日時：	2024年6月26日（水 ）16：00～17：30
場所：	京都大学 医生物学研究所　医生研３号館３階セミナー室（312） 3F Seminar room (312), Bldg. #3 of Institute for Life and Medical Sciences (LiMe)
演者：	Dr. Juha Huiskonen　 Director Institute of Biotechnology, University of Helsinki
演題：	Restructuring of bacteriophage ɸ6 viral particle activates semiconservative transcription

講演要旨

Double-stranded RNA viruses transcribe their genome within a proteinaceous viral capsid to avoid host cell defenses. Members of the Reovirales use conservative transcription analogously to cellular gene expression. Most other dsRNA viruses, however, transcribe their genome using semiconservative transcription whereby the positive strand of the genomic template becomes mRNA. Here, we visualize the activation of semi-conservative transcription in ɸ6 cystovirus particles using cryo-EM and Localized Reconstruction method. The tri-segmented dsRNA genome is organized as a spool. Upon transcription initiation, we observe a stepwise assembly of transcription complexes at the opposing poles of the genome spool, in addition to a concomitant expansion of the inner capsid layer and uncoating of the outer capsid layer. We show that the minor protein P7 is essential for transcription. The mature transcription complexes consist of asymmetric dimers of P7 dimers forming a triskelion around the viral polymerases. The polymerases neighbor the vertices of the icosahedral capsid. The packaging hexamers at the vertices channel the viral mRNA exit. Our results define the complex molecular pathway from the quiescent state to the activation of semi-conservative intra-capsid transcription.

 

主催： JSPS 研究拠点形成事業 Core-to-Core Program

「ウイルスの二面性の理解・活用のための国際研究拠点形成」

共同利用・共同研究拠点「ウイルス・幹細胞システム医生物学共同研究拠点」

世話人：京都大学医生物学研究所: ウイルス制御分野 橋口隆生（Tel:075-751-4049）