In our laboratory, we are trying to establish the relationship between the structure and size of mannoproteins and their effects when they are added in winemaking. For that purpose, we use non-transgenic mutants of S.cerevisiae with defects in mannoproteins synthesis, named mnn (mannan defective). These mutants were obtained by random mutagenesis, but it is unknown the exact mutation in the gene which causes the protein inactivation. So far, it has only been identified in the case of mnn3.
To complete the characterization of mnn mutants, in this study we are sequenced the altered genes in each of them.
MNN1: located at chromosome V (YER001W), 2289 bp. It encodes an integral membrane protein with alpha-1,3-mannosyltransferase activity.
MNN2: located ay chromosome II (YBR015C), 1794 bp. It encodes an integral membrane protein with alpha-1,2-mannosyltransferase activity over mannoses joined by alpha-1,6.
MNN5: located at chromosome V(YJL186W), 1761 bp. It encodes an integral membrane protein with alpha-1,2-mannosyltransferase activity over some mannoses joined by alpha-1,2.
MNN6: located at chromosome XVI (YPL053C), 1341 bp. It encodes an integral membrane protein with mannosylphosphate transferase activity.
MNN9: located at chromosome XVI (YPL050C), 1188 bp. It encodes an integral membrane protein which is part of a complex involved in external chain elongation.
MNN10: located at chromosome IV (YDR245W), 1182 bp. It encodes an integral membrane protein which is part of a complex involved in external chain elongation.
As expected, in most cases are point mutations with different effects: missense mutations, nonsense mutations or frameshift mutations.
In the last few years, the mnn mutants have been widely characterized phenotypically. With this study, the genotypic characterization is completed.
Acknowledgments: Projects GR18117 y IB16132 (Consejería de Economía, Ciencia y Agenda Digital, Junta de Extremadura), project AGL2017-87635-R (Ministerio de Economía, Industria y Competitividad, Agencia Estatal de Investigación, Gobierno de España) and Fondo Europeo de Desarrollo Regional (FEDER).
