Conservation of sequence and function of the pag-3 genes from C-elegans and C-briggsae

The Caenorhabditis briggsae homologue of the Caenorhabditis elegans pag-3 g ene was cloned and sequenced. When transformed into a C. elegans pag-3 muta nt, the C. briggsae pag-3 gene rescued the pag-3 reverse kinker and letharg ic phenotypes. The C. elegans pag-3 gene fused to lacZ was expressed in the same pattern in C. elegans and C. briggsae. Unlike many gene homologues co mpared between C. elegans and C. briggsae, extensive sequence conservation was found in the non-coding regions upstream of the pag-3 exons, in several of the introns and in the downstream non-coding region. Furthermore, the s plice acceptor and splice donor sites were conserved, and the size of the i ntrons and exons was surprisingly similar. The predicted protein sequence o f C. briggsae PAG-3 was 85% identical to the protein sequence of C. elegans PAG-3. Because so much of the non-coding region of pag-3 was conserved, th e control of pag-3 may be quite complex, involving the binding of many tran s-acting factors. These results suggest the evolutionary conservation of th e pag-3 gene sequence, its expression and function. (C) 2000 Elsevier Scien ce B.V. All rights reserved.