The effects of differences in pspA alleles and capsular types on the resistance of Streptococcus pneumoniae to killing by apolactoferrin.

Academic Article

Abstract

  • Pneumococcal surface protein A (PspA) is the only pneumococcal surface protein known to strongly bind lactoferrin on the bacterial surface. In the absence of PspA Streptococcus pneumoniae becomes more susceptible to killing by human apolactoferrin (apo-hLf), the iron-free form of lactoferrin. In the present study we examined diverse strains of S.¬†pneumoniae that differed by 2 logs in their susceptibility to apo-hLf. Among these strains, the amount of apo-hLf that bound to cell surface PspA correlated directly with the resistance of the strain to killing by apo-hLf. Moreover examination of different pspA alleles on shared genetic backgrounds revealed that those PspAs that bound more lactoferrin conferred greater resistance to killing by apo-hLf. The effects of capsule on killing of pneumococci by apo-hLf were generally small, but on one genetic background, however, the lack of capsule was associated with 4-times as much apo-hLf binding and 30-times more resistance to killing by apo-hLf. Overall these finding strongly support the hypothesis that most of the variation in the ability of apo-hLf is dependent on the variation in the binding of apo-hLf to surface PspA and this binding is dependent on variation in PspA as well as variation in capsule which may enhance killing by reducing the binding of apo-hLf to PspA.
  • Published In

    Keywords

  • Alleles, Anti-Bacterial Agents, Apoproteins, Bacterial Capsules, Bacterial Proteins, Genetic Variation, Humans, Lactoferrin, Microbial Viability, Protein Binding, Streptococcus pneumoniae
  • Digital Object Identifier (doi)

    Author List

  • Mirza S; Benjamin WH; Coan PA; Hwang S-A; Winslett A-K; Yother J; Hollingshead SK; Fujihashi K; Briles DE
  • Start Page

  • 209
  • End Page

  • 219
  • Volume

  • 99