1
The Saccharomyces cerevisiae vacuolar acid trehalase is targeted at the cell surface for its physiological function.
FEBS J. 2009 Oct; 276(19):5432-46
All selected articles haveThis article has been added to your saved articles
You can follow/unfollow articles via MyF1000 or via the article or browse pages.
14 Jan 2010
Carlos Gancedo
F1000 Microbiology
Instituto de Investigaciones Biomédicas Alberto Sols,
Madrid, Spain.
F1000 Microbiology
Instituto de Investigaciones Biomédicas Alberto Sols,
Madrid, Spain.
New Finding
DOI: 10.3410/f.1443958.922056
In this paper, acid trehalase (Ath1) was found to be localized at the cell surface in Saccharomyces cerevisiae. This localization appears to explain logically how this enzyme initiates trehalose metabolism in yeast.
Trehalose metabolism in yeast is initiated by its splitting into two molecules of glucose....Continue reading
Trehalose metabolism in yeast is initiated by its splitting into two molecules of glucose....Continue reading
In this paper, acid trehalase (Ath1) was found to be localized at the cell surface in Saccharomyces cerevisiae. This localization appears to explain logically how this enzyme initiates trehalose metabolism in yeast.
Trehalose metabolism in yeast is initiated by its splitting into two molecules of glucose. The enzyme responsible for this reaction is Ath1, whose localization has been reported to be vacuolar. Now, using ATH1 fusions with fluorescent proteins GFP or mCherry integrated in the chromosome and expressed from the ATH1 promoter, the authors found a fluorescent signal not only in the vacuole but also at the cell surface. A SUC2 gene (encoding a sucrose hydrolyzing enzyme) lacking the coding region for the signal peptide of invertase was fused to a full length ATH1 gene. Expression of this fusion allowed growth on sucrose of a mutant, supporting an external localization for Ath1. The 131 amino acid N-terminal fragment of Ath1 was necessary for efficient protein secretion; deletion of this fragment led to an exclusive vacuolar localization of acid trehalase as seen by fluorescence microscopy. In a vps4 mutant impaired in the vacuolar sorting pathway, the fluorescence of an Ath1-mCherry fusion was not observed in the vacuole and could be seen at the cell periphery; growth on trehalose was not impaired, indicating that the vacuolar localization is not necessary for growth in this sugar. Other authors using Ath1-Gfp fusions did not observe fluorescence at the cell periphery {1}. Two possibilities may account for the discrepancy: the use of a strong promoter to express the fusion and the use of different carbon sources in the growth medium. The acid trehalase of Kluyveromyces lactis and that of Candida albicans appear to be localized at the cell surface {2,3}.
This article appears to provide a logical explanation for the function of acid trehalase in trehalose metabolism in Saccharomyces cerevisiae. The question remains open, however, about the physiological role, if any, of the acid trehalase found in the vacuole.
Trehalose metabolism in yeast is initiated by its splitting into two molecules of glucose. The enzyme responsible for this reaction is Ath1, whose localization has been reported to be vacuolar. Now, using ATH1 fusions with fluorescent proteins GFP or mCherry integrated in the chromosome and expressed from the ATH1 promoter, the authors found a fluorescent signal not only in the vacuole but also at the cell surface. A SUC2 gene (encoding a sucrose hydrolyzing enzyme) lacking the coding region for the signal peptide of invertase was fused to a full length ATH1 gene. Expression of this fusion allowed growth on sucrose of a mutant, supporting an external localization for Ath1. The 131 amino acid N-terminal fragment of Ath1 was necessary for efficient protein secretion; deletion of this fragment led to an exclusive vacuolar localization of acid trehalase as seen by fluorescence microscopy. In a vps4 mutant impaired in the vacuolar sorting pathway, the fluorescence of an Ath1-mCherry fusion was not observed in the vacuole and could be seen at the cell periphery; growth on trehalose was not impaired, indicating that the vacuolar localization is not necessary for growth in this sugar. Other authors using Ath1-Gfp fusions did not observe fluorescence at the cell periphery {1}. Two possibilities may account for the discrepancy: the use of a strong promoter to express the fusion and the use of different carbon sources in the growth medium. The acid trehalase of Kluyveromyces lactis and that of Candida albicans appear to be localized at the cell surface {2,3}.
This article appears to provide a logical explanation for the function of acid trehalase in trehalose metabolism in Saccharomyces cerevisiae. The question remains open, however, about the physiological role, if any, of the acid trehalase found in the vacuole.
References
1.
The transmembrane domain of acid trehalase mediates ubiquitin-independent multivesicular body pathway sorting.
Mol Biol Cell 2007 Jul; 7(18):2511-24
PMID: 17475771
2.
Physical and computational analysis of the yeast Kluyveromyces lactis secreted proteome.
Proteomics 2008 Jul; 13(8):2714-23
PMID: 18601269
3.
The ATC1 gene encodes a cell wall-linked acid trehalase required for growth on trehalose in Candida albicans.
J Biol Chem 2004 Sep 24; 39(279):40852-60
PMID: 15252058
Disclosures
One of the authors of the evaluated article has performed some metabolite measurements for Carlos Gancedo. He will not be an author in the resulting paper, which is on a topic unrelated to the evaluated paper.
Add Comment
Gancedo C: F1000Prime Recommendation of [He S et al., FEBS J 2009, 276(19):5432-46]. In F1000Prime, 14 Jan 2010; DOI: 10.3410/f.1443958.922056. F1000Prime.com/1443958#eval922056
F1000Prime Recommendations, Dissents and Comments for [He S et al., FEBS J 2009, 276(19):5432-46]. In F1000Prime, 22 May 2013; F1000Prime.com/1443958
Only registered/signed-in users can make comments.
Sign in or Subscribe to create your user account and join the discussion.
Sign in or Subscribe to create your user account and join the discussion.
No comments yet.
Previous studies in the yeast Saccharomyces cerevisiae have proposed a vacuolar localization for Ath1, which is difficult to reconcile with its ability to hydrolyze exogenous trehalose. We used fluorescent microscopy to show that the red fluorescent protein mCherry fused to the C-terminus of Ath1, although mostly localized in the vacuole, was also targeted to the cell surface. Also, hybrid Ath1 truncates fused at their C-terminus with the yeast internal invertase revealed that a 131 amino acid N-terminal fragment of Ath1was sufficient to target the fusion protein to the cell surface, enabling growth of the suc2Delta mutant on sucrose. The unique transmembrane domain appeared to be indispensable for the production of a functional Ath1, and its removal abrogated invertase secretion and growth on sucrose. Finally, the physiological significance of the cell-surface localization of Ath1 was established by showing that fusion of the signal peptide of invertase to N-terminal truncated Ath1 allowed the ath1Delta mutant to grow on trehalose, whereas the signal sequence of the vacuolar-targeted Pep4 constrained Ath1 in the vacuole and prevented growth of this mutant on trehalose. Use of trafficking mutants that impaired Ath1 delivery to the vacuole abrogated neither its activity nor its growth on exogenous trehalose.
DOI: 10.1111/j.1742-4658.2009.07227.x
PMID: 19703229
