Specific induction of fibronectin binding activity by hemoglobin in Candida albicans grown in defined media

Sizhuang Yan, Eric Nègre, Jo Anne Cashel, Nenghua Guo, Caron A. Lyman, Thomas J. Walsh, David D. Roberts

Research output: Contribution to journalArticlepeer-review

Abstract

Fibronectin (FN) is a major component of host extracellular matrix that may play an important role in the initiation and dissemination of Candida albicans infections. Expression of FN binding requires growth of C. albicans blastoconidia in complex medium, and the regulation of FN receptor expression is poorly understood. We now demonstrate that hemoglobin is a potent and specific inducer of FN receptor expression and describe a defined medium supplemented with hemoglobin that greatly and stably enhances the binding activity of C. albicans for soluble FN. Enhancement of FN binding by hemoglobin in strain 44807 was concentration dependent and was maximal at 0.1% hemoglobin with 20- to 80-fold enhancement. The hemoglobin-induced FN binding to C. albicans was saturable, with a K(d) of 2.7 x 10-8 M. Enhancement required growth of C. albicans in hemoglobin-containing medium, since simply exposing blastoconidia to hemoglobin in a nongrowing status did not enhance binding. Induction was reversible following removal of hemoglobin from the growth medium and not associated with germination. Inorganic or protein-bound iron was not sufficient for the induction, since other iron-containing proteins or inorganic iron salts were inactive. Growth in the simple medium yeast nitrogen base supplemented with hemoglobin increased cell adhesion to immobilized FN and to cultured monolayers of bovine corneal endothelial cells. These data suggest that hemoglobin may be an important regulator of FN binding activity in C. albicans and thus may play a role in its pathogenesis.

Original languageEnglish (US)
Pages (from-to)2930-2935
Number of pages6
JournalInfection and immunity
Volume64
Issue number8
DOIs
StatePublished - 1996

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases

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