DNA-storing and ejection from Chlorella viruses
Zusammenfassung der Projektergebnisse
Chlorella viruses enclose in their capside a large dsDNA genome and large number of proteins; some proteins are present in one particle with copy numbers > 2,000. When infection of an algal host cell fails the viral DNA and its proteins are in many cases ejected from the capsid; as a result the particle is catapult in a straight line with a velocity of about 2 µm/ s away from the host. Because the DNA is densely packaged in the particle the force, which is generated by the expansion of the DNA, can in a successful infection aid in the transfer of the genome into the host. An estimate of this force with Stoke’s law from the velocity of DNA ejection implies that it is in the same order of magnitude as the remaining turgor pressure of the host. Hence the ejection force seems sufficient for transferring at least parts of the viral genome into the host. Imaging of ejected viral DNA indicates that it is intimately associated with proteins in a periodic fashion. The bulk of the protein particles detected in atomic force micrographs have a size of ~70 kDa and two proteins of about this size are among 6 basic putative DNA binding proteins found in a proteomic analysis of DNA binding proteins. A combination of fluorescence images of ejected DNA and a bioinformatics analysis reveal periodic patterns in the viral DNA. The periodic distribution of GC rich regions in the genome provides potential binding sites for basic proteins. This specific DNA/protein aggregation, which can be confirmed by AFM force measurements, could be responsible for the periodic concentration of fluorescently labeled DNA observed in ejected viral DNA. Collectively the data indicate that the large chlorella viruses have a DNA packaging strategy that differs from phages; it involves proteins and shares similarities to that of chromatin structure in eukaryotes.
Projektbezogene Publikationen (Auswahl)
- (2012) Structural organization of DNA in Chlorella viruses. PLoSOne. 7:e30133
Wulfmeyer, T. Polzer, C. Hiepler, G., Hamacher, K., Shoeman, R., Dunigan, D. van Etten, J.L., Lolicato, M., Moroni, A., Thiel, G., Meckel, T.
(Siehe online unter https://doi.org/10.1371/journal.pone.0030133) - Interaction of DNA and proteins in virus PBCV-1 particles. Structural organization of DNA in Chlorella viruses, Dissertation 2012, Technische Universität Darmstadt
Wulfmeyer, T.
- (2013) Chlorovirus attachment to the host cell wall is reversible. Abstract American Soc. Virology
Agarkova, I., Hertel, B., Zhang, X., Dunigan, D., Rossmann, M., Thiel, G. van Etten, J.
