TY  - JOUR
A1  - Hutin, Stephanie
A1  - Ling, Wai Li
A1  - Tarbouriech, Nicolas
A1  - Schoehn, Guy
A1  - Grimm, Clemens
A1  - Fischer, Utz
A1  - Burmeister, Wim P.
T1  - The vaccinia virus DNA helicase structure from combined single-particle cryo-electron microscopy and AlphaFold2 prediction
JF  - Viruses
N2  - Poxviruses are large DNA viruses with a linear double-stranded DNA genome circularized at the extremities. The helicase-primase D5, composed of six identical 90 kDa subunits, is required for DNA replication. D5 consists of a primase fragment flexibly attached to the hexameric C-terminal polypeptide (res. 323–785) with confirmed nucleotide hydrolase and DNA-binding activity but an elusive helicase activity. We determined its structure by single-particle cryo-electron microscopy. It displays an AAA+ helicase core flanked by N- and C-terminal domains. Model building was greatly helped by the predicted structure of D5 using AlphaFold2. The 3.9 Å structure of the N-terminal domain forms a well-defined tight ring while the resolution decreases towards the C-terminus, still allowing the fit of the predicted structure. The N-terminal domain is partially present in papillomavirus E1 and polyomavirus LTA helicases, as well as in a bacteriophage NrS-1 helicase domain, which is also closely related to the AAA+ helicase domain of D5. Using the Pfam domain database, a D5_N domain followed by DUF5906 and Pox_D5 domains could be assigned to the cryo-EM structure, providing the first 3D structures for D5_N and Pox_D5 domains. The same domain organization has been identified in a family of putative helicases from large DNA viruses, bacteriophages, and selfish DNA elements.
KW  - DNA replication
KW  - helicase
KW  - Pfam domain
KW  - poxvirus
KW  - cryo-electron microscopy
KW  - structure prediction
KW  - SF3 helicase
KW  - orthopoxvirus
KW  - DNA helicase
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-290523
SN  - 1999-4915
VL  - 14
IS  - 10
ER  - 
TY  - JOUR
A1  - Gassen, Alwine
A1  - Brechtefeld, Doris
A1  - Schandry, Niklas
A1  - Arteaga-Salas, J. Manuel
A1  - Israel, Lars
A1  - Imhof, Axel
A1  - Janzen, Christian J.
T1  - DOT1A-dependent H3K76 methylation is required for replication regulation in Trypanosoma brucei
JF  - Nucleic Acids Research
N2  - Cell-cycle progression requires careful regulation to ensure accurate propagation of genetic material to the daughter cells. Although many cell-cycle regulators are evolutionarily conserved in the protozoan parasite Trypanosoma brucei, novel regulatory mechanisms seem to have evolved. Here, we analyse the function of the histone methyltransferase DOT1A during cell-cycle progression. Over-expression of DOT1A generates a population of cells with aneuploid nuclei as well as enucleated cells. Detailed analysis shows that DOT1A over-expression causes continuous replication of the nuclear DNA. In contrast, depletion of DOT1A by RNAi abolishes replication but does not prevent karyokinesis. As histone H3K76 methylation has never been associated with replication control in eukaryotes before, we have discovered a novel function of DOT1 enzymes, which might not be unique to trypanosomes.
KW  - variants
KW  - cell-cycle regulation
KW  - blood-stream forms
KW  - african trypanosomes
KW  - mammalian cells
KW  - DNA replication
KW  - DOT1
KW  - protein
KW  - transcription
KW  - cultivation
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-131449
VL  - 40
IS  - 20
ER  - 
TY  - JOUR
A1  - Rudel, Thomas
A1  - Prusty, Bhupesh K.
A1  - Siegl, Christine
A1  - Hauck, Petra
A1  - Hain, Johannes
A1  - Korhonen, Suvi J.
A1  - Hiltunen-Back, Eija
A1  - Poulakkainen, Mirja
T1  - Chlamydia trachomatis Infection Induces Replication of Latent HHV-6
JF  - PLoS ONE
N2  - Human herpesvirus-6 (HHV-6) exists in latent form either as a nuclear episome or integrated into human chromosomes in more than 90% of healthy individuals without causing clinical symptoms. Immunosuppression and stress conditions can reactivate HHV-6 replication, associated with clinical complications and even death. We have previously shown that co-infection of Chlamydia trachomatis and HHV-6 promotes chlamydial persistence and increases viral uptake in an in vitro cell culture model. Here we investigated C. trachomatis-induced HHV-6 activation in cell lines and fresh blood samples from patients having Chromosomally integrated HHV-6 (CiHHV-6). We observed activation of latent HHV-6 DNA replication in CiHHV-6 cell lines and fresh blood cells without formation of viral particles. Interestingly, we detected HHV-6 DNA in blood as well as cervical swabs from C. trachomatis-infected women. Low virus titers correlated with high C. trachomatis load and vice versa, demonstrating a potentially significant interaction of these pathogens in blood cells and in the cervix of infected patients. Our data suggest a thus far underestimated interference of HHV-6 and C. trachomatis with a likely impact on the disease outcome as consequence of co-infection.
KW  - blood
KW  - chlamydia
KW  - chlamydia infection
KW  - chlamydia trachomatis
KW  - DNA replication
KW  - macrophages
KW  - polymerase chain reaction
KW  - viral load
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-96731
ER  -