Dynamics of interaction between the molecular motor SpoIIIE and DNA

BORGES, AUGUSTO; CATTONI DIEGO; NÖLLMANN MARCELO; CHARA OSVALDO

Buenos Aires

Conferencia; Latin American Conference on Mathematical Modelling of Biological Systems; 2015

Sociedad Argentina de Biofisica (SAB)

SpoIIIE are membrane-anchored, ATP-fueled, molecular motorswhich transport DNA, segregating chromosomes in bacteria andconsequently being crucial for sporulation. Directionality in these motors is ruled by interactions of specialized sequence-recognition domains with highly skewed DNA sequences known as SRS. We previously proposed a molecular mechanism responsible for SpoIIIE directionality based on a passive target search mechanism by which the SpoIIIE protein encounters SRS sequences1. In this project we implemented this mechanism in a stochastic model in which SpoIIIE can interact with DNA, either through specific sequences SRS or non-specific ones. Once bound to DNA containing or not SRS sequences, SpoIIIE is able to undergo 1D diffusion on the DNA chain and eventually unbind, thus, becoming available to bind another or the same DNA molecule. Pre-equilibrium binding experimental data previously reported for SpoIIIE-DNA systems allowed us to estimatemodel affinity parameters. By using this model we were able to explore alternative hypotheses regarding SpoIIIE interaction with DNA. We concluded that the sequence recognition process performed by SpoIIIE is mainly ruled by anomalous 1D diffusion.[1] Cattoni et al., 2013. EMBO Rep. 14(5):473-9.We acknowledge support for this research to the Human Frontiers Science Program (HFSP).