Molecular basis for the evolution of species-specific hemoglobin capture by pathogenic Staphylococcus

Jacob E. Choby; Hanna B. Buechi; Allison J. Farrand; Eric P. Skaar; Matthew F. Barber

The identification of rapidly evolving sites at the IsdB binding interface in both α-globin and β-149 globin suggest that natural selection in primate globins has been driven by antagonistic evolutionary 150 conflicts with related families of bacterial receptors during primate divergence. Mechanistically, these 151 findings also suggest that both globins contribute to S. aureus species-specific hemoglobin capture. We 152 therefore exploited the enhanced binding of human hemoglobin relative to baboon to examine the role of 153 each globin subunit in this biochemical interaction. The ability of S. aureus to bind chimeric hemoglobins 154 was measured, which revealed that both globins contribute to species-specificity ( Figure 3A ), as chimeras 155 containing either human α-or β-globin were bound more effectively than baboon hemoglobin. However, 156