, neutrons and electrons: recent developments in Phenix

Heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) respond to a variety of different external stimuli and activate G proteins. GPCRs share many structural features, including a bundle of seven transmembrane alpha helices connected by six loops of varying lengths. We determined the structure of rhodopsin from diffraction data extending to 2.8 angstroms resolution. The highly organized structure in the extracellular region, including a conserved disulfide bridge, forms a basis for the arrangement of the seven-helix transmembrane motif. The ground-state chromophore, 11-cis-retinal, holds the transmembrane region of the protein in the inactive conformation. Interactions of the chromophore with a cluster of key residues determine the wavelength of the maximum absorption. Changes in these interactions among rhodopsins facilitate color discrimination. Identification of a set of residues that mediate interactions between the transmembrane helices and the cytoplasmic surface, where G-protein activation occurs, also suggests a possible structural change upon photoactivation.

/pdf/crystal-structure-of-rhodopsin-a-g-protein-coupled-receptor-16y9vf8azt.pdf

Crystal Structure of Rhodopsin: A G Protein-Coupled Receptor

phenix.refine is a program within the PHENIX package that supports crystallographic structure refinement against experimental data with a wide range of upper resolution limits using a large repertoire of model parameterizations. It has several automation features and is also highly flexible. Several hundred parameters enable extensive customizations for complex use cases. Multiple user-defined refinement strategies can be applied to specific parts of the model in a single refinement run. An intuitive graphical user interface is available to guide novice users and to assist advanced users in managing refinement projects. X-ray or neutron diffraction data can be used separately or jointly in refinement. phenix.refine is tightly integrated into the PHENIX suite, where it serves as a critical component in automated model building, final structure refinement, structure validation and deposition to the wwPDB. This paper presents an overview of the major phenix.refine features, with extensive literature references for readers interested in more detailed discussions of the methods.

/pdf/towards-automated-crystallographic-structure-refinement-with-43hriikvv9.pdf

Towards automated crystallographic structure refinement with phenix.refine

Significance-testing of periodogram for short time series

Crystal structure of bee-venom phospholipase A2

New algorithms have been outlined for efficient calculation of the fast Fourier transform of data revealing crystallographic symmetries in previous papers by Rowicka, Kudlicki & Otwinowski [Acta Cryst. (2002), A58, 574-579; Acta Cryst. (2003), A59, 172-182; Acta Cryst. (2003), A59, 183-192]. The present paper deals with three implementation-related issues, which have not been discussed before. First, the shape of the FFT-asymmetric unit in the reciprocal space is discussed in detail. Next, a method is presented of reducing symmetry in-place, without the need to allocate memory for intermediate results. Finally, there is a discussion on how the algorithm can be used for the inverse Fourier transform. The results are derived for the case of the one-step symmetry reduction [Rowicka, Kudlicki & Otwinowski (2003). Acta Cryst. A59, 172-182]. The algorithms are also an important step in the more complicated cases of centered lattices [Rowicka, Kudlicki & Otwinowski (2003). Acta Cryst. A59, 183-192] and space groups with non-removable special positions, such as cubic groups [Rowicka, Kudlicki & Otwinowski (2004), in preparation]. In the present paper, as in our previous ones, complex-to-complex FFTs only are dealt with. Modifications needed to adapt the results to data with Hermitian symmetry will be described in our forthcoming article [Kudlicki, Rowicka & Otwinowski (2004), in preparation].

The crystallographic fast Fourier transform. IV. FFT-asymmetric units in the reciprocal space.

The beam-image shift method accelerates data acquisition in cryo-EM single particle reconstruction (cryo-EM SPR) by fast repositioning of the imaging area, but at the cost of more severe and complex optical aberrations. We analyze here how uncorrected anti-symmetric aberrations, such as coma and trefoil, affect cryo-EM SPR results, and then infer an analytical formula quantifying information loss due to their presence that explains why Fourier-shell coefficient (FSC)-based statistics may report significantly overestimated resolution if these aberrations are not fully corrected. We validate our analysis with reference-based aberration refinement for two cryo-EM SPR datasets acquired with a 200 kV microscope in the presence of coma exceeding 40 μm, and obtained 2.3 and 2.7 A reconstructions for 144 and 173 kDa particles, respectively. Our results provide a description of an efficient approach for assessing information loss in cryo-EM SPR data acquired in the presence of higher-order aberrations and address inconsistent guidelines regarding the level of aberrations acceptable in cryo-EM SPR experiments.

https://www.biorxiv.org/content/biorxiv/early/2019/10/08/798280.full.pdf

High-resolution cryo-EM reconstructions in the presence of substantial aberrations

Structural characterization of shikimate pathway multi-enzyme Aro1 from opportunistic fungal pathogen Candida albicans provides the first molecular image of all five domains. Only four of these domains are active and individually essential for C. albicans viability. In the human fungal pathogen Candida albicans, ARO1 encodes an essential multi-enzyme that catalyses consecutive steps in the shikimate pathway for biosynthesis of chorismate, a precursor to folate and the aromatic amino acids. We obtained the first molecular image of C. albicans Aro1 that reveals the architecture of all five enzymatic domains and their arrangement in the context of the full-length protein. Aro1 forms a flexible dimer allowing relative autonomy of enzymatic function of the individual domains. Our activity and in cellulo data suggest that only four of Aro1’s enzymatic domains are functional and essential for viability of C. albicans, whereas the 3-dehydroquinate dehydratase (DHQase) domain is inactive because of active site substitutions. We further demonstrate that in C. albicans, the type II DHQase Dqd1 can compensate for the inactive DHQase domain of Aro1, suggesting an unrecognized essential role for this enzyme in shikimate biosynthesis. In contrast, in Candida glabrata and Candida parapsilosis, which do not encode a Dqd1 homolog, Aro1 DHQase domains are enzymatically active, highlighting diversity across Candida species.

/pdf/molecular-analysis-and-essentiality-of-aro1-shikimate-3080obsf.pdf

Molecular analysis and essentiality of Aro1 shikimate biosynthesis multi-enzyme in Candida albicans

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