Naslov
Exploring the role of amino acid-18 of the leucine binding proteins of E. coli

Autori
Salopek-Sondi, Branka ; Swartz, Derrick ; Adams, Pamela S. ; Luck, Linda A.

Izvornik
Journal of Biomolecular Structure and Dynamics (0739-1102) 20 (2002), 3; 381-387

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
F-19 NMR; leucine-binding protein; fluorescence; periplasmic binding protein

Sažetak
Two periplasmic binding proteins of E. coli, the leucine specific-binding protein (LS) and the leucine-isoleucine-valine binding protein (LIV), have high similarity in their structure and function, but show different substrate specificity. A key difference between these proteins is residue 18 in the binding pocket, a tryptophan residue in LS and a tyrosine residue in LIV. To examine the role of this residue in binding specificity, we used fluorescence and F-19 NMR to monitor ligand binding to three mutants: LSW18Y, LSW18F and LIV18W. We observed leucine binding to all proteins. LS binds L-phenylalanine but the mutation from Trp to Tyr or Phe disallows this ligand and expands the binding repertoire to L-isoleucine and L-valine. The LIVY18W mutant still retains the ability to bind L-isoleucine and also binds L-phenylalanine.

Izvorni jezik
Engleski

Znanstvena područja
Biologija

POVEZANOST RADA