Nucleus‐encoded <scp>mRNA</scp>s for Chloroplast Proteins <scp>GapA</scp>,<scp> PetA</scp>, and <scp>PsbO</scp> are <i>Trans</i>‐spliced in the Flagellate <i>Euglena gracilis</i> Irrespective of Light and Plastid Function

Abstract

Euglena gracilis is a fresh-water flagellate possessing secondary chloroplasts of green algal origin. In contrast with organisms possessing primary plastids, mRNA levels of nucleus-encoded genes for chloroplast proteins in E. gracilis depend on neither light nor plastid function. However, it remains unknown, if all these mRNAs are trans-spliced and possess spliced leader sequence at the 5'-end and if trans-splicing depends on light or functional plastids. This study revealed that polyadenylated mRNAs encoding the chloroplast proteins glyceraldehyde-3-phosphate dehydrogenase (GapA), cytochrome f (PetA), and subunit O of photosystem II (PsbO) are trans-spliced irrespective of light or plastid function.