scholarly journals SAXSDom: Modeling multidomain protein structures using small‐angle X‐ray scattering data

2019 ◽  
Vol 88 (6) ◽  
pp. 775-787 ◽  
Author(s):  
Jie Hou ◽  
Badri Adhikari ◽  
John J. Tanner ◽  
Jianlin Cheng
2005 ◽  
Vol 127 (47) ◽  
pp. 16621-16628 ◽  
Author(s):  
Alexander Grishaev ◽  
Justin Wu ◽  
Jill Trewhella ◽  
Ad Bax

2020 ◽  
Vol 16 (3) ◽  
pp. 1985-2001 ◽  
Author(s):  
Christopher Prior ◽  
Owen R. Davies ◽  
Daniel Bruce ◽  
Ehmke Pohl

2019 ◽  
Author(s):  
Jie Hou ◽  
Badri Adhikari ◽  
John J. Tanner ◽  
Jianlin Cheng

AbstractMany proteins are composed of several domains that pack together into a complex tertiary structure. Some multidomain proteins can be challenging for protein structure modeling, particularly those for which templates can be found for the domains but not for the entire sequence. In such cases, homology modeling can generate high quality models of the domains but not for the assembled protein. Small-angle X-ray scattering (SAXS) reports on the solution structural properties of proteins and has the potential for guiding homology modeling of multidomain proteins. In this work, we describe a novel multi-domain protein assembly modeling method, SAXSDom, that integrates experimental knowledge from SAXS profiles with probabilistic Input-Output Hidden Markov model (IOHMM). Four scoring functions to account for the energetic contribution of SAXS restraints for domain assembly were developed and tested. The method was evaluated on multi-domain proteins from two public datasets. Based on the results, the accuracy of domain assembly was improved for 40 out of 46 CASP multi-domain proteins in terms of RMSD and TM-score when SAXS information was used. Our method also achieved higher accuracy for at least 45 out of 73 multi-domain proteins according to RMSD and TM-score metrics in the AIDA dataset. The results demonstrate that SAXS data can provide useful information to improve the accuracy of domain-domain assembly. The source code and tool packages are available at http://github.com/multicom-toolbox/SAXSDom.


2019 ◽  
Author(s):  
Christopher Prior ◽  
Owen R Davies ◽  
Daniel Bruce ◽  
Ehmke Pohl

ABSTRACTSmall angle X-ray scattering (SAXS) has become an important tool to investigate the structure of proteins in solution. In this paper we present a novel ab-initio method to represent polypeptide chains as discrete curves that can be used to derive a meaningful three-dimensional model from only the primary sequence and experimental SAXS data. High resolution crystal structures were used to generate probability density functions for each of the common secondary structural elements found in proteins. These are used to place realistic restraints on the model curve’s geometry. To evaluate the quality of potential models and demonstrate the efficacy of this novel technique we developed a new statistic to compare the entangled geometry of two open curves, based on mathematical techniques from knot theory. The chain model is coupled with a novel explicit hydration shell model in order derive physically meaningful 3D models by optimizing configurations against experimental SAXS data using a monte-caro based algorithm. We show that the combination of our ab-initio method with spatial restraints based on contact predictions successfully derives a biologically plausible model of the coiled–coil component of the human synaptonemal complex central element protein.SIGNIFICANCESmall-angle X-ray scattering allows for structure determination of biological macromolecules and their complexes in aqueous solution. Using a discrete curve representation of the polypeptide chain and combining it with empirically determined constraints and a realistic solvent model we are now able to derive realistic ab-initio 3-dimensional models from BioSAXS data. The method only require a primary sequence and the scattering data form the user.


2004 ◽  
Vol 37 (1) ◽  
pp. 103-109 ◽  
Author(s):  
Masaki Kojima ◽  
Alexander A. Timchenko ◽  
Junichi Higo ◽  
Kazuki Ito ◽  
Hiroshi Kihara ◽  
...  

A new algorithm to refine protein structures in solution from small-angle X-ray scattering (SAXS) data was developed based on restrained molecular dynamics (MD). In the method, the sum of squared differences between calculated and observed SAXS intensities was used as a constraint energy function, and the calculation was started from given atomic coordinates, such as those of the crystal. In order to reduce the contribution of the hydration effect to the deviation from the experimental (objective) curve during the dynamics, and purely as an estimate of the efficiency of the algorithm, the calculation was first performed assuming the SAXS curve corresponding to the crystal structure as the objective curve. Next, the calculation was carried out with `real' experimental data, which yielded a structure that satisfied the experimental SAXS curve well. The SAXS data for ribonuclease T1, a single-chain globular protein, were used for the calculation, along with its crystal structure. The results showed that the present algorithm was very effective in the refinement and adjustment of the initial structure so that it could satisfy the objective SAXS data.


2018 ◽  
Vol 122 (45) ◽  
pp. 10320-10329 ◽  
Author(s):  
Amin Sadeghpour ◽  
Marjorie Ladd Parada ◽  
Josélio Vieira ◽  
Megan Povey ◽  
Michael Rappolt

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