Mobile barrier mechanisms for Na⁺-coupled symport in an MFS sugar transporter.

ABSTRACT: While many 3D structures of cation-coupled transporters have been determined, the mechanistic details governing the obligatory coupling and functional regulations still remain elusive. The bacterial melibiose transporter (MelB) is a prototype of major facilitator superfamily transporters. With a conformation-selective nanobody, we determined a low-sugar affinity inward-facing Na⁺-bound cryoEM structure. The available outward-facing sugar-bound structures showed that the N- and C-terminal residues of the inner barrier contribute to the sugar selectivity. The inward-open conformation shows that the sugar selectivity pocket is also broken when the inner barrier is broken. Isothermal titration calorimetry measurements revealed that this inward-facing conformation trapped by this nan

SUBMITTER: Hariharan P 

PROVIDER: S-EPMC10942615 | biostudies-literature | 2024 Feb

REPOSITORIES: biostudies-literature