DNA Packaging and Host Cell Lysis : Late Events in Bacteriophage PRD1 Infection

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http://urn.fi/URN:ISBN:978-952-10-5022-0
Title: DNA Packaging and Host Cell Lysis : Late Events in Bacteriophage PRD1 Infection
Author: Ziedaite, Gabija
Contributor: University of Helsinki, Faculty of Biosciences, Department of Biological and Environmental Sciences, General Microbiology
Institute of Biotechnology
Publisher: Helsingin yliopisto
Date: 2008-11-07
Language: en
Belongs to series: Dissertationes bioscientiarum molecularium Universitatis Helsingiensis in Viikki - URN:ISSN:1795-7079
URI: http://urn.fi/URN:ISBN:978-952-10-5022-0
http://hdl.handle.net/10138/21967
Thesis level: Doctoral dissertation (article-based)
Abstract: The object of this study is a tailless internal membrane-containing bacteriophage PRD1. It has a dsDNA genome with covalently bound terminal proteins required for replication. The uniqueness of the structure makes this phage a desirable object of research. PRD1 has been studied for some 30 years during which time a lot of information has accumulated on its structure and life-cycle. The two least characterised steps of the PRD1 life-cycle, the genome packaging and virus release are investigated here. PRD1 shares the main principles of virion assembly (DNA packaging in particular) and host cell lysis with other dsDNA bacteriophages. However, this phage has some fascinating individual peculiarities, such as DNA packaging into a membrane vesicle inside the capsid, absence of apparent portal protein, holin inhibitor and procapsid expansion. In the course of this study we have identified the components of the DNA packaging vertex of the capsid, and determined the function of protein P6 in packaging. We managed to purify the procapsids for an in vitro packaging system, optimise the reaction and significantly increase its efficiency. We developed a new method to determine DNA translocation and were able to quantify the efficiency and the rate of packaging. A model for PRD1 DNA packaging was also proposed. Another part of this study covers the lysis of the host cell. As other dsDNA bacteriophages PRD1 has been proposed to utilise a two-component lysis system. The existence of this lysis system in PRD1 has been proven by experiments using recombinant proteins and the multi-step nature of the lysis process has been established.DNA:n pakkaus ja isäntäsolun hajotus: Bakteriofaagi PRD1 -infektion loppuvaiheen tapahtumat Virukset ovat solunsisäisiä loisia, jotka käyttävät hyväkseen isäntäsolunsa resursseja tuottaakseen uusia viruskopioita. Tämän tutkimuksen kohteena on eräs bakteereja infektoiva virus, PRD1. PRD1:n rakenne on bakteerivirukseksi poikkeuksellinen, ja se on osittain samankaltainen adenoviruksen kanssa. Työssä on keskitytty PRD1:n elinkierron kahteen viimeiseen vaiheeseen: viruksen genomin pakkaamiseen ja isäntäsolun hajotukseen. Viruksen perimäaineksen, pitkän DNA- tai RNA-molekyylin, pakkaaminen tiukasti hyvin pieneen, suojaavaan proteiinikuoreen eli kapsidiin edelleen kuljetettavaksi seuraavaan kohteeseen on kiehtova prosessi. Tässä työssä on tutkittu PRD1:n perimäaineksen eli genomin pakkaamista kapsidiin. Kun viruksen genomi on monistettu solussa ja uudet viruspartikkelit on koottu, on niiden päästävä ulos solusta infektoimaan uusia isäntäsoluja. Tässä työssä on selvitetty, miten ja milloin PRD1-infektiossa isäntäsolu hajotetaan uusien viruksien vapauttamiseksi. Toivon mukaan tämä väitöskirjatyö voi omalta osaltaan tuoda lisävalaistusta käsityksiimme näistä bakteerivirusten perustavanlaatuisista prosesseista.
Subject: yleinen mikrobiologia
Rights: This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited.


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