Predicting functional sites with an automated algorithm suitable for heterogeneous datasets.
BACKGROUND
In a previous report (La et al., Proteins, 2005), we have demonstrated that the identification of phylogenetic motifs, protein sequence fragments conserving the overall familial phylogeny, represent a promising approach for sequence/function annotation. Across a structurally and functionally heterogeneous dataset, phylogenetic motifs have been demonstrated to correspond to a wide variety of functional site archetypes, including those defined by surface loops, active site clefts, and less exposed regions. However, in our original demonstration of the technique, phylogenetic motif identification is dependent upon a manually determined similarity threshold, prohibiting large-scale application of the technique.


RESULTS
In this report, we present an algorithmic approach that determines thresholds without human subjectivity. The approach relies on significant raw data preprocessing to improve signal detection. Subsequently, Partition Around Medoids Clustering (PAMC) of the similarity scores assesses sequence fragments where functional annotation remains in question. The accuracy of the approach is confirmed through comparisons to our previous (manual) results and structural analyses. Triosephosphate isomerase and arginyl-tRNA synthetase are discussed as exemplar cases. A quantitative functional site prediction assessment algorithm indicates that the phylogenetic motif predictions, which require sequence information only, are nearly as good as those from evolutionary trace methods that do incorporate structure.


CONCLUSIONS
The automated threshold detection algorithm has been incorporated into MINER, our web-based phylogenetic motif identification server. MINER is freely available on the web at http://www.pmap.csupomona.edu/MINER/. Pre-calculated functional site predictions of the COG database and an implementation of the threshold detection algorithm, in the R statistical language, can also be accessed at the website.
La
David
D
Department of Biological Sciences, California State Polytechnic University, Pomona, California 91768, USA. dla@csupomona.edu
Livesay
Dennis R
DR
D000465:Algorithms; D020816:Amino Acid Motifs; D001331:Automation; D001665:Binding Sites; D016000:Cluster Analysis; D019295:Computational Biology / Q000379:methods*; D003196:Computer Graphics; D003198:Computer Simulation; D017124:Conserved Sequence; D030562:Databases, Protein; D020407:Internet; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D012343:RNA, Transfer / Q000737:chemistry; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D012984:Software; D012985:Software Design; D014305:Triose-Phosphate Isomerase / Q000737:chemistry; D014584:User-Computer Interface
D012343:RNA, Transfer; D014305:Triose-Phosphate Isomerase