Interaction between the critical aromatic amino acid residues Tyr352 and Phe504 in the yeast Gal2 transporter

FEBS Letters

Kasahara, Toshiko¹  Kasahara, Michihiro¹ 

[1] Laboratory of Biophysics, School of Medicine, Teikyo University, Hachioji, Tokyo 192-0395, Japan

关键词: Galactose transport;    Gal2;    Hxt2;    Substrate recognition;    Glucose transport;    Aromatic amino acid;    TM;    transmembrane segment;    PCR;    polymerase chain reaction;    GFP;    green fluorescent protein;   

DOI  :  10.1016/S0014-5793(00)01371-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Three critical aromatic sites have been identified in the yeast galactose transporter Gal2: Tyr³⁵² at the extracellular boundary of putative transmembrane segment (TM) 7, Tyr⁴⁴⁶ in the middle of TM10 and Phe⁵⁰⁴ 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 Tyr⁴⁴⁶ 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 (Phe³⁵²Trp⁵⁰⁴ and Trp³⁵²Trp⁵⁰⁴) or no significant activity (Phe³⁵²Tyr⁵⁰⁴ and Trp³⁵²Tyr⁵⁰⁴), whereas single-site mutants showed markedly reduced activity. These results are indicative of a specific interaction between sites 352 and 504 of Gal2.

【 授权许可】

Unknown