Book of Abstracts: Albany 2007

category image Albany 2007
Conversation 15
June 19-23 2007

Crystallographic and Biochemical Characterization of the GTPase and Ribosome Binding Properties of Salmonella Typhimuirum BipA

BipA, also known as TypA, is a universally conserved prokaryotic GTPase that is upregulated in response to stress and virulence in strains of globally problematic pathogenic bacteria (1-3). Interestingly, Escherichia coli null bipA bacterial strains are avirulent and so we believe that BipA represents a novel target for antimicrobial development. It was recently demonstrated that BipA is a translational regulator of Fis, a DNA binding protein that operates on multiple levels to facilitate the adaptation of bacteria to their environment (4). Much is to be learned about the global regulatory properties of this protein. As part of an interdisciplinary approach to answer fundamental questions about the mechanism of action of BipA, including its interaction with the ribosome, we have solved the crystal structure of Salmonella typhimurium BipA to 2.5 Å resolution by selenium SAD phasing, with two copies of the protein in the asymmetric unit. In agreement with sequence homology, the first four domains in BipA resemble those previously described for domains I, II, III, and V in the EF-G/EF-2 family of translation factors, whereas the C-terminal domain of BipA is unique. Biochemical studies demonstrate that the ribosome binding determinants of the protein are localized to this region of the protein. Our BipA structure reveals a novel domain arrangement which resembles that suggested by the model of the EF-G/GMP-P(CH2)P/70S complex deduced by cryo-EM (5).

References and Footnotes
  1. Farris, M., Grant, A., Richardson, T. B., and O'Connor, C. D. Molecular Microbiology 28, 265-279 (1998).
  2. Rowe, S., Hodson, N., Griffiths, G., and Roberts, I. S. Journal of Bacteriology 182, 2741-2745 (2000).
  3. Grant, A. J., Farris, M., Alefounder, P., Williams, P. H., Woodward, M. J., and O'Connor, C. D. Molecular Microbiology 48, 507-521 (2003).
  4. Owens, R. M., Pritchard, G., Skipp, P., Hodey, M., Connell, S. R., Nierhaus, K. H., and O'Connor, C. D. EMBO Journal 23, 3375-3385 (2004).
  5. Agrawal, R. K., Heagle, A. B., Penczek, P., Grassucci, R. A., and Frank, J. Nature Structural Biology 6, 643-647 (1999).

Raymond S. Brown
Megan A. deLivron
Victoria L. Robinson*

Department of Molecular and Cell Biology
University of Connecticut
Storrs, CT 06269

*Phone: (860)-486-4353
Fax: (860)-486-4353
Email: victoria.robinson@uconn.edu