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Taxonomic group: bacteria / Proteobacteria (Phylum: Proteobacteria)
Host organism: Homo sapiens
Associated disease: bacillary dysentery (shigellosis) [ICD11: 1A02

, ICD11: SA56

, ICD11: XN7HG

]; infection due to Shigella flexneri [ICD11: XN7Y2

]

The structure was elucidated in this paper
NCBI PubMed ID: 25112477
Publication DOI: 10.1128/JB.02009-14
Journal NLM ID: 2985120R
Publisher: American Society for Microbiology
Correspondence: Qiangzheng Sun <sunqiangzheng

icdc.cn>; Jianguo Xu <xujianguo

icdc.cn>
Institutions: N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, China CDC, Changping, Beijing, China, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia

Shigella flexneri O-antigen is an important and highly variable cell component presented on the outer leaflet of the outer membrane. Most Shigella flexneri bacteria share an O-antigen backbone composed of →2)-α-L-Rhap(III)-(1→2)-α-L-Rhap(II)-(1→3)-α-L-Rhap(I)-(1→3)-β-D-GlcpNAc-(1→ repeats, which can be modified by adding various chemical groups to different sugars, giving rise to diverse O-antigen structures and, correspondingly, to various serotypes. The known modifications include glucosylation on various sugar residues, O-acetylation on Rha(I) or/and Rha(III), and phosphorylation with phosphoethanolamine on Rha(II) or/and Rha(III). Recently, a new O-antigen modification, namely, O-acetylation at position 6 of N-acetylglucosamine (GlcNAc), has been identified in S. flexneri serotypes 2a, 3a, Y, and Yv. In this study, the genetic basis of the 6-O-acetylation of GlcNAc in S. flexneri was elucidated. An O-acyltransferase gene designated oacD was found to be responsible for this modification. The oacD gene is carried on serotype-converting bacteriophage SfII, which is integrated into the host chromosome by lysogeny to form a prophage responsible for the evolvement of serotype 2 of S. flexneri. The OacD-mediated 6-O-acetylation also occurs in some other S. flexneri serotypes that carry a cryptic SfII prophage with a dysfunctional gtr locus for type II glucosylation. The 6-O-acetylation on GlcNAc confers to the host a novel O-antigen epitope, provisionally named O-factor 10. These findings enhance our understanding of the mechanisms of the O-antigen variation and enable further studies to understand the contribution of the O-acetylation to the antigenicity and pathogenicity of S. flexneri.

structure, O-antigen, Shigella flexneri, epitope, Serotypes, bacteriophage, acyltransferase

Structure type: polymer chemical repeating unit
Location inside paper: p.3661, table 5, Sf301 (2a), Sf301∆oacD_pSQZ6
Compound class: O-polysaccharide, O-antigen
Contained glycoepitopes: IEDB_125613,IEDB_125614,IEDB_127514,IEDB_130687,IEDB_133752,IEDB_133753,IEDB_133754,IEDB_135806,IEDB_135807,IEDB_135808,IEDB_135809,IEDB_135813,IEDB_135817,IEDB_135849,IEDB_136105,IEDB_137340,IEDB_141807,IEDB_141815,IEDB_141816,IEDB_142488,IEDB_143253,IEDB_144998,IEDB_146664,IEDB_151531,IEDB_153213,IEDB_225177,IEDB_885823,IEDB_983931,SB_192

Methods: 13C NMR, 1H NMR, NMR-2D, DNA techniques, 31P NMR, Western blotting, de-O-acetylation, serological methods, genetic methods, bioinformatic analysis, serotyping analysis
Biosynthesis and genetic data: Identification of an oac homolog (designated oacD) and demonstration of this gene to be responsible for 6-O-acetylation at GlcNAc in S. flexneri O-antigens
Comments, role: NMR data of OPS from S.flexneri Sf301∆oacD_pSQZ6 mutant strain with aLRhap3Ac residue in chain. NMR data for aLRhap4Ac: 1H ? ? ? 4.79 ? ?, 13C ? ? ? 75.4 ? ?.

Related record ID(s): 30140, 30482, 30483, 30484, 30485, 30486
NCBI Taxonomy refs (TaxIDs): 198214
Show glycosyltransferases

NMR conditions: in D2O at 313 K [as TSV]

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
3,3,2	aLRhap	?	?	73.9	?	?	?
3,3	aLRhap
3,4	aDGlcp
3	aLRhap
2	Ac
6	65%Ac	?	21.5
	bDGlcpN	?	?	?	?	?	64.5
3,3,2,3	45%Ac	?	21.8
3,3,2,4	25%Ac	?	21.7


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
3,3,2	aLRhap	?	?	5.08	?	?	?
3,3	aLRhap
3,4	aDGlcp
3	aLRhap
2	Ac
6	65%Ac	-	2.14
	bDGlcpN	?	?	?	?	?	4.32-4.41
3,3,2,3	45%Ac	-	2.21
3,3,2,4	25%Ac	-	2.16


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
3,3,2	aLRhap	?/?	?/?	73.9/5.08	?/?	?/?	?/?
3,3	aLRhap
3,4	aDGlcp
3	aLRhap
2	Ac
6	65%Ac		21.5/2.14
	bDGlcpN	?/?	?/?	?/?	?/?	?/?	64.5/4.32-4.41
3,3,2,3	45%Ac		21.8/2.21
3,3,2,4	25%Ac		21.7/2.16

¹H NMR data:

Linkage	Residue	H1	H2	H3	H4	H5	H6
3,3,2	aLRhap	?	?	5.08	?	?	?
3,3	aLRhap
3,4	aDGlcp
3	aLRhap
2	Ac
6	65%Ac		2.14
	bDGlcpN	?	?	?	?	?	4.32 4.41
3,3,2,3	45%Ac		2.21
3,3,2,4	25%Ac		2.16

¹³C NMR data:

Linkage	Residue	C1	C2	C3	C4	C5	C6
3,3,2	aLRhap	?	?	73.9	?	?	?
3,3	aLRhap
3,4	aDGlcp
3	aLRhap
2	Ac
6	65%Ac	?	21.5
	bDGlcpN	?	?	?	?	?	64.5
3,3,2,3	45%Ac	?	21.8
3,3,2,4	25%Ac	?	21.7

The spectrum also has 13 signals at unknown positions (not plotted).

There is only one chemically distinct structure:

*O[C@H]1[C@H](O[C@H]2[C@H](O[C@@H]3[C@@H](O[C@H]4O[C@H](CO)[C@@H](O)[C@H](O)[C@H]4O)[C@H](C)O[C@@H](O[C@@H]4[C@@H](NC(C)=O)[C@H](*)O[C@H](COC(C)=O)[C@H]4O)[C@@H]3O)O[C@@H](C)[C@H](O)[C@H]2O)O[C@@H](C)[C@H](O)[C@H]1O

SVG MW SMILES 3D mol Ionize