Poster Presentation The 42nd Lorne Conference on Protein Structure and Function 2017

Structural and functional characterization of PsaBCA, the manganese transporter in Streptococcus pneumoniae. (#291)

Jennie Sjöhamn 1 , Christopher McDevitt 2 , Norimichi Nomura 3 4 , So Iwata 3 4 5 , Megan J Maher 1
  1. La Trobe University, Melbourne, VIC, Australia
  2. Research Center for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
  3. Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
  4. Research Acceleration Program, Membrane Protein Crystallography Project, Japan Science and Technology Agency, Kyoto, Japan
  5. RIKEN SPring-8 Center, SPring-8, Hyogo, Japan

Streptococcus pneumoniae is the world’s foremost bacterial pathogen, being responsible for more than one million deaths worldwide annually. S. pneumoniae has an absolute requirement for the trace element manganese (Mn), in order to survive in the host environment. Manganese is specifically acquired by the ABC transporter PsaBCA, which includes three subunits: a nucleotide binding domain (PsaB), a transmembrane domain (PsaC) and a substrate binding domain (PsaA).

We have successfully overexpressed the PsaBC complex, and crystallisation trials have resulted in the identification of a number of crystallisation conditions that yield crystals with different morphologies. In parallel, novel techniques such as lipidic cubic phase crystallization and co-crystallization with Fab antibody fragments are being employed.

In addition, we are interested in characterising the binding affinity of the substrate-binding domain, PsaA, to the PsaBC complex. PsaA is able to bind a variety of transition metal cations, including its specific substrate manganese, however only manganese binding promotes functional metal transport (1,2). We aim to elucidate the basis for this specificity by determining the affinity of interactions between PsaA and PsaBC in the presence of different metal substrates.

This poster will describe our recent progress toward the structural and functional characterisation of PsaBCA, which will allow us to understand the mechanism of manganese transport and its specificity in S. pneumonia. The work presented here has implications for the potential treatment of Streptococcus pneumoniae infections.

  1. McAllister, L. J., Tseng, H. J., Ogunniyi, A. D., Jennings, M. P., McEwan, A. G., & Paton, J. C. (2004). Molecular analysis of the psa permease complex of Streptococcus pneumoniae. Molecular Microbiology, 53(3), 889–901.
  2. McDevitt, C. A., Ogunniyi, A. D., Valkov, E., Lawrence, M. C., Kobe, B., McEwan, A. G., & Paton, J. C. (2011). A Molecular Mechanism for Bacterial Susceptibility to Zinc. PLoS Pathogens, 7(11), e1002357.