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 decapeptide 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 dinucleotides (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 nucleotides 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 nucleotides. The 26 nucleotide 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-transcriptionally added by trans-splicing.
School of Biological Sciences, University of Nebraska-Lincoln 68588-0343.
U S
US
Muchhal
S D
SD
Schwartzbach
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D005056:Euglena gracilis / Q000235:genetics*; D015870:Gene Expression; D017343:Genes, Plant; D007438:Introns; D045342:Light-Harvesting Protein Complexes; D008969:Molecular Sequence Data; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics*; D045332:Photosystem II Protein Complex; D010940:Plant Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics
D018076:DNA, Complementary; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D012333:RNA, Messenger