Molecular analysis of the transcripts encoding the light-harvesting chlorophyll a/b protein in Euglena gracilis: unusual size of the mRNA.

A cDNA library made from Euglena polyadenylated RNA has been constructed in the expression vector lambda gt11. The library was screened with antibodies directed against the LHCP apoproteins. Several putative LHCP clones were isolated and analyzed. We present the nucleotide and derived amino-acid sequence of an 800 bp long insert containing a poly A tail. On an amino-acid basis, the Euglena LHCP shows a 60% homology with the corresponding pea gene. Northern blot analysis revealed an unusual size of 7.5 kb. This extremely large mRNA is also recognized by a LHCP probe from Chlamydomonas. Hybrid-selected translation produces 2 proteins of 90-110 kd equivalent in size of the polypeptides immunoprecipitated from the translation products of polyadenylated RNAs.