Abstract

N-linked mannans (N-mannans) in the cell wall of Candida albicans are thought to mask β-(1,3)-glucan from recognition by Dectin-1, contributing to innate immune evasion. Lateral cell wall exposures of glucan on C. albicans are predominantly single receptor-ligand interaction sites and are restricted to nanoscale geometries. Candida species exhibit a range of basal glucan exposures and their mannans also vary in size and complexity at the molecular level. We used super resolution fluorescence imaging and a series of protein mannosylation mutants in C. albicans and C. glabrata to investigate the role of specific N-mannan features in regulating the nanoscale geometry of glucan exposure. Decreasing acid labile mannan abundance and α-(1,6)-mannan backbone length correlated most strongly with increased density and nanoscopic size of glucan exposures in C. albicans and C. glabrata, respectively. Additionally, a C. albicans clinical isolate with high glucan exposure produced similarly perturbed N-mannan structures and exhibited similar changes to nanoscopic glucan exposure geometry. We conclude that acid labile N-mannan controls glucan exposure geometry at the nanoscale. Furthermore, variations in glucan nanoexposure characteristics are clinically relevant and are likely to impact the nature of the pathogenic surface presented to innate immunocytes at dimensions relevant to receptor engagement, aggregation and signaling.

Highlights

  • 2646-Pos Board B662 Superresolution Microscopy of the T Cell Receptor in the Immunological Synapse Florian Baumgart1, Benedikt K

  • 2650-Pos Board B666 Quantitative Microscopy Pipeline for Building a Model of the Human Cell Winfried Wiegraebe, Allen Institute for Cell Science Team

  • We have previously found that characteristic blinking and resulting overcounting of fluorescent proteins and organic dyes may be misinterpreted as molecular clusters

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Summary

Introduction

2646-Pos Board B662 Superresolution Microscopy of the T Cell Receptor in the Immunological Synapse Florian Baumgart1, Benedikt K. Single molecule localization-based superresolution microscopy has been used to report the presence of protein nanoclusters at the T cell plasma membrane. We have previously found that characteristic blinking and resulting overcounting of fluorescent proteins and organic dyes may be misinterpreted as molecular clusters.

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