A sequence and structure based model to explain information content relation with growth temperature

APTEKMANN A; SÁNCHEZ IE; NADRA AD

Bahía Blanca

Congreso; Sexto congreso de la Asociación Argentina de Bioinformática y Biología Computacional; 2015

A2B2C

We previously studied the relation between optimal growth temperature (OGT) and information content (IC), in the core promoter region of all the archeal genomes published to date, by calculating the information content of the motiff that represents the TATA binding site (TBS). We tested different approaches to predict transcription start sites (TSS) in a given genome we then used motiff prediction software in the flanking regions to the TSS, we constructed a database, compiling already available information from published sources, that contains characteristic growth conditions for each strain. Our work hipotesis is that protein-dna interfase in thermophiles should be different from that of mesophiles.We propose and test a positive correlation between information content (IC) of binding sites and OGT in archeas. We show that the IC increases with increasing optimal growth temperature, and this effect cannot be explained solely by an increased CG composition Figure 2. Selective pressure towards binding sites with higher binding affinity to the protein could be the reason for this correlation, if higher binding energys where selected we would expect an increase in high IC sites and a decrease in low IC sites as described in Figure 1 . The diversity of binding sites for a especific binder can be described by information theory tools. In this work we use the relation between information content and binding energy to explain the observed results. We built a sequence based model, based upon the concept of the information content of single sequences developed by schneider and combined a structural analysis to test this posibility. The established Rseq = Rfreq from molecular information theory does not take into account the effect of temperature as a selective pressure acting to skew the posible binding sites, and creating a cause for an increment in Rseq that does not apply to Rfreq. Since entropy effects increase with temperature, Shannon entropy effects might as well. We hope this approach will help us understand the mechanism involved in binding site evolution under extreme conditions as well as show us a new facet of binding site characterization related to the frequency distribution of the information content, and eventually how to interpret asymmetries from an structural or thermodynamical point of view.