Naslov
Monitoring the unfolding pathway of the L-leucine binding proteins of E. coli by F-19 NMR and fluorescence spectroscopy

Autori
Luck, Linda A. ; Salopek-Sondi, Branka ; Swartz, Derrick J. ; Barcomb, T. F.

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Protein Science (ISSN 0961-8368), Vol. 12, Suppl. 1 / Hermodson, Mark - Lahti : Cold Spring Harbor Laboratory (CSHL), 2003, 173-173

Skup
Fifth European Symposium of the Protein Society

Mjesto i datum
Firenca, Italija, 29.03.2003. - 02.04.2003

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
L-leucine binding proteins; Escherichia coli; urea-induced unfolding; 5-fluorotryptophan labeling; fluorine (F-19) NMR; fluorescence spectroscopy

Sažetak
Two L-leucine binding proteins of E. coli with overlapping specificities for branched chain amino acids are found in the periplasmic space. There they serve as the first receptors for transport across the membrane. Structurally they have two domains that are open when ligand is not present. Binding of ligand induces a conformational change to a closed form, which is recognized by the membrane complex. There has been a growing interest in these proteins since they have been used as structural models for several neuronal proteins including the Group I metabotrophic glutamate receptors and the N-methyl-D-aspartate receptor. Our laboratory has found that the 'so called' branched amino acid receptors are much more promiscuous in their binding capacities. The L-leucine specific protein has been shown to bind L-phenylalanine and fluoro derivatives of phenylalanine, which are similar in structure to the agonists and antagonists of the glutamate receptors. There may be more similarities in these two families of receptors than was first postulated. We have investigated the unfolding pathways of the two leucine binding proteins of E. coli in urea by intrinsic fluorescence. Thermodynamic stabilities have been determined using a three state model that interprets the unfolding curve. Using site directed mutagenesis of each tryptophan residue we have been able to determine the pathway of unfolding of these two domain proteins. In addition, 5-fluorotryptophan labeled proteins have allowed F-19 NMR spectroscopy to further corroborate our unfolding pathways.

Izvorni jezik
Engleski

Znanstvena područja
Biologija

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