Open AccessCapsule loss or death: The position of mutations among capsule genes sways the destiny of S treptococcus suis
Author(s) -
Lakkitjaroen Nattakan,
Takamatsu Daisuke,
Okura Masatoshi,
Sato Masumi,
Osaki Makoto,
Sekizaki Tsutomu
Publication year - 2014
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/1574-6968.12428
Subject(s) - streptococcus suis , biology , gene , microbiology and biotechnology , virulence , frameshift mutation , virulence factor , genetics , mutation , pathogen , bacterial capsule
S treptococcus suis , an emerging zoonotic pathogen, is responsible for various diseases in swine and humans. Most S . suis strains from clinical cases possess a group of capsular polysaccharide synthesis ( cps ) genes and phenotypically express capsular polysaccharides ( CP s). Although CP s are considered to be an important virulence factor, our previous study showed that many S . suis isolates from porcine endocarditis lost their CP s, and some of these unencapsulated isolates had large insertions or deletions in the cps gene clusters. We further investigated 25 endocarditis isolates with no obvious genetic alterations to elucidate the unencapsulation mechanisms and found that a single‐nucleotide substitution and frameshift mutation in two glycosyltransferase genes ( cps2E and cps2F ) were the main causes of the capsule loss. Moreover, mutations in the genes involved in side‐chain formation ( cps2J and cps2N ), polymerase ( cps2I ), and flippase ( cps2O ) appeared to be lethal; however, these lethal effects were relieved by mutations in the cps2 EF region. As unencapsulation and even the death of individual cells have recently been suggested to be beneficial to the pathogenesis of infections, the results of the present study provide a further insight into understanding the biological significance of cps mutations during the course of S . suis infections.