title: Domain organization of DNase from Thioalkalivibrio sp. provides insights into retention of activity in high salt environments.
abstract: Our study indicates that DNA binding domains are common in many halophilic or halotolerant bacterial DNases and they are potential activators of enzymatic activity at high ionic strength. Usually, proteins adapt to high ionic strength by increasing the number of negatively charged residues on the surface. However, in DNases such adaptation would hinder the binding to negatively charged DNA, a step critical for catalysis. In our study we demonstrate how evolution has solved this dilemma by engaging the DNA binding domain. We propose a mechanism, which enables the enzyme activity at salt concentrations as high as 4 M of sodium chloride, based on collected experimental data and domain structure analysis of a secreted bacterial DNase from the extremely halotolerant bacterium Thioalkalivibrio sp. K90mix. The enzyme harbors two domains: an N-terminal domain, that exhibits DNase activity, and a C-terminal domain, comprising a duplicate DNA binding helix-hairpin-helix motif. Here we present experimental data demonstrating that the C-terminal domain is responsible for the enzyme's resistance to high ionic strength.
authors.affiliation: Department of Eukaryote Gene Engineering, VU Institute of Biotechnology, Vilnius University Vilnius, Lithuania ; Thermo Fisher Scientific Vilnius, Lithuania.
authors.forename: Gediminas
authors.initials: G
authors.lastname: Alzbutas
authors.affiliation: Thermo Fisher Scientific Vilnius, Lithuania.
authors.forename: Milda
authors.initials: M
authors.lastname: Kaniusaite
authors.affiliation: Thermo Fisher Scientific Vilnius, Lithuania ; Faculty of Chemistry, Vilnius University Vilnius, Lithuania.
authors.forename: Algirdas
authors.initials: A
authors.lastname: Grybauskas
authors.affiliation: Thermo Fisher Scientific Vilnius, Lithuania.
authors.forename: Arunas
authors.initials: A
authors.lastname: Lagunavicius
keywords: DNA binding domain; DNase; HhH motif; Thioalkalivibrio sp.; adaptation; halophile