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Iowa State University

Changhui Yan

Bioinformatics & Computational Biology Student Seminar Series

Protein function classification using both sequence and structural features

Changhui Yan
Major professor: Dr. Vasant Honavar
Iowa State University
Friday, March 15, 2002
1:10 p.m.
1420 Molecular Biology Building

Abstract
It has been established that protein function is largely determined by its structure, which in turn is determined by its sequence. Proteins with similar structure or function often share sequence motifs. Such conserved sequence motifs have been used to predict protein functions. Previous work in our group has shown that classifiers for assigning proteins to one of several functional families using a combination of motifs often outperform those that use a single characteristic motif for each family. Since protein function is largely determined by structure, it is possible to classify proteins according to their function.

In this talk, I will describe an approach of data-driven construction of protein function classifiers using sequence and/or structural features of proteins. I will compare the performance of classifiers that use sequence features alone, with those that use structural features alone, and with those that useboth sequence and structrural features. Preliminary results show that classifiers that use both sequence and structural features outperform those that use sequence or structural features alone.


Shiquan Wu

Bioinformatics & Computational Biology Student Seminar Series

Multiple genome rearrangement

Shiquan Wu
Major Professors: Dr. Xun Gu and Dr. Zhijun Wu
Iowa State University
Friday, March 15, 2002
1:10 p.m.
1420 Molecular Biology Building

Abstract
There are various kinds of phylogenetic trees. One is measured in term of the number of mutations for transforming one genome (order of genes) into another. A multiple genome rearrangement problem is discussed in this talk: Given two collections of genomes, represented by permutations of genes, and a set of mutations (e.g., insertion, deletion, point mutation, reversal, etc.) we reconstruct the phylogenetic tree from one collection of genomes to the other by all possible given mutations in minimum number of steps. The pairwise sequence alignment problem is a typical one of this kind and is well-solved. The general problem is NP-hard. Efficient heuristics play an important role in finding the optimal solutions. We consider the case that a collection of genomes is generated from one genome, e.g., the identity permutation, in a minimum number of pure signed reversals. We introduce a series of approximation algorithms for finding the optimal solutions of multiple genome rearrangement problems. We then show how the search algorithms are applied to phylogenetic tree reconstructions.


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