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Profile-based alignment algorithms for protein three-dimensional structure prediction

Prof. Aleksandar Poleksic
University of Northern Iowa

Friday, April 10, 2009
4:00-5:00pm, 140 SH

Abstract

The three-dimensional structure of a protein is key to understanding its function. However, the protein structure determination by X-ray crystallography or NMR spectroscopy is time- and resource-consuming process. Various computational methods have been proposed to address the drawbacks of the experimental techniques. These methods predict (rather than accurately determine) the structure of a protein from its primary sequence. For example, the structure of a protein can be approximated based upon the relationship (alignment) between the protein's primary sequence and the amino acid sequence of another protein of known structure (template). This approach, known as comparative modeling (or homology modeling), is currently the most accurate protein structure prediction method, but its usefulness is limited by the quality of the alignment between the query and the template protein. A number of computational techniques have been developed to overcome this limitation, including profile-based algorithms for sequence alignment.

We study the relationship between the accuracy of a profile-profile alignment algorithm and the size of the sequence profiles, where the profile size is defined as the average number of different residue types observed at profile's positions. Using an in-house alignment method UNI-FOLD, we demonstrate that optimizing the size of sequence profiles can dramatically improve the inference of weak relationships between protein sequences. Our method performs particularly well at the SCOP superfamily level, recognizing over 69% of superfamily relationships in the Lindahl benchmark for fold recognition.

Short Biography: Aleksandar Poleksic, Ph.D., is an Assistant Professor in the Department of Computer Science at the University of Northern Iowa. His training and interests span the fields of computational biology and bioinformatics, with a strong emphasis on novel algorithm and application development. Prior to joining UNI, Dr. Poleksic was a Senior Scientist at Eidogen-Sertanty, Inc., where he helped develop Eidogen's computational drug discovery platform that integrates numerous algorithms in the area of protein structure determination and analysis. Dr. Poleksic was recently granted a United States patent for alignment algorithms and methodologies for rapid protein homology detection.

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