Structural basis for Na+ transport mechanism by a light-driven Na+ pump

Krokinobacter eikastus rhodopsin 2 (KR2) is the first light-driven Na+ pump discovered, and is viewed as a potential next-generation optogenetics tool. Since the positively charged Schiff base proton, located within the ion-conducting pathway of all light-driven ion pumps, was thought to prohibit the transport of a non-proton cation, the discovery of KR2 raised the question of how it achieves Na+ transport. Here we present crystal structures of...