EMB-5, A GENE REQUIRED FOR THE CORRECT TIMING OF GUT PRECURSOR CELL-DIVISION DURING GASTRULATION IN CAENORHABDITIS-ELEGANS, ENCODES A PROTEIN SIMILAR TO THE YEAST NUCLEAR-PROTEIN SPT6

The emb-5 gene is required for the correct timing of division of gut p recursor cells during gastrulation in Caenorhabditis elegans. We have now characterized the molecular structure of emb-5. The predicted emb- 5-encoded protein (EMB-5) possesses an extremely acidic amino-terminus and overall similarity to the Saccharomyces cerevisiae nuclear protei n SPT6, which has been shown to affect the transcription of a variety of genes and suggested to play a role in chromatin assembly or modific ation. EMB-5 may function in the control of cell cycle timing by modul ating chromatin structure and consequently affects morphogenesis of C. elegans.