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

Given the observed differences in S. aureus binding between diverse primate hemoglobins, we 205 considered how genetic variation in IsdB might impact this interaction. The IsdB NEAT1 subdomain 206 Q162R-S170T is critical for hemoglobin recognition and is completely conserved among more than three 207 thousand S. aureus clinical isolates (11). Therefore, IsdB variation among congeneric S. argenteus and 208 S. schweitzeri was assessed. These recently diverged taxa ( Figure 5A ) are both primate-associated and, 209 unlike most other staphylococci, encode IsdB. We measured the ability of IsdB from S. argenteus and S. 210 schweitzeri to bind hemoglobin by expressing them ectopically in S. aureus. Consistent with their overall 211 high sequence identity, S. schweitzeri and S. argenteus IsdB bind primate hemoglobin with a similar 212 pattern of species preference as S. aureus ( Figure 5B ). However, both the IsdB of S. schweitzeri and S. 213 argenteus display reduced binding of talapoin hemoglobin, and S. argenteus IsdB does not bind 214 marmoset significantly worse than human. These data indicate that variation among IsdB impacts 215 species-specific hemoglobin capture. 216 All rights reserved. No reuse allowed without permission.