Elongation factor 1 alpha genes of the red alga Porphyra purpurea include a novel, developmentally specialized variant

The life cycle of the red alga Porphyra purpurea alternates between two morphologically distinct phases: a shell-boring, filamentous sporophyte and a free-living, foliose gametophyte. From a subtracted cDNA library enriched for sporophyte-specific sequences, we isolated a cDNA encoding an unusual elongation factor 1 alpha (EF-1 alpha) that is expressed only in the sporophyte. A second EF-1 alpha gene that is expressed equally in the sporophyte and the gametophyte was isolated from a genomic library. These are the only EF-1 alpha genes detectable in P. purpurea. The constitutively expressed gene encodes an EF-la very similar to those of most eukaryotes. However, the sporophyte-specific EF-1 alpha is one of the most divergent yet described, with nine insertions or deletions ranging in size from 1 to 26 amino acids. This is the first report of a developmental stage-specific EF-lx outside of the animal kingdom and suggests a fundamental role for EF-1 alpha in the developmental process.