Description
The Phyre and Phyre2 servers predict the three-dimensional structure of a protein sequence using the principles and techniques of homology modeling. Because the structure of a protein is more conserved in evolution than its amino acid sequence, a protein sequence of interest (the target) can be modeled with reasonable accuracy on a very distantly related sequence of known structure (the template), provided that the relationship between target and template can be discerned throughStandard usage
After pasting a protein amino acid sequence into the Phyre or Phyre2 submission form, a user will typically wait between 30 minutes and several hours (depending on factors such as sequence length, number of homologous sequences and frequency and length of insertions and deletions) for a prediction to complete. An email containing summary information and the predicted structure in PDB format are sent to the user together with a link to a web page of results. The Phyre2 results screen is divided into three main sections, described below.Secondary structure and disorder prediction
The user-submitted protein sequence is first scanned against a large sequence database using PSI-BLAST. The profile generated by PSI-BLAST is then processed by the neural network secondary structure prediction program PsiPred and the protein disorder predictor Disopred. The predicted presence of alpha-helices, beta-strands and disordered regions is shown graphically together with a color-coded confidence bar.Domain analysis
Many proteins contain multipleDetailed template information
The main results table in Phyre2 provides confidence estimates, images and links to the three-dimensional predicted models and information derived from either Structural Classification of Proteins database (SCOP) or the Protein Data Bank (PDB) depending on the source of the detected template. For each match a link takes the user to a detailed view of the alignment between the user sequence and the sequence of known three-dimensional structure.Alignment view
The detailed alignment view permits a user to examine individual aligned residues, matches between predicted and known secondary structure elements and the ability to toggle information regarding patterns of sequence conservation and secondary structure confidence. In addition Jmol is used to permit interactive 3D viewing of the protein model.Improvements in Phyre2
Phyre2 uses a fold library that is updated weekly as new structures are solved. It uses a more up-to-date interface and offers additional functionality over the Phyre server as described below.Additional functionality
Batch processing
The batch processing feature permits users to submit more than one sequence to Phyre2 by uploading a file of sequences in FASTA format. By default, users have a limit of 100 sequences in a batch. This limit can be raised by contacting the administrator. Batch jobs are processed in the background on free computing power as it becomes available. Thus, batch jobs will often take longer than individually submitted jobs, but this is necessary to allow a fair distribution of computing resources to all Phyre2 users.One to one threading
One to one threading allows you to upload both a sequence you wish modelled AND the template on which to model it. Users sometimes have a protein sequence that they wish to model on a specific template of their choice. This may be for example a newly solved structure that is not in the Phyre2 database or because of some additional biological information that indicates the chosen template would produce a more accurate model than the one(s) automatically chosen by Phyre2.Backphyre
Instead of predicting the 3D structure of a protein sequence, often users have a solved structure and they are interested in determining if there is a related structure in a genome of interest. In Phyre2 an uploaded protein structure can be converted into a hidden Markov model and then scanned against a set of genomes (more than 20 genomes as of March 2011). This functionality is called "BackPhyre" to indicate how Phyre2 is being used in reverse.Phyrealarm
Sometimes Phyre2 can't detect any confident matches to known structures. However, the fold library database increases by about 40-100 new structures each week. So even though there might be no decent templates this week, there may well be in the coming weeks. Phyrealarm allows users to submit a protein sequence to be automatically scanned against new entries added to the fold library every week. If a confident hit is detected, the user is automatically notified by email together with the results of the Phyre2 search. Users can also control the level of alignment coverage and confidence in the match required to trigger an email alert.3DLigandSite
Phyre2 is coupled to the 3DLigandSite server for protein binding site prediction. 3DLigandSite has been one of the top performing servers for binding site prediction at the Critical Assessment of Techniques for Protein Structure Prediction (CASP) in ( CASP8 and CASP9). Confident models produced by Phyre2 (confidence >90%) are automatically submitted to 3DLigandSite.Transmembrane topology prediction
The program memsat_svm is used to predict the presence and topology of any transmembrane helices present in the user protein sequence.Multi-template modelling
Phyre2 permits users to choose 'Intensive' modelling from the main submission screen. This mode: * Examines the list of hits and applies heuristics in order to select templates that maximise sequence coverage and confidence. * Constructs models for each selected template. * Uses these models to provide pairwise distance constraints that are input to the ''ab initio'' and multi-template modelling tool Poing. * Poing synthesises the user protein in the context of these distance constraints, modelled by springs. Regions for which there is no template information are modelled by the ''ab initio'' simplified physics model of Poing. * The complete model generated by Poing is combined with the original templates as input to MODELLER.Applications
Applications of Phyre and Phyre2 include protein structure prediction, function prediction, domain prediction, domain boundary prediction, evolutionary classification of proteins, guiding site-directed mutagenesis and solving protein crystal structures by molecular replacement. There are two linked resources that use Phyre predictions for the structure-based analysis of missense variants typically resulting from single-nucleotide polymorphisms.History
Phyre and Phyre2 are the successors to the 3D-PSSM protein structure prediction system which has over 1400 citations to date. 3D-PSSM was designed and developed by Lawrence KelleyReferences
{{DEFAULTSORT:Phyre Phyre2 Bioinformatics software Computational science