Self-aggregation of Cryptococcus neoformans capsular glucuronoxylomannan is dependent on divalent cations

Leonardo Nimrichter, Susana Frases, Leonardo P. Cinelli, Nathan B. Viana, Antonio Nakouzi, Luiz R. Travassos, Arturo Casadevall, Marcio L. Rodrigues

Research output: Contribution to journalArticle

Abstract

The capsular components of the human pathogen Cryptococcus neoformans are transported to the extracellular space and then used for capsule enlargement by distal growth. It is not clear, however, how the glucuronoxylomannan (GXM) fibers are incorporated into the capsule. In the present study, we show that concentration of C. neoformans culture supernatants by ultrafiltration results in the formation of highly viscous films containing pure polysaccharide, providing a novel, nondenaturing, and extremely rapid method to isolate extracellular GXM. The weight-averaged molecular mass of GXM in the film, determined using multiangle laser light scattering, was ninefold smaller than that of GXM purified from culture supernatants by differential precipitation with cetyl trimethyl ammonium bromide (CTAB). Polysaccharides obtained either by ultrafiltration or by CTAB-mediated precipitation showed different reactivities with GXM-specific monoclonal antibodies. Viscosity analysis associated with inductively coupled plasma mass spectrometry and measurements of zeta potential in the presence of different ions implied that polysaccharide aggregation was a consequence of the interaction between the carboxyl groups of glucuronic acid and divalent cations. Consistent with this observation, capsule enlargement in living C. neoformans cells was influenced by Ca2+ in the culture medium. These results suggest that capsular assembly in C. neoformans results from divalent cation-mediated self-aggregation of extracellularly accumulated GXM molecules.

Original languageEnglish (US)
Pages (from-to)1400-1410
Number of pages11
JournalEukaryotic Cell
Volume6
Issue number8
DOIs
StatePublished - Aug 1 2007
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

Fingerprint Dive into the research topics of 'Self-aggregation of Cryptococcus neoformans capsular glucuronoxylomannan is dependent on divalent cations'. Together they form a unique fingerprint.

  • Cite this

    Nimrichter, L., Frases, S., Cinelli, L. P., Viana, N. B., Nakouzi, A., Travassos, L. R., Casadevall, A., & Rodrigues, M. L. (2007). Self-aggregation of Cryptococcus neoformans capsular glucuronoxylomannan is dependent on divalent cations. Eukaryotic Cell, 6(8), 1400-1410. https://doi.org/10.1128/EC.00122-07