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The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. . https://doi.org/10.1101/339705 doi: bioRxiv preprint purified, providing broad representation from our phylogenetic dataset. An established biochemical assay 125 was used to measure binding of hemoglobin by S. aureus, in which S. aureus cells recognize recombinant 126 human hemoglobin as well as hemoglobin purified from blood in an IsdB-dependent manner 127 (Supplemental Figure 1 ). S. aureus exhibited significantly reduced binding of baboon and marmoset 128 hemoglobin to the cell surface ( Figure 2A) . It was noted that binding patterns do not strictly match 129 predictions based on host phylogeny, suggesting discrete large-effect substitutions in hemoglobin may 130 contribute disproportionately to recognition by S. aureus. We next determined the ability of primate 131 hemoglobins to support growth of S. aureus as the sole iron source. Consistent with whole-cell binding 132 data, hemoglobins that were bound by S. aureus with low affinity were unable to support optimal bacterial 133 growth, indicating that the capability to bind hemoglobin is a measure of the ability to utilize hemoglobin 134 as an iron source ( Figure 2B ).