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A point mutation in cpsE renders Streptococcus pneumoniae nonencapsulated and enhances its growth, adherence and competence.

Schaffner, TO; Hinds, J; Gould, KA; Wüthrich, D; Bruggmann, R; Küffer, M; Mühlemann, K; Hilty, M; Hathaway, LJ (2014) A point mutation in cpsE renders Streptococcus pneumoniae nonencapsulated and enhances its growth, adherence and competence. BMC Microbiology, 14 (210). ISSN 1471-2180 https://doi.org/10.1186/s12866-014-0210-x
SGUL Authors: Gould, Katherine Ann Hinds, Jason

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Abstract

BACKGROUND: The polysaccharide capsule is a major virulence factor of the important human pathogen Streptococcus pneumoniae. However, S. pneumoniae strains lacking capsule do occur. RESULTS: Here, we report a nasopharyngeal isolate of Streptococcus pneumoniae composed of a mixture of two phenotypes; one encapsulated (serotype 18C) and the other nonencapsulated, determined by serotyping, electron microscopy and fluorescence isothiocyanate dextran exclusion assay.By whole genome sequencing, we demonstrated that the phenotypes differ by a single nucleotide base pair in capsular gene cpsE (C to G change at gene position 1135) predicted to result in amino acid change from arginine to glycine at position 379, located in the cytoplasmic, enzymatically active, region of this transmembrane protein. This SNP is responsible for loss of capsule production as the phenotype is transferred with the capsule operon. The nonencapsulated variant is superior in growth in vitro and is also 117-fold more adherent to and more invasive into Detroit 562 human epithelial cells than the encapsulated variant.Expression of six competence pathway genes and one competence-associated gene was 11 to 34-fold higher in the nonencapsulated variant than the encapsulated and transformation frequency was 3.7-fold greater. CONCLUSIONS: We identified a new single point mutation in capsule gene cpsE of a clinical S. pneumoniae serotype 18C isolate sufficient to cause loss of capsule expression resulting in the co-existence of the encapsulated and nonencapsulated phenotype. The mutation caused phenotypic changes in growth, adherence to epithelial cells and transformability. Mutation in capsule gene cpsE may be a way for S. pneumoniae to lose its capsule and increase its colonization potential.

Item Type: Article
Additional Information: © 2014 Schaffner et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Keywords: Streptococcus pneumoniae, cpsE, Capsule, Nonencapsulated, SNP, Science & Technology, Life Sciences & Biomedicine, Microbiology, PHASE VARIATION, CAPSULAR POLYSACCHARIDE BIOSYNTHESIS, SEROLOGICAL CHARACTERIZATION, MOLECULAR CHARACTERIZATION, PNEUMOCOCCAL-SEROTYPE, GENETIC-TRANSFORMATION, SUPPRESSOR MUTATIONS, ENCAPSULATED STRAINS, COLONIAL MORPHOLOGY, EPITHELIAL-CELLS, 11 Medical And Health Sciences, 06 Biological Sciences, 07 Agricultural And Veterinary Sciences
SGUL Research Institute / Research Centre: Academic Structure > Infection and Immunity Research Institute (INII)
Journal or Publication Title: BMC Microbiology
ISSN: 1471-2180
Language: eng
Dates:
DateEvent
28 August 2014Published
PubMed ID: 25163487
Web of Science ID: WOS:000341210800001
Go to PubMed abstract
URI: https://openaccess.sgul.ac.uk/id/eprint/107239
Publisher's version: https://doi.org/10.1186/s12866-014-0210-x

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