Characterization of a new multigene family encoding isomaltases in the yeast Saccharomyces cerevisiae, the IMA family
Authors: Jean-Luc Parrou
Jean Marie François
Marie-Ange Teste
Journal: Journal of Biological Chemistry (2010)
Discipline: BIOLOGY & BIOCHEMISTRY
Keywords: yeast; Saccharomyces cerevisiae; alpha-methylglucopyranoside; isomaltose; genes
Affiliations: CNRS, UMR5504, F-31400 Toulouse.

Abstract:  It has been known for a long time that the yeast Saccharomyces cerevisiae can assimilate alpha-methylglucopyranoside and isomaltose. We here report the identification of 5 genes (YGR287c, YIL172c, YJL216c, YJL221c and YOL157c), which, similar to the SUCx, MALx, or HXTx multigene families, are located in the subtelomeric regions of different chromosomes. They share high nucleotide sequence identities between themselves (66-100%) and with the MALx2 genes (63-74%). Comparison of their amino acid sequences underlined a substitution of threonine by valine in region II, one of the four highly conserved regions of the alpha-glucosidase family. This change was previously shown to be sufficient to discriminate alpha-1,4- to alpha-1,6-glucosidase activity in YGR287c (Yamamoto, K., Nakayama, A., Yamamoto, Y., and Tabata, S. (2004) Eur. J. Biochem. 271, 3414-3420). We showed that each of these five genes encodes a protein with alpha-glucosidase activity on isomaltose, and we therefore renamed these genes IMA1 to IMA5 for IsoMAltase. Our results also illustrated that sequence polymorphisms among this family led to interesting variability of gene expression patterns and of catalytic efficiencies on different substrates, which altogether should account for the absence of functional redundancy for growth on isomaltose. Indeed, deletion studies revealed that IMA1/YGR287c encodes the major isomaltase and that growth on isomaltose required the presence of AGT1, which encodes an alpha-glucoside transporter. Expressions of IMA1 and IMA5/YJL216c were strongly induced by maltose, isomaltose, and alpha-methylglucopyranoside, in accordance with their regulation by the Malx3p-transcription system. The physiological relevance of this IMAx multigene family in S. cerevisiae is discussed. 

Retracted: No

PubPeer comments:
 Figure 3A and Figure 4 u2013 more similar than expected, could authors check it please? ![file] , 
 #1 Dear reader, first, thanks for letting readers and us informed of that unfortunate mistake. The above-mentioned mistake probably resulted from the numerous changes that were performed in the last steps while publishing this work. Indeed, as mentioned in the addendum written at the end of the manuscript, [u201cWhile this work was under the revision process and submitted to SGD for Gene Name Reservation, the SGD curators warned us about an in-press publication from another group in which this set of genes was also named IMA. To avoid a very confusing situation, we agreed to change the numbering system in this report to correspond to the nomenclature found in Naumoffu2019s work (Naumoff, D. G., and Naumov, G. I. (2010) Doklady Biochem. Biophys. 432, 114u2013116) ]. We therefore had to u2018reorganiseu2018 all pictures and figures, as our initial IMA1-5 naming had to fit with the new IMA1-5 assignments. We probably introduced this mistake while preparing these last modifications. We sincerely apologize for that. From a scientific view, IMA3 and IMA4 genes are strictly identical. The first versions of the manuscript did present only one of the two deletion strains; Ima3 delta appeared later in the figures (see below the figure from an earlier version of the manuscript, where ima3 mutant is not there and where the order the strains is different). ![file] Due to the rules of confinement resulting today from the COVID-19 pandemy, we canu2019t get access to lab book archives to check the chronology in getting these results, as well as the exact origin the pictures that were taken and finally used in formatted figures (below a view of the folder with raw data that was just retrieved in archives, yet unexploitable without lab books). We will try to clarify this problem as soon as we can. We will in the future greatly appreciate speaking with identified, concerned persons, not with pseudo. Yours sincerely, Jean-Luc Parrou ![file] ,