Sherwood Casjens
Professor of pathology
B.S. Michigan State University
Ph.D. Stanford University
Research
This laboratory is studying two areas of prokaryotic molecular biology: (a) the assembly and DNA packaging of dsDNA bacteriophages and (b) chromosome structure and function in Borrelia burgdorferi, the bacteria that causes Lyme disease.
Our work on the bacteriophage problem has focused on phages lambda and P22. These viruses assemble protein precursor particles (the procapsids) first, and then insert the DNA chromosome into these preformed containers. Our work on these phages has concentrated on understanding the translational control of the expression of the genes whose products are involved in these processes and on dissection of the mechanism by which specific DNAs are recognized and inserted into the procapsids. We are using both genetic and biochemical approaches to determine the specific roles of the several proteins involved in the DNA packaging process.
The second area of study is focused on the genome of the Lyme disease spirochete. We and others have recently found that members of the Borrelia genus have a linear chromosomes. All other well characterized bacteria have circular chromosomes. We are currently characterizing the chromosome ends, and are interested in the handling of the ends by the replication machinery.
References
1. Lander G, Tang L, Casjens S, Gilcrease E, Prevelige P, Poliakov A, Potter C, Carragher B, Johnson J (2006) A protein sensor for headful viral chromosome packaging is activated by spooled dsDNA. Science 312:1791-1795
2. Tang L, Gilcrease E, Casjens S, Johnson J (2006) Highly discriminatory binding of capsid cementing proteins in bacteriophage L. Structure 14:837-846
3. Olia A, Al-Bassam J, Winn-Stapley DA, Joss L, Casjens S, Cingolani G (2006) Binding-induced stabilization and assembly of the phage P22 tail accessory factor gp4. J. Mol. Biol. 363:558-576
4. Weigele P, Sampson L, Winn-Stapley D, Casjens S (2005) Molecular genetics of bacteriophage P22 scaffolding protein's functional domains. J. Mol. Biol. 348:831-844
5. Huang W, Robertson M, Aron J, Casjens S (2004) Telomere exchange between linear replicons of Borrelia burgdorferi. J. Bacteriol. 186:4134-4141
6. Gilcrease E, Winn-Stapley D, Hewitt FC, Joss L, Casjens S (2005) Bacteriophage L head assembly gene cluster nucleotide sequence and decoration protein characterization. J. Bacteriol. 187:2050-2057
7. Qiu W, Schutzer S, Bruno J, Attie O, Xu J, Dunn J, Fraser C, Casjens S, Luft B (2004) Recombination and plasmid transfer among Borrelia burgdorferi sensu stricto lineages revealed by three-way genome comparisons and multi-locus sequence typing. Proc. Natl. Acad. Sci., USA 101:14150-14155
8. Casjens S (2003) Prophages in sequenced bacterial genomes: what have we learned so far? Molec. Microbiol. 49:277-300
9. Wu H, Sampson L, Parr R, Casjens S (2002) The DNA site utilized by bacteriophage P22 for initiation of DNA packaging. Molec. Microbiol. 45:1631-1646
10. Casjens S, Palmer N, van Vugt R, Huang WM, et al. (2000) A genome in flux: The twelve linear and nine circular extrachromosomal DNAs of an infectious isolate of the Lyme disease spirochete Borrelia burgdorferi. Molec. Microbiol. 35:490-516
11. Palmer N, Fraser C, Casjens S (2000) Distribution of twelve linear extrachromosomal DNAs among natural isolates of the Lyme disease spirochete Borrelia burgdorferi. J. Bacteriol. 182:2476-2480
