Renilla luciferase as a vital reporter for chloroplast gene expression in Chlamydomonas

The use of luciferases as reporters of gene expression in living cells has been extended to the chloroplast genome. We show that the luciferase from t he soft coral Renilla reniformis (Rluc) can be successfully expressed in th e chloroplast of Chlamydomonas reinhardtii. Expression of the rluc cDNA was driven by the promoter and 5' untranslated regions of the atpA gene. Weste rn analysis with an anti-Rluc antibody detected a single polypeptide of 38 kDa in the luminescent cells. This is 3 kDa larger than native Rluc, and su ggests that translation of the chimeric mRNA begins at the atpA start codon , 29 codons upstream from the rluc start site. We also show that the lumine scence of the transformants was sufficient to enable imaging of colonies us ing a cooled CCD camera.