Book of Abstracts: Albany 2007
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
Raymond S. Brown
Department of Molecular and Cell Biology