Software

BIPAD: A web server for modeling bipartite sequence elements

Chengpeng Bi^1,2 and Peter K Rogan^1,2

¹  Laboratory of Human Molecular Genetics, Children's Mercy Hospital & Clinics, 2401 Gillham Road, Kansas City, MO 64108, USA

²  School of Computer Science and Engineering, University of Missouri-Kansas City, 5115 Oak St., MO 64110, USA

author email corresponding author email

BMC Bioinformatics 2006, 7:76doi:10.1186/1471-2105-7-76

Published:	17 February 2006

Abstract

Background

Many dimeric protein complexes bind cooperatively to families of bipartite nucleic acid sequence elements, which consist of pairs of conserved half-site sequences separated by intervening distances that vary among individual sites.

Results

We introduce the Bipad Server [1], a web interface to predict sequence elements embedded within unaligned sequences. Either a bipartite model, consisting of a pair of one-block position weight matrices (PWM's) with a gap distribution, or a single PWM matrix for contiguous single block motifs may be produced. The Bipad program performs multiple local alignment by entropy minimization and cyclic refinement using a stochastic greedy search strategy. The best models are refined by maximizing incremental information contents among a set of potential models with varying half site and gap lengths.

Conclusion

The web service generates information positional weight matrices, identifies binding site motifs, graphically represents the set of discovered elements as a sequence logo, and depicts the gap distribution as a histogram. Server performance was evaluated by generating a collection of bipartite models for distinct DNA binding proteins.