Department of Biological Sciences

School of Natural Sciences and Mathematics

Faculty and Research

Lee Bulla , Ph.D.

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Education and Professional Affiliations

B.S., Biology and Mathematics, Midwestern State University
Ph.D., Microbiology and Biochemistry, Oregon State University
Member, American Society for Microbiology
Member, American Society of Biochemistry & Molecular Biology


Dr. Bulla’s research interests are in the area of invertebrate and microbial molecular biology with particular focus on the biochemical and biophysical characterization of insecticidal toxin receptors in insects.

Research Interests

Many subspecies of the soil bacterium Bacillus thuringiensis produce various parasporal crystal proteins, also known as Cry toxins, that exhibit insecticidal activity upon binding to specific receptors in the midgut of susceptible insects. One such receptor, BT-R1(210 kDa), is a cadherin located in the midgut epithelium of the tobacco hornworm, Manduca sexta. It has a high binding affinity (Kd~1 nM) for the Cry1A toxins of B. thuringiensis. Truncation analysis of BT-R1 revealed that the only fragment capable of binding the Cry1A toxins of B. thuringiensis is a contiguous 169-amino acid sequence adjacent to the membrane-proximal extracellular domain. The purified toxin-binding fragment acts as an antagonist to Cry1Ab toxin by blocking the binding of toxin to the tobacco hornworm midgut and inhibiting insecticidal action. Exogenous Cry1Ab toxin bound to intact COS-7 cells expressing BT-R1 cDNA, subsequently killing the cells. Recruitment of BT-R1 by B. thuringiensis indicates that the bacterium interacts with a specific cell adhesion molecule during its pathogenesis. Apparently, Cry toxins, like other bacterial toxins, attack epithelial barriers by targeting cell adhesion molecules within susceptible insect hosts.


1. Dorsch, J.A., M. Candas, N.B. Griko, W.S.A. Maaty, E.G. Midboe, , R.K. Vadlamudi and L.A. Bulla, Jr. 2002. Cry1A toxins of Bacillus thuringiensis bind specifically to a region adjacent to the membrane-proximal extracellular domain of BT-R1 in Manduca sexta: involvement of a cadherin in the entomopathogenicity of Bacillus thuringiensis. Insect Biochem. Mol. Biol. 32:1025-1036.

2. Midboe, E.G., M. Candas and L.A. Bulla, Jr. 2003. Expression of a midgutspecific cadherin BT-R1 during the development of Manduca sexta larva. Comp. Biochem. Physiol. 135:125-137.

3. Griko, N., M. Candas, X. Zhang, M. Junker and L.A. Bulla, Jr. 2003. Selective antagonism to the cadherin BT-R1 interferes with calcium-induced adhesion of epithelial membrane vesicles. Biochem. 43:1393-1400.

4. Kakhniashvili, D.G., L.A Bulla, Jr. and S.R. Goodman. 2004. The human erythrocyte proteome: analysis by ion trap mass spectrometry. Mol. Cell. Proteomics. 5:501-509.

  • Updated: February 6, 2006