How and why does the plant pathogen Agrobacterium tumefaciens elongate only from one end of the cell? Does this usual mode of growth impact microbe-host interactions? We aim to better understand this unusual mode of growth in hopes of contributing to efforts to combat important plant and animal pathogens.

My lab is interested in understanding the principles that govern bacterial morphology, a readily observable facet of microbial cell biology. One of the major unsolved questions in microbiology is how bacteria generate specific shapes. Bacteria exhibit an amazing diversity of shapes and sizes that are precisely reproduced at every generation, indicating that morphology plays an important role in the life of these bacteria. Impressive progress has been made in the past few years in understanding the mechanism of cell shape determination in a few model bacterial systems, including the discovery that bacteria possess a cytoskeleton, but we are still very far having a comprehensive understanding of how bacterial morphologies are generated. My lab takes advantage of recent technical advances in microscopy, construction of fluorescent fusion proteins, and high throughput sequencing, to make strides in understanding how bacteria generate specific morphologies.

In most bacteria, the cell wall is comprised of peptidoglycan and is a major determinant of cell shape. In a majority of rod-shaped bacteria, including E. coli, cells elongate by the lateral insertion of newly synthesized peptidoglycan along their sidewalls. In contrast, some rod-shaped bacteria utilize precise targeting of peptidoglycan to specific polar locations to enable cell elongation. Indeed, have previously shown that constrained polar growth is responsible for elongation in many species of Rhizobiales. My lab uses Agrobacterium tumefaciens, a well-studied plant pathogen and causative agent of crown gall disease, as a model to understand how bacteria constrain peptidoglycan synthesis to specific cellular localizations. Presently, we are focused on addressing two key questions:

What is the mechanism underlying polar growth of A. tumefaciens?

What are the ecological and evolutionary benefits imparted by polar growth?

Knowledge gained though these studies will then be applied to enhance our understanding of the precisely targeted growth in other Alphaproteobacteria, including those that display remarkable morphologies. Our goal is to better understand the role of zonal peptidoglycan synthesis in generating both relatively simple and dramatically complex bacterial shapes.

• Divisional Council, Division of Biological Sciences (2012-2014)
• Graduate Education Committee, Division of Biological Sciences (2012 - 2013)
• Advisory Board Member for Framing Your Future: A Science Career Conference, University of Missouri (2012 - 2013)
• Reviewer, PLoS ONE (2011 – present)
• Reviewer, Journal of Bacteriology (2009 – present)
• Member, Committee for Postdoctoral Affairs, Indiana University (2008-2009)
• Student/Post-doc Committee Member, Microbial Biochemistry Faculty Search, Indiana University (2008)
• Ruth L. Kirschstein National Research Service Award Postdoctoral Fellowship (AI072992) (2007 – 2010)
• University of Georgia Outstanding Graduate Research in Life Sciences Award (2006)
• American Society for Microbiology Graduate Student Travel Grant (2005)
• Judge in Medicine and Health, Georgia State Science and Engineering Fair (2005)
• University of Georgia Outstanding Teaching Assistant Award (2004)
• Joy Williams Porter Graduate Fellowship Recipient (for outstanding research, teaching, and service) (2003)
• UGA Microbiology Graduate Student Association Team Member, ACS Relay for Life (2002-2005)
• Abstract Reviewer, CURO (Center for Undergraduate Research Opportunities) (2002-2005)
• Symposium Convener, CURO (2003-2005)
• ARCS (Acheivement Rewards for College Scientists) Fellowship Recipient (2002 – 2005)
• President, UGA Microbiology Graduate Student Association (2002-2003)
• American Society for Microbiology Graduate Student Travel Grant (2002)
• Faculty Liaison, UGA Microbiology Graduate Student Association (2001-2002)
• University of Georgia Presidential Fellow (one of twelve in all disciplines) (2000 – 2005)
• Member, American Society for Microbiology (2000-present)

Kuru E, Hughes HV, Brown PJ, Hall E, Tekkam S, Cava F, de Pedro MA, Brun YV, Vannieuwenhze MS. In Situ Probing of Newly Synthesized Peptidoglycan in Live Bacteria with Fluorescent D-Amino Acids. Angew Chem Int Ed Engl. 2012 Oct 10.doi: 10.1002/anie.201206749.

Madren SM, Hoffman MD, Brown PJ, Kysela DT, Brun YV, Jacobson SC. Microfluidic device for automated synchronization of bacterial cells. Anal Chem. 2012 Oct 16;84(20):8571-8. doi: 10.1021/ac301565g.

Chertkov O, Brown PJ, Kysela DT, de Pedro MA, Lucas S, Copeland A, Lapidus A, Del Rio TG, Tice H, Bruce D, Goodwin L, Pitluck S, Detter JC, Han C, Larimer F,Chang YJ, Jeffries CD, Land M, Hauser L, Kyrpides NC, Ivanova N, Ovchinnikova G, Tindall BJ, Göker M, Klenk HP, Brun YV. Complete genome sequence of Hirschiabaltica type strain (IFAM 1418(T)). Stand Genomic Sci. 2011 Dec 31;5(3):287-97.

Pejaver VR, An J, Rhee S, Bhan A, Choi JH, Liu B, Lee H, Brown PJ, Kysela D, Brun YV, Kim S. GeneclusterViz: a tool for conserved gene cluster visualization, exploration and analysis. Bioinformatics. 2012 Jun 1;28(11):1527-9. Epub 2012 Apr 11.

Brown PJ, de Pedro MA, Kysela DT, Van der Henst C, Kim J, De Bolle X, Fuqua C, Brun YV. Polar growth in the Alphaproteobacterial order Rhizobiales. Proc Natl Acad Sci U S A. 2012 Jan 31;109(5):1697-701.

Li G, Brown PJ, Tang JX, Xu J, Quardokus EM, Fuqua C, Brun YV. Surface contact stimulates the just-in-time deployment of bacterial adhesins. Mol Microbiol. 2012 Jan;83(1):41-51. .

Brown PJ, Kysela DT, Brun YV. Polarity and the diversity of growth mechanisms in bacteria. Semin Cell Dev Biol. 2011 Oct;22(8):790-8. Review.

Brown PJ, Kysela DT, Buechlein A, Hemmerich C, Brun YV. Genome sequences of eight morphologically diverse Alphaproteobacteria. J Bacteriol. 2011 Sep;193(17):4567-8.

Kovarik ML, Brown PJ, Kysela DT, Berne C, Kinsella AC, Brun YV, Jacobson SC. Microchannel-nanopore device for bacterial chemotaxis assays. Anal Chem. 2010 Nov15;82(22):9357-64.

Hardy GG, Allen RC, Toh E, Long M, Brown PJ, Cole-Tobian JL, Brun YV. A localized multimeric anchor attaches the Caulobacter holdfast to the cell pole. Mol Microbiol. 2010 Apr;76(2):409-27.

Brown PJ, Hardy GG, Trimble MJ, Brun YV. Complex regulatory pathways coordinate cell-cycle progression and development in Caulobacter crescentus. Adv Microb Physiol. 2009;54:1-101. Review.

Bonner PJ, Black WP, Yang Z, Shimkets LJ. FibA and PilA act cooperatively during fruiting body formation of Myxococcus xanthus. Mol Microbiol. 2006 Sep;61(5):1283-93.

Bonner PJ, Shimkets LJ. Phospholipid directed motility of surface-motile bacteria. Mol Microbiol. 2006 Sep;61(5):1101-9. Review.

Bonner PJ, Shimkets LJ. Cohesion-defective mutants of Myxococcus xanthus. J Bacteriol. 2006 Jun;188(12):4585-8.

Bonner PJ, Xu Q, Black WP, Li Z, Yang Z, Shimkets LJ. The Dif chemosensory pathway is directly involved in phosphatidylethanolamine sensory transduction in Myxococcus xanthus. Mol Microbiol. 2005 Sep;57(5):1499-508.

Kearns DB, Bonner PJ, Smith DR, Shimkets LJ. An extracellular matrix-associated zinc metalloprotease is required for dilauroyl phosphatidylethanolamine chemotactic excitation in Myxococcus xanthus. J Bacteriol. 2002 Mar;184(6):1678-84.

Kearns DB, Venot A, Bonner PJ, Stevens B, Boons GJ, Shimkets LJ. Identification of a developmental chemoattractant in Myxococcus xanthus through metabolic engineering. Proc Natl Acad Sci U S A. 2001 Nov 20;98(24):13990-4.

Bonner PJ, Shimkets LJ. Piecing together a puzzling pathway: new insights into C-signaling. Trends Microbiol. 2001 Oct;9(10):462-4. Review.