title: Extensive structural conservation exists among several homologs of two Euglena chloroplast group II introns.
abstract: 82 of the 155 chloroplast introns in Euglena gracilis have been categorized as group II introns. Because they are shorter and more divergent than group II introns from other organisms, the assignment of these Euglena introns to the group II class has been questioned. In the current study, two homologs of E. gracilis petB intron 1 and four homologs of psbC intron 2 have been isolated from related species and characterized. Based on a comparative sequence analysis of intron homologs, the intron core and four of the six helical domains present in the canonical group II intron structural model are conserved in E. gracilis petB intron 1 and psbC intron 2 and all of their homologs. Distal portions of domain I, which are involved in most of the tertiary interactions, are less well conserved than the central core.
authors.affiliation: Department of Biochemistry, University of Arizona, Tucson, USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Thompson
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.forename: L
authors.initials: L
authors.lastname: Hong
authors.forename: R B
authors.initials: RB
authors.lastname: Hallick
mesh_terms: D000818:Animals; D001483:Base Sequence; D002736:Chloroplasts / Q000235:genetics*; D017124:Conserved Sequence; D005055:Euglena / Q000235:genetics*; D007438:Introns; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics; D045332:Photosystem II Protein Complex; D010940:Plant Proteins / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
chemical_list: C104657:PetB protein, plant; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; C083100:photosystem II, chlorophyll binding protein, CP-43