Associate Professor of Biology
B.S. - James Madison University
Courses: Viral Discovery (BIO 203/ISAT 165), Viral Genome and Bioinformatics (BIO 204/ISAT 166), Genomics (BIO 481)
Bacteriophages (phages) are viruses that infect bacteria. Because they kill bacterial cells, phages and the genes found in their genomes are of great interest as potential clinical and diagnostic tools. Their fascinating structure, usefulness as genetic tools, and important role in the world's microbial ecosystems, coupled with their safe, inexpensive, and simple cultivation in the laboratory have made them ideal subjects for biologists for decades. Phages are thought to be the most numerous organisms on the earth, and analysis of the relatively small number of completely sequenced phage genomes suggests that the global population of phages is rich in genetic diversity. A small number of phages have been studied genetically and biochemically in great detail, but these represent a vanishingly small proportion of the global population. Furthermore, it is unclear whether much of what is known about the few well characterized phages is generally applicable to the much larger number of uncharacterized phages. However, recent advances in DNA sequencing technology have made it possible for several labs to determine the complete genomic sequences of about 400 phages. Thus, the stage is set for a new era of phage biology--one in which genomics plays a central role.
My lab studies phages that infect Mycobacterium smegmatis, a fast-growing, non-pathogenic soil bacterium related to the human pathogen Mycobacterium tuberculosis. We are developing and using bioinformatics tools that help us to understand the unusual way that bacteriophage genomes are organized. This software also aids in identifying phage genes that are peculiar for various reasons, allowing us to hypothesize about their particular function or role within the infectious cycle of the phage. Such genes are then subjected to experimental approaches to test and refine our hypotheses. For example, recent bioinformatics work has identified several phage genes that may be members of a novel type of mobile genetic element, and experiments are being designed to test this prediction.
There are opportunities available in my lab for student collaborators to pursue either microbiology- or bioinformatics-based projects. The microbiology projects utilize standard techniques from the fields of genetics, biochemistry and molecular biology to test predictions about gene function. Alternatively, the bioinformatics projects involve computer programming in the Python programming language in a Linux environment.
Temple, L., Cresawn, S., and Monroe. J. (2010) Genomics and Bioinformatics in undergraduate curricula: Contexts for hybrid lab/lecture courses for entering and advanced science students. Biochemistry and Molecular Biology Education. 38: 23-28.
Stewart CR, Casjens SR, Cresawn SG, Houtz JM, Smith AL, Ford ME, Peebles CL, Hatfull GF, Hendrix RW, Huang WM, Pedulla ML. (2009) The genome of Bacillus subtilis bacteriophage SPO1. J Mol Biol. 388: 48-70.
Turner PC, Dilling BP, Prins C, Cresawn SG, Moyer RW, Condit RC. (2007) Vaccinia virus temperature-sensitive mutants in the A28 gene produce non-infectious virions that bind to cells but are defective in entry. Virology. May 10.
Cresawn SG, Condit RC. (2007) A targeted approach to identification of vaccinia virus postreplicative transcription elongation factors: genetic evidence for a role of the H5R gene in vaccinia transcription. Virology. 363: 333-41.
Cresawn SG, Prins C, Latner DR, Condit RC. (2007) Mapping and phenotypic analysis of spontaneous isatin-beta-thiosemicarbazone resistant mutants of vaccinia virus. Virology 363: 319-32.
Hanauer DI, Jacobs-Sera D, Pedulla ML, Cresawn SG, Hendrix RW, Hatfull GF. (2006) Inquiry learning. Teaching scientific inquiry. Science. 314: 1880-1.
Pitcher RS, Tonkin LM, Daley JM, Palmbos PL, Green AJ, Velting TL, Brzostek A, Korycka-Machala M, Cresawn S, Dziadek J, Hatfull GF, Wilson TE, Doherty AJ. (2006) Mycobacteriophage exploit NHEJ to facilitate genome circularization. Mol Cell. 23: 743-8.