Analysis of the <i>Euglena gracilis</i> chloroplast genome: Fragment <i>Eco-I</i> encodes the gene for the <i>M</i>_r 32 000–33 000 thylakoid protein of photosystem II reaction center

The DNA fragment <i>Eco</i>-I (4700 kilobasepairs) from the circular chloroplast genome of <i>Euglena gracilis</i> is shown to be transcribed in etioplasts at all stages of light-induced plastid development and in fully differentiated chloroplasts. Major stable transcription products are mRNAs of 14S and 17S. Using a rabbit reticulocyte lysate translation system we can show that the fragment <i>Eco</i>-I selects a mRNA which directs the synthesis of a <i>M</i>_r 32 000–33 000 polypeptide. <i>Eco</i>-I also hybridizes with a 330 basepair DNA probe cut from within the spinach chloroplast gene encoding the <i>M</i>_r 32 000 thylakoid membrane protein of the photosystem II reaction center. We conclude that the fragment <i>Eco</i>-I carries the corresponding <i>Euglena gracilis</i> chloroplast gene.