Mitchell F. Balish
CAS Faculty Spotlight
What I enjoy most about teaching is when students just 'get it' …when I see a student's eyes open up, I get very excited!
Ph.D., Emory University, 1998
A commonly expressed but erroneous notion is that the organization of all bacterial cells is simple. In reality, as appreciation of bacterial diversity has increased, it has become apparent that a substantial number of bacteria are quite complex at the cellular level. Microbiologists and cell biologists have supplanted the dogma that was dominant as recently as twenty years ago with an understanding that bacterial cells of all varieties contain cytoskeletons, proteinaceous structures that control cell shape, cell division, and subcellular organization. These cellular features are interesting potential targets for future drug development.
- Mycoplasma pneumoniae cells. Arrows indicate attachment organelles on two of the cells.
- A pair of Mycoplasma penetrans cells dividing. The white area shows the DNA, which is excluded from the attachment organelles, indicated by the arrowheads.
- Cytoskeletal elements of Mycoplasma insons, which lives in iguanas.
- Cytoskeletal elements of the attachment organelles of Mycoplasma penetrans. Each of the smaller objects is approximately the same size as the DNA-free area in panel B.
Of particular interest with regard to cytoskeletal organization and function are the mycoplasmas, a variety of bacteria that predominantly infect vertebrates, including humans, often causing significant diseases. Mycoplasmas lack cell walls and have distinctly small genomes and small cell size. Although mycoplasma infections are treatable with a limited array of antibiotics, worldwide antibiotic resistance of mycoplasmas of humans and animals is ascendant. In the face of rising antibiotic resistance, the development of new treatments for mycoplasmal diseases will surely rely on a deeper understanding of the basic biology of these unusual organisms, including their unique cytoskeletons. Although some mycoplasma cells are organizationally simple, many, through the courtesy of their cytoskeletons, have prominent polar protrusions called attachment organelles. Among those species that have attachment organelles, they are generally essential for attachment to host cells (cytadherence). Attachment organelles are also used for gliding motility of mycoplasma cells along surfaces, and through gliding motility, they contribute to cell division.
How the components of attachment organelles specifically function in the architecture, motility, and virulence-related properties of these structures is largely unknown. The cytoskeletal proteins that are essential for the construction of attachment organelles are found only in mycoplasmas, frustrating efforts to understand these proteins through comparison with model organisms. Furthermore, and even more remarkably, different groups of mycoplasmas use entirely different proteins to create these structures, and they use fundamentally different mechanisms to power gliding motility, suggesting convergent evolution of attachment organelles.
The focus of the research in the Balish lab is elucidation of the molecular underpinnings of mycoplasma virulence, with special attention to attachment organelle morphology, cell division, cytadherence, and gliding motility. Among the species studied in the Balish lab are: Mycoplasma pneumoniae, a leading cause of tracheobronchitis and atypical ("walking") pneumonia, especially in children and young adults, also linked to asthma, autoimmune diseases, and central nervous system infections; Mycoplasma penetrans, an opportunist that colonizes immunocompromised individuals, including HIV-infected patients, in whom it might contribute to morbidity and progression of AIDS; and Mycoplasma iowae, a poultry pathogen.
Techniques used in the Balish lab include molecular biology, protein biochemistry, genomics, time-lapse microcinematographic imaging, and fluorescence and electron microscopy. The Balish lab is currently funded by the National Institutes of Health.
- Identification and characterization of attachment organelle components of Mycoplasma penetrans.
- Development of a genetic system for studying virulence factors and attachment organelle biology of Mycoplasma iowae and Mycoplasma penetrans.
- Determination of the roles of specific components of the attachment organelle of Mycoplasma pneumoniae.
- Comparative genomics of mycoplasma species.
- Physiological and molecular studies of mycoplasma morphogenesis and virulence.
- Understanding Mycoplasma pneumoniae chromosome segregation.
- Pritchard, R.E.*, and M.F. Balish. 2015. Mycoplasma iowae: relationships among oxygen, virulence, and protection from oxidative stress. Vet. Res. 46:36.
- Pritchard, R.E.*, A.J. Prassinos**, J.D. Osborne, Z. Raviv, and M.F. Balish. 2014. Reduction of hydrogen peroxide accumulation and toxicity by a catalase from Mycoplasma iowae. PLoS ONE 9:e105188.
- Jurkovic, D.A.*, M.R. Hughes, and M.F. Balish. 2013. Analysis of energy sources for Mycoplasma penetrans gliding motility. FEMS Microbiol. Lett. 338:39-45.
- Jurkovic, D.A.*, J.T. Newman**, and M.F. Balish. 2012. Conserved terminal organelle morphology in Mycoplasma penetrans and Mycoplasma iowae. J. Bacteriol. 194:2877-2883.
- Relich, R.F.*, and M.F. Balish. 2011. Insights into the function of Mycoplasma pneumoniae protein P30 from orthologous gene replacement. Microbiology 157:2862-2870.
- Relich, R.F.*, A.J. Friedberg**, and M.F. Balish. 2009. Novel cellular organization in a gliding mycoplasma, Mycoplasma insons. J. Bacteriol. 191:5312-5314.
- Hatchel, J.M.*, and M.F. Balish. 2008. Attachment organelle ultrastructure correlates with phylogeny, not gliding motility properties, in Mycoplasma pneumoniae relatives. Microbiology 154:286-295.
- Hatchel, J.M.*, R.S. Balish, M.L. Duley, and M.F. Balish. 2006. Ultrastructure and gliding motility of Mycoplasma amphoriforme, a possible human respiratory pathogen. Microbiology 152:2181-2189.
*: graduate student
**: undergraduate researcher
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