title: Role of histidine for charge regulation of unstructured peptides at interfaces and in bulk.
abstract: Histidine-rich, unstructured peptides adsorb to charged interfaces such as mineral surfaces and microbial cell membranes. At a molecular level, we investigate the adsorption mechanism as a function of pH, salt, and multivalent ions showing that (1) proton charge fluctuations are-in contrast to the majority of proteins-optimal at neutral pH, promoting electrostatic interactions with anionic surfaces through charge regulation and (2) specific zinc(II)-histidine binding competes with protons and ensures an unusually constant charge distribution over a broad pH interval. In turn, this further enhances surface adsorption. Our analysis is based on atomistic molecular dynamics simulations, coarse grained Metropolis Monte Carlo, and classical polymer density functional theory. This multiscale modeling provides a consistent picture in good agreement with experimental data on Histatin 5, an antimicrobial salivary peptide. Biological function is discussed and we suggest that charge regulation is a significant driving force for the remarkably robust activity of histidine-rich antimicrobial peptides.
authors.affiliation: Division of Theoretical Chemistry, Lund University, P.O. Box 124, SE-22100, Lund, Sweden.
authors.forename: Anıl
authors.initials: A
authors.lastname: Kurut
authors.forename: João
authors.initials: J
authors.lastname: Henriques
authors.forename: Jan
authors.initials: J
authors.lastname: Forsman
authors.forename: Marie
authors.initials: M
authors.lastname: Skepö
authors.forename: Mikael
authors.initials: M
authors.lastname: Lund
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry; D054808:Histatins / Q000737:chemistry* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D064267:Intrinsically Disordered Proteins / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D009010:Monte Carlo Method; D017510:Protein Folding; D011506:Proteins / Q000737:chemistry*; D011522:Protons; D055672:Static Electricity; D000099053:Histidine-Rich Glycoprotein
chemical_list: D000890:Anti-Infective Agents; C068075:HTN3 protein, human; D054808:Histatins; D064267:Intrinsically Disordered Proteins; D011506:Proteins; D011522:Protons; D000099053:Histidine-Rich Glycoprotein
keywords: Monte Carlo simulations; adsorption of unstructured proteins; antimicrobial activity; charge regulation; histidine richness; specific metal binding