Wolf B. Frommer
Publication Details
-
The SWEET glucoside transporter superfamily
Encyl. Biophysics. 2013: 2556-58
Soluble carbohydrates, principally derived from photosynthesis, serve as the preferred nutrient for many unicellular organisms, and as the dominant transported form for carbon and energy in multicellular organisms. Almost all cells from all kingdoms use carrier proteins to transport soluble carbohydrates across the lipid bilayers that enclose their cytoplasm. Today, at least three classes of carriers that mediate transport of sugars like glucose, maltose or sucrose are known, namely: (i) the sodium-dependent glucose transporters of the solute-sodium symporter family (SSS TCDB 2.A.21, and SLC2); (ii) the mono- and disaccharide transporters of the major facilitator superfamily (MFS TCDB 2.A.1 and SLC5), exemplified by the lactose transport protein, LacY; (iii) the sugar phosphotransferase superfamily (PTS TCDB 4.A.1-4); and (iv) the recently identified mono- and disaccharide transporters of the SWEET family (SLC50). The SWEET family has homologs in bacteria, in plants and in animals/humans (Chen et al., 2010). SWEETs are unique in that prokaryotic homologs are predicted to consist of only three transmembrane helices (Hu, Sosso, Frommer unpublished), while the eukaryotic transporters putatively contain seven transmembrane helices with a direct repeat of the bacterial three transmembrane helix motif connected by an additional central helix (Chen et al., 2010). Their small size makes them ideal candidates for structural analyses by NMR or crystallization. The Frommer group has demonstrated monosaccharide (glucose, mannose, fructose) transport activities for a number of plant and animal/human SWEETs as well as sucrose transport activities for several of the plant SWEETs (Chen et al., 2010; Chen et al., 2012).
Help