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Nucleic Acids Res. 2015 Oct 15;43(18):e119. doi: 10.1093/nar/gkv577. Epub 2015 Jun 26.

Varying levels of complexity in transcription factor binding motifs.

Author information

1
Institute for Biosafety in Plant Biotechnology, Julius Kühn-Institut (JKI) - Federal Research Centre for Cultivated Plants, D-06484 Quedlinburg, Germany jens.keilwagen@jki.bund.de.
2
Institute of Computer Science, Martin Luther University Halle-Wittenberg, D-06099 Halle (Saale), Germany.

Abstract

Binding of transcription factors to DNA is one of the keystones of gene regulation. The existence of statistical dependencies between binding site positions is widely accepted, while their relevance for computational predictions has been debated. Building probabilistic models of binding sites that may capture dependencies is still challenging, since the most successful motif discovery approaches require numerical optimization techniques, which are not suited for selecting dependency structures. To overcome this issue, we propose sparse local inhomogeneous mixture (Slim) models that combine putative dependency structures in a weighted manner allowing for numerical optimization of dependency structure and model parameters simultaneously. We find that Slim models yield a substantially better prediction performance than previous models on genomic context protein binding microarray data sets and on ChIP-seq data sets. To elucidate the reasons for the improved performance, we develop dependency logos, which allow for visual inspection of dependency structures within binding sites. We find that the dependency structures discovered by Slim models are highly diverse and highly transcription factor-specific, which emphasizes the need for flexible dependency models. The observed dependency structures range from broad heterogeneities to sparse dependencies between neighboring and non-neighboring binding site positions.

PMID:
26116565
PMCID:
PMC4605289
DOI:
10.1093/nar/gkv577
[Indexed for MEDLINE]
Free PMC Article

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