BPCPPDYSOE21 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 11: Poster A: Single Molecule, Multicellular, Bioimaging, Focus Sessions, etc.

BP 11.5: Poster

Montag, 22. März 2021, 16:30–19:00, BPp

Acidic amino acids do not affect the robustness of protein hydration layers to changes in KCl concentration — •Hosein Geraili¹ and Ana Vila Verde² — ¹MPI of Colloids and Interfaces, Dept Theory and Bio-Systems, Potsdam, Germany — ²U. Duisburg-Essen, Physics, Duisburg, Germany

The proteins of halophilic microorganisms have a higher content in negatively charged amino acids compared to microorganisms living in normal environments. One proposed hypothesis explaining this large content in acidic residues is that they are necessary to maintain the proteins at normal hydration levels in an environment with high salt concentration, i.e., in low water activity. To investigate protein hydration in high salt concentration using Molecular Dynamics, we optimized the interaction potential between potassium ions and the carboxylate side-chain of acidic amino acids; the optimized potential is compatible with the widely-used suite of AMBER force fields and the TIP3P water model. We compared hydration levels of 5 halophilic proteins and 5 non-halophilic ones. Our simulations show that all proteins have almost identical levels of hydration in high and low KCl concentrations: the large fraction of acidic amino acids in halophilic proteins is not necessary to ensure that they remain hydrated. We quantified the translational dynamics of the solvation shell of the halophilic and non-halophilic proteins, and observe almost no difference between them. The claim that acidic residues cooperatively interacting with the solvated network of ions would markedly decrease the dynamics of the protein solvation shell is not supported by our calculations.