FLOCCULATION OF KLUYVEROMYCES-MARXIANUS IS INDUCED BY A TEMPERATURE UPSHIFT

An upshift of the growth temperature from 26 to 40-degrees-C in the pr esence of calcium leads to the aggregation of Kluyveromyces marxianus cells and to the formation of flocs. Analysis of cell wall proteins, e ither by sodium dodecyl sulphate-polyacrylamide gel electrophoresis of extractable mannoproteins or by immunolocalization. revealed an accum ulation of a protein with Mr 37 kDa (p37), upon flocculation. Immunolo gical studies confirmed the homology of this protein with the glycolyt ic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH). When mRNA isolated from cells growing at 40-degrees-C was translated in vitro, a 35 kDa newly labelled protein was synthesized and immunoprecipitation assays showed that this protein is recognized by p37-antiserum, sugge sting that the 35 kDa polypeptide might be an unglycosylated precursor form of p37. The results indicated that the presence of this cell wal l mannoprotein closely related to GAPDH is dependent on the growth tem perature, suggesting its role as adhesin.