Investigation of conformational sampling of LeuT due to Na site mutations at thr 354 and ser 355 with DEER EPR spectroscopy

LeuT, an integral membrane protein and member of the NSS family, is a bacterial homolog of human neurotransmitter transporters. The mechanism of LeuT transport has been described by three conformations captured by X-ray crystallography: outward-facing, outward-facing occluded, and inward-facing. To select for an inward-facing conformation, a number of conserved residues were mutated. Using DEER EPR spectroscopy, we have investigated the effects of one set of these mutations, T354V and S355A, in LeuT. In this data, we describe the effects of the loss of Na binding on the conformational sampling as well as evaluate whether the crystallographic inward-facing structures represents a natively-sampled LeuT conformation.