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Major Facilitator Superfamily (major + facilitator_superfamily)

Distribution by Scientific Domains

Chemistry	80%

Selected Abstracts

The ABC transporter BcatrB from Botrytis cinerea is a determinant of the activity of the phenylpyrrole fungicide fludioxonil

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 5 2001
T Vermeulen
Abstract This study demonstrates that the ATP-binding cassette (ABC) transporter BcatrB from Botrytis cinerea influences the activity of phenylpyrrole fungicides against the pathogen. This conclusion is based on toxicity assays and northern analysis experiments which show that BcatrB replacement mutants, which do not express the BcatrB gene, show an increased sensitivity to the phenylpyrrole fungicides fludioxonil and fenpiclonil. Mutants overexpressing BcatrB exhibit a decreased sensitivity to these fungicides. In addition, accumulation of fludioxonil by BcatrB replacement mutants was higher than by wild-type isolates. For mutants overexpressing BcatrB the reverse was observed. Additional ABC and major facilitator superfamily (MFS) transporter genes were identified in an expressed sequence tag (EST) database, suggesting that B cinerea has gene families of ABC and MFS transporters. Corresponding fragments of ten ABC (BcatrC,BcatrN) and three MFS transporter genes (Bcmfs1,4) were cloned and characterised. Fludioxonil affected the transcript level of some members of these gene families in germlings during a short treatment with the fungicide at sub-lethal concentrations. Hence, other ABC and MFS transporters may affect the activity of phenylpyrrole fungicides as well. Other fungicides such as the anilinopyrimidine fungicide cyprodinil, the azole fungicide tebuconazole, the dicarboximide fungicide iprodione and the strobilurin fungicide trifloxystrobin also induced transcription of some of the ABC and MFS transporter genes identified. Therefore, we propose that various ABC and MFS transporters function in protection of the fungus against fungicides and are involved in multi-drug resistance development. © 2001 Society of Chemical Industry [source]

Sugarcane ShSUT1: analysis of sucrose transport activity and inhibition by sucralose

PLANT CELL & ENVIRONMENT, Issue 10 2006
ANKE REINDERS
ABSTRACT Plant sucrose transporters (SUTs) are members of the glycoside-pentoside-hexuronide (GPH) cation symporter family (TC2.A.2) that is part of the major facilitator superfamily (MFS). All plant SUTs characterized to date function as proton-coupled symporters and catalyze the cellular uptake of sucrose. SUTs are involved in loading sucrose into the phloem and sink tissues, such as seeds, roots and flowers. Because monocots are agriculturally important, SUTs from cereals have been the focus of recent research. Here we present a functional analysis of the SUT ShSUT1 from sugarcane, an important crop species grown for its ability to accumulate high amounts of sucrose in the stem. ShSUT1 was previously shown to be expressed in maturing stems and plays an important role in the accumulation of sucrose in this tissue. Using two-electrode voltage clamping in Xenopus oocytes expressing ShSUT1, we found that ShSUT1 is highly selective for sucrose, but has a relatively low affinity for sucrose (K0.5 = 8.26 mM at pH 5.6 and a membrane potential of ,137 mV). We also found that the sucrose analog sucralose (4,1,,6,-trichloro-4,1,,6,-trideoxy-galacto-sucrose) is a competitive inhibitor of ShSUT1 with an inhibition coefficient (Ki) of 16.5 mM. The presented data contribute to our understanding of sucrose transport in plants in general and in monocots in particular. [source]

Docking and homology modeling explain inhibition of the human vesicular glutamate transporters

PROTEIN SCIENCE, Issue 9 2007
Jonas Almqvist
Abstract As membrane transporter proteins, VGLUT1,3 mediate the uptake of glutamate into synaptic vesicles at presynaptic nerve terminals of excitatory neural cells. This function is crucial for exocytosis and the role of glutamate as the major excitatory neurotransmitter in the central nervous system. The three transporters, sharing 76% amino acid sequence identity in humans, are highly homologous but differ in regional expression in the brain. Although little is known regarding their three-dimensional structures, hydropathy analysis on these proteins predicts 12 transmembrane segments connected by loops, a topology similar to other members in the major facilitator superfamily, where VGLUT1,3 have been phylogenetically classified. In this work, we present a three-dimensional model for the human VGLUT1 protein based on its distant bacterial homolog in the same superfamily, the glycerol-3-phosphate transporter from Escherichia coli. This structural model, stable during molecular dynamics simulations in phospholipid bilayers solvated by water, reveals amino acid residues that face its pore and are likely to affect substrate translocation. Docking of VGLUT1 substrates to this pore localizes two different binding sites, to which inhibitors also bind with an overall trend in binding affinity that is in agreement with previously published experimental data. [source]

Structural conservation in the major facilitator superfamily as revealed by comparative modeling

PROTEIN SCIENCE, Issue 7 2004
Eyal Vardy
Abstract The structures of membrane transporters are still mostly unsolved. Only recently, the first two high-resolution structures of transporters of the major facilitator superfamily (MFS) were published. Despite the low sequence similarity of the two proteins involved, lactose permease and glycerol-3-phosphate transporter, the reported structures are highly similar. This leads to the hypothesis that all members of the MFS share a similar structure, regardless of their low sequence identity. To test this hypothesis, we generated models of two other members of the MFS, the Tn10-encoded metal-tetracycline/H+ antiporter (TetAB) and the rat vesicular monoamine transporter (rVMAT2). The models are based on the two MFS structures and on experimental data. The models for both proteins are in good agreement with the data available and support the notion of a shared fold for all MFS proteins. [source]