Benutzer:Crambin/SWISS-MODEL

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SWISS-MODEL ist ein Webserver im Bereich der strukturellen Bioinformatik zur vergleichenden Modellierung von 3-dimensionalen Proteinstrukturen. [1][2] Die vergleichende Strukturmodellierung (eng. Homology or comparative modelling) ist momentan die genaueste Methode der Proteinstrukturvorhersage und wird regelmäßig in einem breiten Spektrum von Anwendungen eingesetzt. 

Homology (or comparative) modelling methods make use of experimental protein structures ("templates") to build models for evolutionary related proteins ("targets").

Today, SWISS-MODEL consists of three tightly integrated components: (1) The SWISS-MODEL pipeline - a suite of software tools and databases for automated protein structure modelling,[1] (2) The SWISS-MODEL Workspace - a web-based graphical user workbench,[2] (3) The SWISS-MODEL Repository - a continuously updated database of homology models for a set of model organism proteomes of high biomedical interest.[3]

The Pipeline

SWISS-MODEL pipeline comprises the four main steps that are involved in building a homology model of a given protein structure:

  1. Identification of structural template(s). First, BLAST is used to fetch homologous sequences and if no suitable templates are found, HHsearch is used for detection of remotely related sequences. The templates are stored in the SWISS-MODEL Template Library (SMTL), which is derived from PDB.
  2. Alignment of target sequence and template structure(s).
  3. Model building and energy minimization. SWISS-MODEL implements a rigid fragment assembly approach for modelling.
  4. Assessment of the model's quality using three independent methods (QMEAN, ANOLEA, GROMOS).

The Workspace

The SWISS-MODEL Workspace integrates programs and databases required for protein structure modelling in a web-based workspace. Depending on the complexity of the modelling task, different modes of usage can be applied, in which the user has different levels of control over individual modelling steps: automated mode, alignment mode, and project mode. A fully automated mode is used when a sufficiently high sequence identity between target and template (>50%) allows for no human intervention at all. In this case only the sequence or UniProt accession code of the protein is required as input. The alignment mode enables the user to input their own target-template alignments from which the modelling procedure starts (i.e. search for templates step is skipped and rarely only minor changes in the provided alignment are made). The project mode is used in more difficult cases, when manual corrections of target-template alignments are needed to improve the quality of the resulting model. In this mode the input is a project file that can be generated by the DeepView (Swiss Pdb Viewer) visualization and structural analysis tool,[4] to allow the user to examine and manipulate the target-template alignment in its structural context. In all three cases the output is a pdb file with atom coordinates of the model or a DeepView project file. The four main steps of homology modelling may be repeated iteratively until a satisfactory model is achieved.

The SWISS-MODEL Workspace is accessible via the ExPASy web server, or it can be used as part of the program DeepView (Swiss Pdb-Viewer). As of February 2012 it has been cited 11000 times in scientific literature,[5] making it one of the most widely used tools for protein structure modelling. The tool is free for academic use.

The Repository

The SWISS-MODEL Repository provides access to an up-to-date collection of annotated three-dimensional protein models for a set of model organisms of high general interest. SWISS-MODEL Repository is integrated with several external resources, such as UniProt,[6] InterPro,[7] STRING,[8] and Nature PSI SBKB.[9]

New developments of the SWISS-MODEL expert system feature (1) automated modelling of homo-oligomeric assemblies; (2) modelling of essential metal ions and biologically relevant ligands in protein structures; (3) local (per-residue) model reliability estimates based on the QMEAN local score function;[10] (4) mapping of UniProt features to models. (1) and (2) are available when using the automated mode of the SWISS-MODEL Workspace; (3) is always provided when calculating an homology model using the SWISS-MODEL Workspace, and (4) is available in the SWISS-MODEL Repository.

Accuracy and reliability of the method

In the past, the accuracy, stability and reliability of the SWISS-MODEL server pipeline was validated by the EVA-CM benchmark project. Currently, the SWISS-MODEL server pipeline is participating in the CAMEO3D[1] (Continuous Automated Model EvaluatiOn) project which continuously evaluates the accuracy and reliability of protein structure prediction services in a fully automated manner.

References

Vorlage:Reflist

External links

See also

Category:Bioinformatics Category:Molecular modelling software

  1. ↑ a b Schwede T, Kopp J, Guex N, Peitsch MC: SWISS-MODEL: an automated protein homology-modeling server. In: Nucleic Acids Research. 31, Nr. 13, 2003, S. 3381–3385. doi:10.1093/nar/gkg520. PMID 12824332. PMC 168927 (freier Volltext).
  2. ↑ a b Arnold K, Bordoli L, Kopp J, and Schwede T: The SWISS-MODEL Workspace: A web-based environment for protein structure homology modelling. In: Bioinformatics. 22, Nr. 2, 2009, S. 195–201. doi:10.1093/bioinformatics/bti770. PMID 16301204.
  3. ↑ Kiefer F, Arnold K, Kunzli M, Bordoli L, et al.: The SWISS-MODEL Repository and associated resources. In: Nucleic Acids Research. 37, 2009, S. D387-392. doi:10.1093/nar/gkn750. PMID 18931379. PMC 2686475 (freier Volltext).
  4. ↑ Guex N, Peitsch MC, and Schwede T: Automated comparative protein structure modeling with SWISS-MODEL and Swiss-PdbViewer: a historical perspective. In: Electrophoresis. 30, Nr. Suppl 1, 2009, S. S162-173. doi:10.1002/elps.200900140. PMID 19517507.
  5. ↑ Number of results returned from a search in Google Scholar. (Google Scholar)
  6. ↑ Wu CH, Apweiler R, Bairoch A, et al.: The Universal Protein Resource (UniProt): an expanding universe of protein information. In: Nucleic Acids Research. 34, 2006, S. D187-91. doi:10.1093/nar/gkj161. PMID 16381842. PMC 1347523 (freier Volltext).
  7. ↑ Wu CH, Apweiler R, Bairoch A, et al.: InterPro and InterProScan: tools for protein sequence classification and comparison. In: Methods Mol Biol. 396, 2007, S. 59–70. PMID 18025686.
  8. ↑ Szklarczyk D, Franceschini A, Kuhn M, et al.: The STRING database in 2011: functional interaction networks of proteins, globally integrated and scored.. In: Nucleic Acids Research. 39, 2011, S. D561-8. doi:10.1093/nar/gkq973. PMID 21045058. PMC 3013807 (freier Volltext).
  9. ↑ Gabanyi MJ, Adams PD, Arnold K, et al.: The Structural Biology Knowledgebase: a portal to protein structures, sequences, functions, and methods.. In: J Struct Funct Genomics. 12, Nr. 2, 2011, S. 45–54. doi:10.1007/s10969-011-9106-2. PMID 21472436. PMC 3123456 (freier Volltext).
  10. ↑ Benkert P, Kunzli M, Schwede T: QMEAN server for protein model quality estimation.. In: Nucleic Acids Research. 37, Nr. Web Server issue, 2009, S. W510-4. doi:10.1093/nar/gkp322. PMID 19429685. PMC 2703985 (freier Volltext).
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