TY - JOUR
T1 - Capsule of Cryptococcus neoformans grows by enlargement of polysaccharide molecules
AU - Frases, Susana
AU - Pontes, Bruno
AU - Nimrichter, Leonardo
AU - Viana, Nathan B.
AU - Rodrigues, Marcio L.
AU - Casadevall, Arturo
PY - 2009/1/27
Y1 - 2009/1/27
N2 - The human pathogenic fungus Cryptococcus neoformans has a distinctive polysaccharide (PS) capsule that enlarges during infection. The capsule is essential for virulence, but the mechanism for capsular growth is unknown. In the present study, we used dynamic light scattering (LS) analysis of capsular PS and optical tweezers (OT) to explore the architecture of the capsule. Analysis of capsular PS from cells with small and large capsules by dynamic LS revealed a linear correlation between PS effective diameter and microscopic capsular diameter. This result implied that capsule growth was achieved by the addition of molecules with larger effective diameter, such that some molecules can span the entire diameter of the capsule. Measurement of polystyrene bead penetration of C. neoformans capsules by using OT techniques revealed that the outer regions were penetrable, but not the inner regions. Our results provide a mechanism for capsular enlargement based on the axial lengthening of PS molecules and suggest a model for the architecture of a eukaryotic microbial capsule.
AB - The human pathogenic fungus Cryptococcus neoformans has a distinctive polysaccharide (PS) capsule that enlarges during infection. The capsule is essential for virulence, but the mechanism for capsular growth is unknown. In the present study, we used dynamic light scattering (LS) analysis of capsular PS and optical tweezers (OT) to explore the architecture of the capsule. Analysis of capsular PS from cells with small and large capsules by dynamic LS revealed a linear correlation between PS effective diameter and microscopic capsular diameter. This result implied that capsule growth was achieved by the addition of molecules with larger effective diameter, such that some molecules can span the entire diameter of the capsule. Measurement of polystyrene bead penetration of C. neoformans capsules by using OT techniques revealed that the outer regions were penetrable, but not the inner regions. Our results provide a mechanism for capsular enlargement based on the axial lengthening of PS molecules and suggest a model for the architecture of a eukaryotic microbial capsule.
KW - GXM
KW - GalXM
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U2 - 10.1073/pnas.0808995106
DO - 10.1073/pnas.0808995106
M3 - Article
C2 - 19164571
AN - SCOPUS:59049087993
SN - 0027-8424
VL - 106
SP - 1228
EP - 1233
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 4
ER -