Computational Investigation of the pH Dependence of Stability of Melanosome Proteins: Implication for Melanosome formation and Disease. Academic Article uri icon

Overview

abstract

  • Intravesicular pH plays a crucial role in melanosome maturation and function. Melanosomal pH changes during maturation from very acidic in the early stages to neutral in late stages. Neutral pH is critical for providing optimal conditions for the rate-limiting, pH-sensitive melanin-synthesizing enzyme tyrosinase (TYR). This dramatic change in pH is thought to result from the activity of several proteins that control melanosomal pH. Here, we computationally investigated the pH-dependent stability of several melanosomal membrane proteins and compared them to the pH dependence of the stability of TYR. We confirmed that the pH optimum of TYR is neutral, and we also found that proteins that are negative regulators of melanosomal pH are predicted to function optimally at neutral pH. In contrast, positive pH regulators were predicted to have an acidic pH optimum. We propose a competitive mechanism among positive and negative regulators that results in pH equilibrium. Our findings are consistent with previous work that demonstrated a correlation between the pH optima of stability and activity, and they are consistent with the expected activity of positive and negative regulators of melanosomal pH. Furthermore, our data suggest that disease-causing variants impact the pH dependence of melanosomal proteins; this is particularly prominent for the OCA2 protein. In conclusion, melanosomal pH appears to affect the activity of multiple melanosomal proteins.

publication date

  • July 31, 2021

Research

keywords

  • Antigens, Neoplasm
  • Copper-Transporting ATPases
  • Melanosomes
  • Membrane Transport Proteins
  • Molecular Dynamics Simulation
  • Monophenol Monooxygenase
  • Protons

Identity

PubMed Central ID

  • PMC8347052

Scopus Document Identifier

  • 85111434863

Digital Object Identifier (DOI)

  • 10.1021/acs.jcim.8b00697

PubMed ID

  • 34361043

Additional Document Info

volume

  • 22

issue

  • 15