Carbon source activation of protein synthesis during germination of Neurospora crassa conidia: Two-dimensional gel analysis of [ 35S]methioinine-labeled polypeptides

Abstract

The two-dimensional gel patterns of polypeptides synthesized by spores incubated for 1 hour in minimal medium or in sucrose-only medium are very similar. Approximately 98% of the labeled polypeptides synthesized by spores incubated in minimal medium are also synthesized in spores incubated in sucrose-only medium. Of the remaining 2%, some are synthesized only in spores incubated in minimal medium while others are synthesized only in spores incubated in sucrose-only medium. These results conclusively demonstrate that the carbon source (sucrose) is the key constituent in minimal medium responsible for the normal activation of protein synthesis during the first hour of germination. On the other hand, spores incubated for 3 hours in sucrose-only medium exhibit a highly abnormal two-dimensional gel profile when compared to spores incubated for 3 hours in minimal medium. At this time less than 40% of the labeled polypeptides visualized are common to spores incubated in the two different media. Polypeptides which are not held in common are distributed over a wide range of isoelectric points and molecular weights. These results indicate that prolonged incubation of spores in medium containing only the carbon source results in highly abnormal protein synthesis.