Interaction of α-agglutinin and a-agglutinin, Saccharomyces cerevisiae sexual cell adhesion molecules

H. Zhao, Z. M. Shen, P. C. Kahn, P. N. Lipke

Research output: Contribution to journalArticle

34 Scopus citations

Abstract

α-Agglutinin and a-agglutinin are complementary cell adhesion glycoproteins active during mating in the yeast Saccharomyces cerevisiae. They bind with high affinity and high specificity: cells of opposite mating types are irreversibly bound by a few pairs of agglutinins. Equilibrium and surface plasmon resonance kinetic analyses showed that the purified binding region of α-agglutinin interacted similarly with purified a-agglutinin and with a-agglutinin expressed on cell surfaces. At 20°C, the KD for the interaction was 2 × 10-9 to 5 × 10-9 M. This high affinity was a result of a very low dissociation rate (≈ 2.6 × 10-4 s-1) coupled with a low association rate (= 5 × 104 M-1 s-1). Circular-dichroism spectroscopy showed that binding of the proteins was accompanied by measurable changes in secondary structure. Furthermore, when binding was assessed at 10°C, the association kinetics were sigmoidal, with a very low initial rate. An induced-fit model of binding with substantial apposition of hydrophobic surfaces on the two ligands can explain the observed affinity, kinetics, and specificity and the conformational effects of the binding reaction.

Original languageEnglish (US)
Pages (from-to)2874-2880
Number of pages7
JournalJournal of bacteriology
Volume183
Issue number9
DOIs
StatePublished - 2001

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Microbiology

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