Impact of F80M and F83M mutations on the functionality of fluoride ion channel elucidated in microsecond level molecular dynamic simulation

Fluoride ion channels of the Fluc family plays a critically important role in combating environmental fluoride toxicity. As per the crystal structure of these fluoride ion channels, the pore region is densely packed with a series of hydrogen bond donating residues arranged in a ladder fashion creating an ion conducting pathway. In earlier studies, it was revealed that although the ion conducting pathway polarity is highly conserved, however the functionality of the channel protein depends on several residues at particular positions. While, a threonine at end of the pore is critically important in forming initial interactions, two phenylalanines at the central region coordinate F- transportation through the channel. It was also revealed that these two phenylalanines cannot be substituted by any other aromatic, polar or non-polar residues without hindering the functionality with exception of methionine. In another study, it was revealed that these two phenylalanines F80 and F83 when mutated with methionine; F80M lead to active state, while the F83M has lead to inactivity of F- anion conductivity. However, the exact atomic level detailing on how exactly these mutations have impacted the conductivity remained elusive. In this scenario, in this present study, we have modeled these two mutations and performed a microsecond level simulation on each mutation compared with wild type towards understanding the atomic level detailing revealing several insights on what exactly happening at these residues responsible for the selective conductivity of F- ions.

Automated summary

Fluoride ion channels of the Fluc family are crucial in combating environmental fluoride toxicity, with the functionality of the channel protein depending on specific residues at particular positions; the phenylalanines play a key role in F- transportation through the channel, and mutations at F80 and F83 to methionine have different impacts on channel activity.