| Summary: In this study, it was aimed to identify the transcriptional classes of Invertebrate iridescent virus 6 (IIV6) genes, detect the conserved regions that could act as promoters in the upstream regions of the genes and investigate the protein(s) that initiate the transcription of the immediate early genes. In the study firstly, the transcription classes of 159 genes of IIV6 genes that have not been classified at transcriptional level to date were determined by RT-PCR technique. It was determined that 114 of these genes belong to immediate early (IE), 23 of them belong to delayed early (DE) and 22 of them belong to late (L) gene classes. Secondly, 200 nucleotide upstream regions, starting from translation initiation site, of all IIV6 genes were analyzed using the MEME Suite database in terms of the conserved region that could act as promoter. TAAAATTGAA motif was determined for IE genes, TTTTATGG for DE genes, TCAATTTT and NNTTGT motifs were determined for L genes. The deletion of these motifs for the IE and DE genes showed a significant decrease in promoter activity, whereas a significant increase in L genes. Site-directed mutagenesis studies showed that the NNTTGT motif in L genes acts as a suppressor on the transcription of the gene, and that a region of a certain length rather than a specific motif can act as a promoter for L gene. Finally, the structural protein(s) required for the virus to initiate infection in the host cell were investigated. The investigation was performed using southwestern, co-transfection, DNA affinity chromatography and bioinformatic analysis. Results showed that a possible protein complex, not a single protein, was involved in the initiation of IIV6 IE gene transcription. One of the possible proteins involved in this complex was found to be 366R with a strong DNA binding domain of about 13,5 kDa.
Keywords: Iridovirus, RT-PCR, Transcription, Promoter, Transactivator |
