TY - JOUR
T1 - Structural basis for DNA recognition and loading into a viral packaging motor
AU - Buettner, Carina R.
AU - Chechik, Maria
AU - Ortiz-Lombardia, Miguel
AU - Smits, Callum
AU - Ebong, Ima-Obong
AU - Chechik, Victor
AU - Jeschke, Gunnar
AU - Dykeman, Eric
AU - Benini, Stefano
AU - Robinson, Carol V.
AU - Alonso, Juan C.
AU - Antson, Alfred A.
PY - 2012/1/17
Y1 - 2012/1/17
N2 - Genome packaging into preformed viral procapsids is driven by powerful molecular motors. The small terminase protein is essential for the initial recognition of viral DNA and regulates the motor's ATPase and nuclease activities during DNA translocation. The crystal structure of a full-length small terminase protein from the Siphoviridae bacteriophage SF6, comprising the N-terminal DNA binding, the oligomerization core, and the C-terminal beta-barrel domains, reveals a nine-subunit circular assembly in which the DNA-binding domains are arranged around the oligomerization core in a highly flexible manner. Mass spectrometry analysis and four further crystal structures show that, although the full-length protein exclusively forms nine-subunit assemblies, protein constructs missing the C-terminal beta-barrel form both nine-subunit and ten-subunit assemblies, indicating the importance of the C terminus for defining the oligomeric state. The mechanism by which a ring-shaped small terminase oligomer binds viral DNA has not previously been elucidated. Here, we probed binding in vitro by using EPR and surface plasmon resonance experiments, which indicated that interaction with DNA is mediated exclusively by the DNA-binding domains and suggested a nucleosome-like model in which DNA binds around the outside of the protein oligomer.
AB - Genome packaging into preformed viral procapsids is driven by powerful molecular motors. The small terminase protein is essential for the initial recognition of viral DNA and regulates the motor's ATPase and nuclease activities during DNA translocation. The crystal structure of a full-length small terminase protein from the Siphoviridae bacteriophage SF6, comprising the N-terminal DNA binding, the oligomerization core, and the C-terminal beta-barrel domains, reveals a nine-subunit circular assembly in which the DNA-binding domains are arranged around the oligomerization core in a highly flexible manner. Mass spectrometry analysis and four further crystal structures show that, although the full-length protein exclusively forms nine-subunit assemblies, protein constructs missing the C-terminal beta-barrel form both nine-subunit and ten-subunit assemblies, indicating the importance of the C terminus for defining the oligomeric state. The mechanism by which a ring-shaped small terminase oligomer binds viral DNA has not previously been elucidated. Here, we probed binding in vitro by using EPR and surface plasmon resonance experiments, which indicated that interaction with DNA is mediated exclusively by the DNA-binding domains and suggested a nucleosome-like model in which DNA binds around the outside of the protein oligomer.
UR - http://www.scopus.com/inward/record.url?scp=84856373698&partnerID=8YFLogxK
U2 - 10.1073/pnas.1110270109
DO - 10.1073/pnas.1110270109
M3 - Article
VL - 109
SP - 811
EP - 816
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 3
ER -