English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Background  O-antigen (O-polysaccharide) of the lipopolysaccharide is a highly variable cell component of the outer membrane in  Shigella flexneri . It defines the serospecificity and plays an important role in the pathogenesis of shigellosis. There are two distinct O-antigen forms for the 19 serotypes of  S. flexneri : one for serotypes 1–5, X, Y, 7 (and their subtypes), and the other for serotype 6. Although having different basal O-polysaccharide structures, the two forms share a common disaccharide fragment [→2)-α- l -Rha p  III -(1 → 2)-α- l -Rha p  II ]. In serotype 6 and some non-6 serotypes, Rha III  is O-acetylated at position either 3 or 4 (3/4-O-acetylation), conferring to the hosts a novel antigenic determinant named O-factor 9. An acyltransferase gene ( oacB ) responsible for this modification has been identified in serotypes 1a, 1b, 2a, 5a, and Y, but not in serotype 6.    Results  Using genetic, serological, and chemical approaches, another acyltransferase gene named  oacC  was demonstrated to be responsible for the 3/4-O-acetylation on Rha III  in the O-antigen of  S. flexneri  serotype 6. Inactivation of the  oacC  gene resulted in the loss of the 3/4-O-acetyltion, and the cloned  oacC  gene restored this modification upon transformation. In accordance with the similarity in the acceptor substrate structure and high sequence homology (72% identity) between  oacC  and  oacB ,  oacC  has the interchangeable function with the  oacB  gene in mediation of the 3/4-O-acetylation. The  oacC  gene is located in a prophage on the chromosome and presented in all 77 serotype 6 strains tested.    Conclusions  Identification and functional characterization of the O-acetyltransferase encoding gene,  oacC , shows that it is involved in O-antigen modification by 3/4-O-acetylation on Rha III  specific to serotype 6.    Electronic supplementary material  The online version of this article (doi:10.1186/s12866-014-0266-7) contains supplementary material, which is available to authorized users.

bmc microbiology

Genetic and structural identification of an O-acyltransferase gene (oacC) responsible for the 3/4-O-acetylation on rhamnose III in Shigella flexneri serotype 6