title: Identification of the primary structure and the coding capacity of the genome of insect iridescent virus type 6 between the genome coordinates 0.310 and 0.347 (7990 bp).
abstract: The primary structure and the coding capacity of the insect iridescent virus type 6--Chilo iridescent virus (CIV)--were determined between the genome coordinates 0.310 (EcoRI site) and 0.347 (ClaI site). The EcoRI CIV DNA fragment M (7.1 kb; 0.310-0.345 map units) harbors one out of at least six loci of DNA replication origins which is located at nucleotide position 485-513. The identification of the structural properties and the coding capacity of the EcoRI CIV DNA fragment M was carried out by DNA nucleotide sequencing, computer-aided sequence analysis and DNA/RNA hybridization. The EcoRI CIV DNA fragment M (7,099 bp; 71.14% A+T and 28.86% G+C) possesses two clusters of five tandemly organized repetitive DNA elements with complex structural arrangements (R1-R5) which are located between nucleotide positions 3272-3350 and 3403-3414. The analysis of the DNA sequences of the EcoRI CIV DNA fragment M revealed the presence of six open reading frames (ORFs 1-6). Two out of six detected putative proteins are of particular interest. ORF-2 was found to be terminated at nucleotide position 366 (TAA) within the DNA sequence of the EcoRI CIV DNA fragment L (0.345-0.381 map units; 7.4 kb). The analysis of ORF-2 (1,051 amino acids; 120 kD) revealed homologies to several DNA-directed RNA polymerases. ORF-6 encodes a protein (606 amino acids; 69 kD) which is related to a group of yeast, Drosophila and mammalian proteins of a distinct family of putative DNA and/or RNA helicases belonging to the 'DEAD/H' superfamily. The transcriptional activity of the EcoRI CIV DNA fragment M was determined by DNA/RNA hybridization experiments. These analyses revealed the existence of three RNA transcripts of about 3.4 kb (t1), 1.8 kb (t2) and 1.2 kb (t3) which agree with the predicted size of the expected RNA transcripts from ORF-2 (1,051 amino acids; 3.1 kb) and ORF-6 (606 amino acids; 1.8 kb).
authors.affiliation: Institut für Medizinische Virologie, Universität Heidelberg, Germany.
authors.forename: K C
authors.initials: KC
authors.lastname: Sonntag
authors.forename: P
authors.initials: P
authors.lastname: Schnitzler
authors.forename: W
authors.initials: W
authors.lastname: Janssen
authors.forename: G
authors.initials: G
authors.lastname: Darai
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D015246:Deoxyribonuclease EcoRI / Q000378:metabolism; D016679:Genome, Viral; D017994:Iridovirus / Q000737:chemistry* / Q000235:genetics*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016366:Open Reading Frames / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013728:Terminator Regions, Genetic; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics*
chemical_list: D014764:Viral Proteins; D012321:DNA-Directed RNA Polymerases; D015246:Deoxyribonuclease EcoRI