University of Leicester
Browse
journal.ppat.1006263.pdf (1.77 MB)

Deacetylation of sialic acid by esterases potentiates pneumococcal neuraminidase activity for mucin utilization, colonization and virulence.

Download (1.77 MB)
journal contribution
posted on 2017-03-30, 15:17 authored by Hasan F. Kahya, Peter W. Andrew, Hasan Yesilkaya
Pneumococcal neuraminidase is a key enzyme for sequential deglycosylation of host glycans, and plays an important role in host survival, colonization, and pathogenesis of infections caused by Streptococcus pneumoniae. One of the factors that can affect the activity of neuraminidase is the amount and position of acetylation present in its substrate sialic acid. We hypothesised that pneumococcal esterases potentiate neuraminidase activity by removing acetylation from sialic acid, and that will have a major effect on pneumococcal survival on mucin, colonization, and virulence. These hypotheses were tested using isogenic mutants and recombinant esterases in microbiological, biochemical and in vivo assays. We found that pneumococcal esterase activity is encoded by at least four genes, SPD_0534 (EstA) was found to be responsible for the main esterase activity, and the pneumococcal esterases are specific for short acyl chains. Assay of esterase activity by using natural substrates showed that both the Axe and EstA esterases could use acetylated xylan and Bovine Sub-maxillary Mucin (BSM), a highly acetylated substrate, but only EstA was active against tributyrin (triglyceride). Incubation of BSM with either Axe or EstA led to the acetate release in a time and concentration dependent manner, and pre-treatment of BSM with either enzyme increased sialic acid release on subsequent exposure to neuraminidase A. qRT-PCR results showed that the expression level of estA and axe increased when exposed to BSM and in respiratory tissues. Mutation of estA alone or in combination with nanA (codes for neuraminidase A), or the replacement of its putative serine active site to alanine, reduced the pneumococcal ability to utilise BSM as a sole carbon source, sialic acid release, colonization, and virulence in a mouse model of pneumococcal pneumonia.

Funding

HFK has received studentship from the Government of Iraq for this work.

History

Citation

PLoS Pathogens, 2017, 13 (3), e1006263.

Author affiliation

/Organisation/COLLEGE OF MEDICINE, BIOLOGICAL SCIENCES AND PSYCHOLOGY/School of Medicine/Department of Infection, Immunity and Inflammation

Version

  • VoR (Version of Record)

Published in

PLoS Pathogens

Publisher

Public Library of Science

issn

1553-7366

eissn

1553-7374

Acceptance date

2017-02-27

Copyright date

2017

Available date

2017-03-30

Publisher version

http://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1006263

Language

en

Usage metrics

    University of Leicester Publications

    Categories

    No categories selected

    Keywords

    Licence

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC