Research Interests:
Research combines two main interests: viruses and proteins. We study the complex bacteriophage T4 and its simpler cousin phage T7, which have been of enduring interests to molecular biologists since this field was born some 45 years ago. There are four experimental lines we are currently pursuing:
1) The development of a pulse-chase protocol that will reveal the entire assembly pathway in vivo. This is an ambitious project that promises to resolve some of the most difficult unanswered problems in virus morphogenesis. It will provide us with the precise time of addition of each protein and also give us the first quantitative measure of each protein's intracellular pool size.
2) We are also studying head expansion, an important step in head morphogenesis. As the DNA enters the empty head shell, the shell expands 15% in dimension and 50% in volume. We are trying to identify the initiator of expansion and the mechanism by which it is transmitted from one end of the capsid to the other.
3) The structure of the T4 baseplate. We have carried out cross-linking experiments which have permitted the mapping of most of the 15 proteins that make up the baseplate at the bottom of the T4 tall. Its central hub, however, remains an enigma, for it failed to give many contacts and has long been the most difficult subassembly to isolate and work with. We have cloned two of the genes which two groups have shown to be in, or not to be In, the central hub. We plan to now Investigate whether they are In the finished structure and what role they play In baseplate and hub morphogenesis.
Special Responsibilities/Interests /Expertise:
Coordinator of Biology- Chemistry Program
Recent Publications:
Ferguson, P.F., and D.H. Coombs. 2000. Pulse-chase analysis of the in vivo assembly pathway of the bacteriophage T4 tail. J. Mol. Biol. 297:99-117.
Jardine, P. J., McCormick, Agnew Lutze-Wallace and D. H. Coombs. 1998. The bacteriophage T4 DNA packaging apparatus targets the unexpanded prohead. J. Mol. Biol. 284:647-59.
Jardine, P. J. and D. H. Coombs. 1998. Capsid expansion follows the initiation of DNA packaging in bacteriophage T4. J. Mol. Biol. 284: 661-72.
Ferguson, P.F., and D.H. Coombs. 1997. Identification of bacteriophage T4 virion proteins by transverse pore-gradient SDS polyacrylamide gel electrophoresis and dual amino acid labelling. Electrophoresis 18: 2119-2125.
Chen, Mathews, Wheeler, Maley, Maley and Coombs. 1995. An Immunoblot Assay reveals that Bacteriophage T4 Thymidylate Synthetase and Dihydrofolate Reductase are not virion proteins. J. Virology 69:2119-25.
Graduate Students;
Michelle Wang, MSc. : Michelle is currently disecting the T7 assembly pathway with a newly developed Pulse-only protocol.
Meng Zhang, MSc. : Meng is incorporating His-tagged baseplate proteins into phage particles to probe their location and conformation in the particle and their fate during infection.
Positions Available:
One PhD or MSc student position is open. Please
contact Dr. Coombs for more information.
e-mail to: dhc@unb.ca
Maintained by: casey@unb.ca
Last Update: 25 November 2002
This document: http://www.unb.ca/web/Biology/Faculty/Coombs.html