The site-specific ribosomal DNA insertion element R1Bm belongs to a class of non-long-terminal-repeat retrotransposons

Journal Article · Fri Jan 01 00:00:00 EST 1988 · Mol. Cell. Biol.; (United States)

DOI:https://doi.org/10.1128/MCB.8.1.114· OSTI ID:6924582

Xiong, Y; Eickbush, T H

Two types of insertion elements, R1 and R2 (previously called type I and type II), are known to interrupt the 28S ribosomal genes of several insect species. In the silkmoth, Bombyx mori, each element occupies approximately 10% of the estimated 240 ribosomal DNA units, while at most only a few copies are located outside the ribosomal DNA units. The authors present here the complete nucleotide sequence of an R1 insertion from B. mori (R1Bm). This 5.1-kilobase element contains two overlapping open reading frames (ORFs) which together occupy 88% of its length. ORF1 is 461 amino acids in length and exhibits characteristics of retroviral gag genes. ORF2 is 1,051 amino acids in length and contains homology to reverse transcriptase-like enzymes. The analysis of 3' and 5' ends of independent isolates from the ribosomal locus supports the suggestion that R1 is still functioning as a transposable element. The precise location of the element within the genome implies that its transposition must occur with remarkable insertion sequence specificity. Comparison of the deduced amino acid sequences from six retrotransposons, R1 and R2 of B. mori, I factor and F element of Drosophila melanogaster, L1 of Mus domesticus, and Ingi of Trypanosoma brucei, reveals a relatively high level of sequence homology in the reverse transcriptase region. Like R1, these elements lack long terminal repeats. The authors therefore named this class of related elements the non-long-terminal-repeat (non-LTR) retrotransposons.

• Research Organization: Dept. of Biology, River Campus, Univ. of Rochester, Rochester, NY (US)
• OSTI ID: 6924582
• Journal Information: Mol. Cell. Biol.; (United States), Vol. 8:1
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
RIBOSOMAL RNA
DNA SEQUENCING
GENE REGULATION
GENES
RNA PROCESSING
SILKWORM
GENETIC MAPPING
TRANSPOSONS
AMINO ACID SEQUENCE
DROSOPHILA
ENDONUCLEASES
ENZYME ACTIVITY
NUCLEOPROTEINS
TRANSCRIPTION
TRYPANOSOMA
VIRUSES
ANIMALS
ARTHROPODS
DIPTERA
DNA-ASE
ENZYMES
ESTERASES
FLIES
FRUIT FLIES
HYDROLASES
INSECTS
INVERTEBRATES
LEPIDOPTERA
MAPPING
MASTIGOPHORA
MICROORGANISMS
MOLECULAR STRUCTURE
MOTHS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PARASITES
PHOSPHODIESTERASES
PROTEINS
RNA
STRUCTURAL CHEMICAL ANALYSIS
550400* - Genetics