<i>ATSAS 3.0</i>: expanded functionality and new tools for small-angle scattering data analysis

Abstract

The <i>ATSAS</i> software suite encompasses a number of programs for the processing, visualization, analysis and modelling of small-angle scattering data, with a focus on the data measured from biological macromolecules. Here, new developments in the <i>ATSAS 3.0</i> package are described. They include <i>IMSIM</i>, for simulating isotropic 2D scattering patterns; <i>IMOP</i>, to perform operations on 2D images and masks; <i>DATRESAMPLE</i>, a method for variance estimation of structural invariants through parametric resampling; <i>DATFT</i>, which computes the pair distance distribution function by a direct Fourier transform of the scattering data; <i>PDDFFIT</i>, to compute the scattering data from a pair distance distribution function, allowing comparison with the experimental data; a new module in <i>DATMW</i> for Bayesian consensus-based concentration-independent molecular weight estimation; <i>DATMIF</i>, an <i>ab initio</i> shape analysis method that optimizes the search model directly against the scattering data; <i>DAMEMB</i>, an application to set up the initial search volume for multiphase modelling of membrane proteins; <i>ELLLIP</i>, to perform quasi-atomistic modelling of liposomes with elliptical shapes; <i>NMATOR</i>, which models conformational changes in nucleic acid structures through normal mode analysis in torsion angle space; <i>DAMMIX</i>, which reconstructs the shape of an unknown intermediate in an evolving system; and <i>LIPMIX</i> and <i>BILMIX</i>, for modelling multilamellar and asymmetric lipid vesicles, respectively. In addition, technical updates were deployed to facilitate maintainability of the package, which include porting the <i>PRIMUS</i> graphical interface to Qt5, updating <i>SASpy</i> - a <i>PyMOL</i> plugin to run a subset of <i>ATSAS</i> tools - to be both Python 2 and 3 compatible, and adding utilities to facilitate mmCIF compatibility in future <i>ATSAS</i> releases. All these features are implemented in <i>ATSAS 3.0</i>, freely available for academic users at https://www.embl-hamburg.de/biosaxs/software.html.