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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
50
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pubmed:dateCreated |
1999-1-14
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pubmed:abstractText |
In the accompanying paper, we demonstrated the presence of a fluorescence resonance energy transfer (FRET) between the tryptophans of the melibiose permease (MelB) of Escherichia coli and a fluorescent sugar, 2'-(N-5-dimethylaminonaphthalene-1-sulfonyl)aminoethyl-1-thio-beta-D- galactopyranoside (Dns2-S-Gal) bound at the sugar-binding site (Maehrel, C., Cordat, E., Mus-Veteau, I., and Leblanc, G. (1998) J. Biol. Chem. 273, 33192-33197). To identify the tryptophans that transfer their energy to the fluorescent sugar, we analyzed the FRET properties of MelB mutants carrying the replacement of each of the eight MelB tryptophans by a phenylalanine. The data indicate that Trp64, localized in loop 2-3 from the N-terminal domain, and Trp299, localized in helix IX in the C-terminal domain, are responsible for up to 80% of the FRET signal. Moreover, by assuming that only Trp299 transfers energy to Dns2-S-Gal in mutant W64F, whereas only Trp64 transfers energy to Dns2-S-Gal in mutant W299F, we calculated that Trp299 and Trp64 are about 14 and 20 A away from the probe, respectively. In addition, we observed that mutating Trp342, localized in helix X of the C-terminal domain, produces a significant increase of the polarity of the fluorescent sugar environment, suggesting its proximity to the sugar-binding site. Taken together, these data provide additional support for the suggestion that (i) the sugar-binding site is localized in the C-terminal part of the transporter, probably close to membrane segments IX and X, and (ii) the N-terminal domain, and particularly cytoplasmic loop 2-3, is also close to the sugar-binding site.
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pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical | |
pubmed:status |
MEDLINE
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pubmed:month |
Dec
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pubmed:issn |
0021-9258
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:day |
11
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pubmed:volume |
273
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
33198-202
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pubmed:dateRevised |
2006-11-15
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pubmed:meshHeading |
pubmed-meshheading:9837888-Energy Transfer,
pubmed-meshheading:9837888-Escherichia coli,
pubmed-meshheading:9837888-Membrane Transport Proteins,
pubmed-meshheading:9837888-Protein Structure, Secondary,
pubmed-meshheading:9837888-Spectrometry, Fluorescence,
pubmed-meshheading:9837888-Symporters,
pubmed-meshheading:9837888-Tryptophan
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pubmed:year |
1998
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pubmed:articleTitle |
Structural studies of the melibiose permease of Escherichia coli by fluorescence resonance energy transfer. II. Identification of the tryptophan residues acting as energy donors.
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pubmed:affiliation |
Laboratoire J. Maetz, Département de Biologie Cellulaire et Moléculaire du Commissariat à l'Energie Atomique and CNRS-ERS 1253, 06238 Villefranche sur Mer cedex, France.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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