Transcription of sea urchin histone genes in HeLa cells

HeLa cells were transfected with recombinant DNAs containing the embryonic histone gene repeat of P.miliaris (h22) inserted in either orientation into a pBR-SV40 vector. After 2 to 3 days cytoplasmic RNA was analyzed for authentic sea urchin histone gene transcripts. The correct 5' termini of all five histone genes were detected, three (H2B, H2A and H3) at relatively high levels. In contrast, termination was largely aberrant with the correct 3' terminus of only the H2B mRNA found in significant amounts. The levels of histone gene transcription were dependent on the presence, but not the orientation, of SV40 DNA in the recombinant plasmid. The efficiency of initiation of transcription of the individual sea urchin histone genes in HeLa cells was very similar to that previously observed in Xenopus oocytes. The termination pattern, however, was quite different in that oocytes, all but the H3 gene terminate efficiently. The idiosyncrasies in termination efficiencies for these two heterologous transcription systems may reflect the presence of termination factors which are relatively species or even tissue specific and only some of which recognize the sea urchin "terminators" correctly.