Solid-state NMR spectroscopy reveals anomer specific transport of galactose in the milk yeast Kluyveromyces lactis

• Published in: FEMS yeast research Vol. 12; no. 4; pp. 415 - 422
• Main Authors: Fukasawa, Toshio, Abe, Akio, Nakamura, Atsusi, Horigome, Miyako, Naito, Akira
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.06.2012; Oxford University Press
• Subjects: aldose‐1‐epimerase; anomeric conversion; Biological Transport; Carbohydrate Epimerases - genetics; Epimerase; GAL/LAC induction; Galactose; Galactose - chemistry; Galactose - metabolism; Gene Deletion; Glucose transporter; Isomerism; Kluyveromyces - chemistry; Kluyveromyces - enzymology; Kluyveromyces - genetics; Kluyveromyces - metabolism; Kluyveromyces lactis; Magnetic fields; Magnetic Resonance Spectroscopy; minor mutarotase; Mutants; NMR; Nuclear magnetic resonance; Spectrum analysis; sugar transporter; UDP‐galactose; Yeast; UDP-galactose; minor mutarotase; anomeric conversion; induction; sugar transporter; aldose-1-epimerase
• ISSN: 1567-1356; 1567-1364
• DOI: 10.1111/j.1567-1364.2012.00788.x

Abstract Genetic evidence indicates that only the β-anomer of galactose is transported to Kluyveromyces lactis cells by galactose/glucose transporter Hgt1p, and that aldose-1-epimerase encoded by GAL10 is a prerequisite for growth on galactose. Minor aldose-1-epimerases other than Gal10p also exist in K. lactis. Using a mutant defective in both aldose-1-epimerases, we show by solid-state nuclear magnetic resonance spectroscopy that only β-anomer is transported in the cell and stays without or with a slow rate of conversion to α-anomer. Signals due to intracellular β-galactose appeared at two positions, both of which were shifted towards higher magnetic fields than that of β-galactose in aqueous solution, suggesting that incorporated galactose binds to cellular components, probably proteins.