Office: R325 Research Building.
Tel: (314) 516-4146
B.S., Cellular and Molecular Biology, 1993, Tulane University, New Orleans, LA.
Ph.D., Microbiology and Molecular Genetics, 2000, Harvard University, Cambridge, MA.
Post-doctoral fellow, 2000-2005, Cornell University, Ithaca, NY.
The work in my lab focuses on the molecular mechanisms underlying bacterial infection of higher organisms. Our bacterium of choice for these studies is Pseudomonas syringae
, a gram-negative pathogen that causes disease in many vegetable, fruit, and grain crops. When infecting plants, P. syringae
colonizes the apoplast, or the space in between plant cells. Intruders in this location often induce plant defense mechanisms that prevent pathogens from growing and spreading to other host cells. To counteract these plant defenses, P. syringae
possesses its own arsenal of biological weapons. One such weapon is its type III secretion system (T3SS), a protein export apparatus that delivers virulence proteins directly into plant cells. The P. syringae
type III secretion apparatus is encoded by a cluster of 25 genes, and mutations in many of these genes severely reduce virulence in host plants. The proteins translocated into plants by the P. syringae
T3SS are called Hops or Avrs. We estimate that the P. syringae
T3SS delivers 33 different Hop/Avr proteins into plant cells during infection. Although the functions of most Hops/Avrs are unknown, some of them appear to suppress the activation of defense responses in host plants. Our main goal is to understand how P. syringae
employs the T3SS and secreted proteins to colonize plant tissue. We are also interested in identifying other protein export systems that are involved in modulating interactions with plants or even insects.
Schechter, L.M., Vencato, M., Jordan, K.L., Schneider, S.E., Schneider, D.J., and Collmer, A. In press. Multiple approaches to a complete inventory of Pseudomonas syringae pv. tomato
DC3000 type III secretion system effector proteins. Mol Plant-Microbe Interact
Rojas, C.M., Ham, J.H., Schechter, L.M., Kim, J.F., Beer, S.V., and Collmer, A. (2004) The Erwinia chrysanthemi EC16 hrp/hrc gene cluster encodes an active Hrp type III secretion system that is flanked by virulence genes functionally unrelated to the Hrp system. Mol Plant-Microbe Interact 17: 644-653.
Schechter, L.M., Roberts, K.A., Jamir, Y., Alfano, J.R., and Collmer, A. (2004) Pseudomonas syringae type III secretion system targeting signals and novel effectors studied with a Cya translocation reporter. J Bacteriol 186: 543-555.
Petnicki-Ocwieja T., Schneider D.J., Tam V.C., Chancey S.T., Shan L., Jamir Y., Schechter L.M., Janes M.D., Buell C.R., Tang X., Collmer A., Alfano J.R. (2002) Genomewide identification of proteins secreted by the Hrp type III protein secretion system of Pseudomonas syringae pv. tomato DC3000. Proc Natl Acad Sci U S A 99: 7652-7657.