Title
SMURFLite: combining simplified Markov random fields with simulated evolution improves remote homology detection for beta-structural proteins into the twilight zone.
Abstract
Motivation: One of the most successful methods to date for recognizing protein sequences that are evolutionarily related has been profile hidden Markov models (HMMs). However, these models do not capture pairwise statistical preferences of residues that are hydrogen bonded in beta sheets. These dependencies have been partially captured in the HMM setting by simulated evolution in the training phase and can be fully captured by Markov random fields (MRFs). However, the MRFs can be computationally prohibitive when beta strands are interleaved in complex topologies. We introduce SMURFLite, a method that combines both simplified MRFs and simulated evolution to substantially improve remote homology detection for beta structures. Unlike previous MRF-based methods, SMURFLite is computationally feasible on any beta-structural motif. Results: We test SMURFLite on all propeller and barrel folds in the mainly-beta class of the SCOP hierarchy in stringent cross-validation experiments. We show a mean 26% (median 16%) improvement in area under curve (AUC) for beta-structural motif recognition as compared with HMMER (a well-known HMM method) and a mean 33% (median 19%) improvement as compared with RAPTOR (a well-known threading method) and even a mean 18% (median 10%) improvement in AUC over HHPred (a profile-profile HMM method), despite HHpred's use of extensive additional training data. We demonstrate SMURFLite's ability to scale to whole genomes by running a SMURFLite library of 207 beta-structural SCOP superfamilies against the entire genome of Thermotoga maritima, and make over a 100 new fold predictions.
Year
DOI
Venue
2012
10.1093/bioinformatics/bts110
BIOINFORMATICS
Keywords
Field
DocType
proteins,amino acid sequence,markov chains
Pairwise comparison,Random field,Computer science,Markov chain,Terminator (solar),Threading (manufacturing),Bioinformatics,Beta (finance),Hidden Markov model,Thermotoga maritima
Journal
Volume
Issue
ISSN
28
9
1367-4803
Citations 
PageRank 
References 
7
0.55
20
Authors
4
Name
Order
Citations
PageRank
Noah M. Daniels1373.87
Raghavendra Hosur2211.84
Bonnie Berger31643165.84
Lenore Cowen438838.37