Significance of positively charged amino acids for the function of the Acidovorax delafieldii porin Omp34

Abstract

The functional significance of charged amino acids of the anion-selective porin Omp34 from Acidovorax delafieldii was investigated by means of conductance measurements. Chemical modification of Lys and Arg as well as titration of charges by adjusting the pH value revealed that positively charged amino acid residues determine the major functional properties of the porin. Positive charges are involved in creating the protein surface potential, the selectivity filter inside the channels, and the voltage-sensing and/or gating mechanisms. © 1995.