IMV Executive Assistant
tel. (612) 624-1926
fax. (612) 625-1108
18-242 Moos Tower
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Minneapolis, MN 55455
Phone: (612) 624-7989
University of Minnesota, 1961, Ph.D.
Structure and Assembly of Bacteriophage ø29
Bacteriophage ø29 of Bacillus subtilis offers the opportunity for a complete understanding of the structure and assembly of a complex dsDNA bacterial virus in molecular terms. Current goals include uncovering the mechanisms of a) assembly of the viral precursor capsid (prohead) in vitro from purified proteins and a host chaperonin, b) assembly and function of the powerful motor that packages the dsDNA and the mechanochemical energy transduction, c) sequential protein and DNA conformational changes that regulate assembly, and d) tail penetration of the cell wall during infection. Atomic resolution structures of five of eight ø29 structural proteins have been produced, and a complete atomic resolution structure of the virus is within reach.
A sequence of single-particle, asymmetric cryoEM-3D reconstructions of mature and empty virions have been produced in collaborations. A sub-nanometer reconstruction has revealed protein secondary structural elements in situ, rearrangement of connector alpha helices, remodeling of the shell protein where it contacts DNA, and a 60Å diameter DNA toroid in the junction between connector/lower collar that may form as the DNA responds to linear compression.
The mechanochemical cycle of the packaging motor has been probed by the use of laser tweezers single molecule studies in collaboration. Phosphate or ADP release is likely the power stroke of the motor. Use of optical tweezers capable of 1 bp resolution has revealed a highly coordinated motor in which the gp16 ATPase subunits load with ATP during a “dwell”, followed by rapid firings of the subunits to package 10 bp of DNA in a “burst” which consists, surprisingly, of four 2.5-bp steps. Load bearing contacts with phosphates that regulate the chemical cycle take place during the dwell phase every 10-bp on the 5’-3’ strand in the direction of packaging. Strong phosphate contacts hold the DNA in place during the dwell phase, while less specific contacts drive translocation during the burst phase.
The ø29 tail proteins gp13 and gp12* have enzymatic activities, forecasting an understanding of tail penetration of the cell wall in infection. The morphogenetic factor gp13, located at the distal tip of the tail knob, is a Zn2+-D,D-endopeptidase that cleaves the peptide cross-link of the B. subtilis cell wall. Its structure was solved to 1.8Å resolution by X-ray crystallography. An autocatalytic assembly mechanism of the gp12 tail appendages was demonstrated by X-ray crystallography. The gp12 C-terminal domain is an “auto-chaperone” that aids trimerization, and auto-cleavage of the domain is followed by a unique ATP-dependent release. Subsequently, three domains of the N-terminus function in appendage attachment, cell wall digestion, and host binding, respectively.
'Wisc-e-sota', the 1st Joint UMN-UW Virology Training Grant Symposium will be held on Friday, Sepbember 20th, 2013 at the Uniiversity of Wisconsin-La Crosse, Cartwright Center. This is the inaugural collaborative symposium of the NIH T32-supported virology training programs at the University of Wisconsin-Madison and the University of Minnesota-Twin Cities. Talks and poster sessions will be presented by students, postdocs and faculty.
The 2013 IMV Symposium was held in May, 2013 and featured Vincent Racaniello as the Keynote Speaker as well as the recording of an episode of 'This Week in Virology'. Pictures from the IMV Symposium can be found on the IMV Facebook page and a videotape of the TWiV podcast can be viewed at www.twiv.tv
Read about bacteriophage phi 29 and why it matters.
Explore nearly a century's worth of discovery in the field of virology at the University of Minnesota.
"This Week in Virology" from professor Vincent Racaniello.