Characterization of the unique intron - exon junctions of euglena gene(s) encoding the polyprotein precursor to the light-harvesting chlorophyll a/b binding protein of photosystem II


The precursor to the Euglena light harvesting chlorophyll a/b binding protein of photosystem II (LHCPII) Is a polyprotein containing multiple copies of LHCPII covalently joined by a decapeptlde linker. cDNA and genomic clones encoding the 5' and 3' end of a 6.6 kb LHCPII mRNA were sequenced. A 3.1 kb genomic region encoding 1.05 kb of the 5' end of LHCPII mRNA contains 4 introns. A 7.6 kb genomic region encoding 3.3 kb of the 3' end of LHCPII mRNA contains 10 Introns. The 5' and 3' ends of the 14 Identified Euglena Introns lacked the conserved dlnucleotldes (5'-GT and AG-3') found at the termini of virtually every characterized nuclear pre-mRNA Intron. A common consensus splice site selection sequence could not be identified. The Euglena Introns do not have the structural characteristics of group I and group II Introns. The only structural feature common to all Euglena Introns was the ability of short stretches of nudeotldes at the 5' and 3' ends of the Introns to base pair, forming a stable stem-loop with the 5' and 3' splice site juxtaposed for splicing but displaced by 2 nudeotldes. The 26 nucleotlde sequence at the 5' end of LHCPII mRNA Is absent from the genomic sequence and Identical to the 5' end of one of the small Euglena SL-RNAs indicating that it is post-transcriptlonally added by frans-spllclng. © 1994 Oxford University Press.

Publication Title

Nucleic Acids Research