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Interaction between the critical aromatic amino acid residues Tyr 352 and Phe 504 in the yeast Gal2 transporter
Author(s) -
Kasahara Toshiko,
Kasahara Michihiro
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(00)01371-5
Subject(s) - chemistry , aromatic amino acids , galactose , stereochemistry , yeast , transmembrane domain , mutagenesis , transporter , mutant , biochemistry , amino acid , gene
Three critical aromatic sites have been identified in the yeast galactose transporter Gal2: Tyr 352 at the extracellular boundary of putative transmembrane segment (TM) 7, Tyr 446 in the middle of TM10 and Phe 504 in the middle of TM12. The relationship between these sites was investigated by random mutagenesis of each combination of two of the three residues. Galactose transport‐positive clones selected by plate assays encoded Tyr 446 and specific combinations of aromatic residues at sites 352 and 504. Double‐site mutants containing aromatic residues at these latter two positions showed either essentially full galactose transport activity (Phe 352 Trp 504 and Trp 352 Trp 504 ) or no significant activity (Phe 352 Tyr 504 and Trp 352 Tyr 504 ), whereas single‐site mutants showed markedly reduced activity. These results are indicative of a specific interaction between sites 352 and 504 of Gal2.