Ffz1, a new transporter specific for fructose from Zygosaccharomyces bailii

Abstract

The basis of fructophily in the yeast Zygosaccharomyces bailii has been shown to reside in the performance of transport systems for hexoses. In this study, a gene encoding a fructose-specific transporter was characterized. The strategy involved the functional complementation of a Saccharomyces cerevisiae strain that does not take up hexoses (hxt-null strain). This strain was transformed with a genomic library of Z. bailii. One transformant capable of growing on fructose, but not on glucose, was obtained. This transformant did not transport D-[14 C]glucose, and the kinetic parameters for D-[ 14 C]fructose were V max =3?3 mmol h "1 g "1 and K m =80?4 mM. As in the original strain of Z. bailii, fructose uptake was not inhibited by the presence of other hexoses or uranyl. The plasmid responsible for the observed phenotype was found to carry an ORF encoding a 616 amino acid protein with the characteristics of a membrane transporter, which was designated FFZ1 (fructose facilitator Zygosaccharomyces). The impairment in function observed in an S. cerevisiae transformant expressing a truncated Ffz1 protein lacking 67 amino acids at the C-terminus suggests an important role for this terminal part in the proper structure of the transporter.

The osmotolerant fructophilic yeast Zygosaccharomyces rouxii employs two plasma-membrane fructose uptake systems belonging to a new family of yeast sugar transporters

“…In these two Zygosaccharomyces species, fructose transport is thus prioritised over that of glucose, mainly at high sugar concentrations, since: (i) the transport system specific for fructose has a high capacity; (ii) fructose competes with glucose for the hexose transport system; and (iii) high concentrations of fructose inactivate the glucose facilitator (Sousa-Dias et al, 1996; S. Sousa-Dias and M. C. Loureiro-Dias, unpublished results). similarity to previously characterized sugar transporters (Pina et al, 2004).…”

“…T suggested the existence of a lowaffinity high-capacity transporter specific for fructose (S. Sousa-Dias and M. C. Loureiro-Dias, unpublished results), similar to the one already characterized in Z. bailii (Pina et al, 2004). We used the sequence of Z. bailii Ffz1 to search the Z. rouxii Génolevures genome database (Sherman et al, 2009) When compared with the protein sequences of known sugar transporters of other yeasts and fungi, the three Zygosaccharomyces proteins seem to form a protein subfamily apparently unrelated to other known and wellcharacterized yeast hexose transporters of the SP family (Fig.…”

“…Results from one of two independent experiments are shown. fructose transport is not affected by 1 mM uranyl nitrate (Sousa-Dias et al, 1996) and neither is heterologously expressed ZbFfz1 inhibited by uranyl cations (Pina et al, 2004).…”

Occurrence of FFZ genes in yeasts and correlation with fructophilic behaviour

“…bailii and Zs. rouxii a peculiar type of fructose transporter designated Ffz (Fructose facilitator Zygosaccharomyces) was characterized at the molecular level: a fructose-specific facilitator Ffz1 [Zb Ffz1 (Pina et al, 2004) and Zr Ffz1 (Leandro et al, 2011)] and a Zr Ffz2 that transports fructose and glucose with similar capacity and affinity (Leandro et al, 2011). In the recently sequenced genome of Zs.…”

The High-Capacity Specific Fructose Facilitator ZrFfz1 Is Essential for the Fructophilic Behavior of Zygosaccharomyces rouxii CBS 732T

“…The Z. bailii Ffz1 (ZbFfz1) protein, when expressed in a hxt-null mutant of S. cerevisiae, behaved as a high-capacity and low-affinity (K m , ϳ80 mM; V max , ϳ3 mmol h Ϫ1 g Ϫ1 ) specific fructose facilitator with low protein sequence identity to the sugar porter family (12). Two similar proteins, Z. rouxii Ffz1 (ZrFfz1) (a fructose-specific facilitator; K m , ϳ400 mM; V max , ϳ13 mmol h Ϫ1 g Ϫ1 ) and ZrFfz2 (a fructose/glucose facilitator; K m glucose; fructose , ϳ200 mM; V max glucose; fructose , ϳ4 mmol h Ϫ1 g Ϫ1 ), were subsequently characterized in Z. rouxii CBS 732 T , revealing the existence of a new family of sugar transporters (13).…”