Fluc simulations propose different fluoride routes through its two pores
Molecular simulations suggest that the two pores of bacterial Fluc handle fluoride differently despite their similar protein building blocks. One favoured single-ion motion; the other also allowed ions to push one another forward. The peer-reviewed computational study proposes a moving sodium cofactor, but rare complete crossings and accelerated conditions limit conclusions about transport in living cells.
Science··Midday
Similar protein halves give different routes
The bacterial fluoride channel Fluc contains two pores built from matching protein units arranged in opposite directions. A peer-reviewed computational study proposes that this arrangement supports different transport mechanisms in the two pores. Fluoride tended to move singly through one route, with longer waiting times near its entrance. In the other, an approaching ion could help push a leading ion outward through electrostatic repulsion. The movements were simulated at molecular scale. No new live-cell experiment was performed.[1]
Sodium acts as a moving helper
A sodium ion near the centre of the channel moved within its binding site and interacted with passing fluoride. In the single-ion route it attracted fluoride strongly, which could delay release. In the other pore it helped position the leading fluoride before the next ion displaced it. This offers a possible functional role for sodium beyond holding the protein structure together. The proposed contribution to fluoride selectivity, including what other central ions might permit, still needs experimental testing.[1]
Rare crossings limit the model’s reach
Researchers used 72 simulation setups spanning different fluoride occupancies, concentrations and charge imbalances across a double-membrane system. Some imposed unusually large membrane potentials to make rare events easier to sample. Such accelerated conditions can distort structures, and complete crossings remained limited. Statistical models of movement also depend on how positions are divided into states. The simulations thus supply testable mechanisms for the two pores, while leaving their relative importance under normal cellular conditions unresolved.[1]
