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Institut de Biologie StructuraleGrenoble / France

How a bacterium manages to go unnoticed and increase its virulence

The capsule is the dominant Streptococcus pneumoniae virulence factor, yet how variation in capsule thickness is regulated is poorly understood. Here, IBs researchers, in collaboration with researchers from UCL Medical School, St George’s University of London and Leceister University, describe an unexpected relationship between mutation of adcAII, which encodes a zinc uptake lipoprotein, and capsule thickness. Mutation of adcAII resulted in a striking hyperencapsulated phenotype, increased resistance to complement-mediated neutrophil killing, and increased S. pneumoniae virulence in mouse models of infection. These results provide further evidence for the importance of the SpnD39III (ST5556II) type I restriction-modification system for modulating capsule thickness and identified an unexpected linkage between capsule thickness and mutation of ΔadcAII, further investigation of which could further characterize mechanisms of capsule regulation.

Deletion of the zinc transporter lipoprotein AdcAII causes hyperencapsulation of Streptococcus pneumoniae associated with distinct alleles of the Type I restriction modification system. Claire Durmort, Giuseppe Ercoli, Elisa Ramos-Sevillano, Suneeta Chimalapati, Richard D. Haigh, Megan De Ste Croix, Katherine Gould, Jason Hinds, Yann Guerardel, Thierry Vernet, Marco Oggioni, and Jeremy S Brown. Mbio ; 11, 2 e00445-20