exploring the biophysical origins of molecular evolution

  • Methicillin resistant Staphylococcus aureus (MRSA) kills more Americans per year than HIV/AIDS, emphysema, Parkinson’s diseases and homicides COMBINED. (Infectious Disease Society of America)
  • Nearly 2 million Americans per year will develop hospital acquired infections (HAIs) (99,000 deaths)
  • Sepsis and pneumonia alone kills ~50,000 American per year and costs 21-34 billion dollars mostly due to MDR pathogens

Our interest in molecular evolution is stimulated by the rise in drug resistant pathogens and how understanding the physical basis for adaptation can be used for prediction of resistance and the identification of new targets and strategies for antimicrobial therapies. By combining approaches from biophysics and experimental evolution we are able to identify and characterize intermediates along the mutational pathways of adaptation and then link those intermediates to the overall evolutionary trajectory of the bacterial populations. Adaptive changes in protein sequence and expression impact organismal fitness and, consequently, dictate population dynamics. By combining experimental evolution with molecular biophysics we take a systems level view of adaptation and link it to the molecular mechanism responsible for the resulting evolutionary dynamics.


—Yousif Shamoo




Hammerstrom,T.G., Beabout, K., Clements, T.P., Saxer, G., Shamoo, Y., "Acinetobacter baumannii repeatedly evolves a hypermutator phenotype in response to tigecycline that effectively surveys evolutionary trajectories to resistance.PLOS one (in press)


Press release:

Researchers strategize to outsmart bacteria.


Beabout, K., Hammerstrom, T.G., Perez A., Magalhães, B., Prater, A., Clements, T.P., Arias, C., Saxer, G., Shamoo, Y. "The ribosomal S10 protein is a general target for decreased tigecycline susceptibility." Antimicrobial Agents and Chemotherapy (2015)


Beabout, K., Hammerstrom, T.G., Wang, T.T., Bhatty, M., Christie, P.J., Saxer, G., Shamoo, Y. "Rampant parasexuality evolves in a hospital pathogen during antibiotic selection." Molecular Biology and Evolution (2015)

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