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Characterization of AGT1 encoding a general α‐glucoside transporter from Saccharomyces
Author(s) -
Han EunKyoung,
Cotty Francis,
Sottas Chantal,
Jiang Hua,
Michels Corinne A.
Publication year - 1995
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1995.mmi_17061093.x
Subject(s) - lactose permease , maltotriose , biology , maltose , isomaltose , symporter , saccharomyces cerevisiae , biochemistry , gene , permease , genetics , microbiology and biotechnology , transporter , enzyme
Molecular genetic analysis is used to characterize the AGT1 gene encoding an α‐glucoside transporter. AGT1 is found in many Saccharomyces cerevisiae laboratory strains and maps to a naturally occurring, partially functional allele of the MAL1 locus. Agt1p is a highly hydrophobic, postulated integral membrane protein. It is 57% identical to Mal61p, the maltose permease encoded at MAL6 , and is also a member of the 12 transmembrane domain superfamily of sugar transporters. Like Mal61p, Agt1p is a high‐affinity, maltose/proton symporter, but Mal61p is capable of transporting only maltose and turanose, while Agt1p transports these two α‐glucosides as well as several others including isomaltose, α‐methylglucoside, maltotriose, palatinose, trehalose and melezitose. AGT1 expression is maltose inducible and induction is mediated by the Mal‐activator. The sequence of the upstream region of AGT1 is identical to that of the maltose‐inducible MAL61 gene over a 469 bp region containing the UAS MAL but the 315 bp sequence immediately upstream of AGT1 shows no significant homology to the sequence immediately upstream of MAL61 . The evolutionary origin of the MAL1 allele to which AGT1 maps and the relationship of AGT1 to other α‐glucoside fermentation genes is discussed.