title: Twintrons are not unique to the Euglena chloroplast genome: structure and evolution of a plastome cpn60 gene from a cryptomonad.
abstract: Introns within introns (twintrons) are known only from the Euglena chloroplast genome. Twintrons are group II or III introns, into which another group II or III intron has been transposed. In this paper we describe a non-Euglena twintron structure within a plastid-encoded chaperone gene (cpn60) of the cryptomonad alga Pyrenomonas salina. In addition, the evolutionary relationships between members of the Cpn60 protein family are determined. Our findings permit the inclusion of cryptomonad plastomes in phylogenetic studies of intron evolution and present further evidence for the origin of modern plastids from a cyanobacterial ancestor.
authors: Institute of Biology II, Cell Biology, Freiburg, Germany.
authors: U G
authors: UG
authors: Maier
authors: S A
authors: SA
authors: Rensing
authors: G L
authors: GL
authors: Igloi
authors: M
authors: M
authors: Maerz
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D018834:Chaperonin 60 / Q000235:genetics*; D002874:Chromosome Mapping; D016384:Consensus Sequence; D018744:DNA, Plant / Q000737:chemistry; D056890:Eukaryota / Q000235:genetics*; D017343:Genes, Plant; D007438:Introns / Q000235:genetics*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D018087:Plastids / Q000235:genetics*; D013559:Symbiosis
chemical_list: D018834:Chaperonin 60; D018744:DNA, Plant