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Office: (859) 323-5147
Fax: (859) 257-8994
Lab: (859) 323-3870
Email: jjo222@uky.edu
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Jason Johnston, Ph.D.
Assistant Professor
Doctoral Studies: University of Alabama at Birmingham.
Postdoctoral: University of Iowa.
Research Statement:
My laboratory studies gene regulation and virulence in nontypeable Heamophilus influenzae (NTHi) and Streptococcus pneumoniae. Both organisms are opportunistic pathogens that are commonly found as normal flora in the upper airways of adults. We study the transcriptional regulation to allow for the identification of genes required for virulence, and then determine their role in infection and host-pathogen interactions. We use a wide variety of genetic, biochemical, and physiological methods in the course of our investigations.
Our work in NTHi focuses on biofilm formation, an important feature in middle ear infections. We are studying a cell-cell communication system that is responsible for signaling between biofilm and free-living planktonic cells. Inactivation of this system attenuates biofilm formation in an animal infection model. We also study the regulation of sialic acid acquisition and catabolism, an important surface component required for the evasion of the host innate immune response.
Studies in S. pneumoniae have focused on Mn2+-dependent regulation of virulence factors and the role of Mn2+ transport in virulence. PsaR, a Mn2+-responsive transcriptional factor regulates a number of surface proteins. Also, Mn2+ acquisition affects adherence in a PsaR-independent manner, indicating that other mechanisms of Mn2+-dependent regulation may exist. Mn2+ is also required for the defense against the oxidative response produced by the host immune system.
Selected Recent Publications:
Johnston, J. W., N. P. Coussens, S. Allen, J. Houtman, K. H. Turner, A. Zaleski, S. Ramaswamy, B. W. Gibson, and M. A. Apicella. 2008. Characterization of the N-acetyl-5-neuraminic acid binding site of the extracytoplasmic solute receptor (SiaP) of nontypeable Haemophilus influenzae strain 2019. J. Biol. Chem. 283: 855-865.
Johnston, J. W., A. Zaleski, S. Allen, J. M. Mootz, D. Armbruster, B. W. Gibson, M. A. Apicella, and R. S. Munson, Jr. 2007. Regulation of sialic acid transport and catabolism in Haemophilus influenzae. Mol. Microbiol. 66: 26-39.
Johnston, J. W., D. E. Briles, L. E. Myers, and S. K. Hollingshead. 2006. Mn2+-dependent regulation of multiple genes in Streptococcus pneumoniae through PsaR and the resultant impact on virulence. Infect. Immun. 74: 1171-1180.
Allen, S., A. Zaleski, J. W. Johnston, B. W. Gibson, and M. A. Apicella. 2005. Novel sialic acid transporter of Haemophilus influenzae. Infect. Immun. 73: 5291-5300.
Johnston, J. W., L. E. Myers, M. M. Oochs, W. H. Benjamin, Jr., D. E. Briles, and S. K. Hollingshead. 2004. Lipoprotein PsaA in virulence of Streptococcus pneumoniae: surface accessibility and role in protection from superoxide. Infect. Immun. 72: 5858-5867.
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