Kenyon Johanna J, Duda Katarzyna A, De Felice Antonia, Cunneen Monica M, Molinaro Antonio, Laitinen Juha, Skurnik Mikael, Holst Otto, Reeves Peter R, De Castro Cristina
School of Molecular Bioscience, University of Sydney, Sydney, NSW, Australia.
Division of Structural Biochemistry, Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Borstel, Germany.
Innate Immun. 2016 Apr;22(3):205-17. doi: 10.1177/1753425916631403. Epub 2016 Feb 11.
In Yersinia pseudotuberculosis complex, the O-antigen of LPS is used for the serological characterization of strains, and 21 serotypes have been identified to date. The O-antigen biosynthesis gene cluster and corresponding O-antigen structure have been described for 18, leaving O:8, O:13 and O:14 unresolved. In this study, two O:8 isolates were examined. The O-antigen gene cluster sequence of strain 151 was near identical to serotype O:4a, though a frame-shift mutation was found in ddhD, while No. 6 was different to 151 and carried the O:1b gene cluster. Structural analysis revealed that No. 6 produced a deeply truncated LPS, suggesting a mutation within the waaF gene. Both ddhD and waaF were cloned and expressed in 151 and No. 6 strains, respectively, and it appeared that expression of ddhD gene in strain 151 restored the O-antigen on LPS, while waaF in No. 6 resulted in an LPS truncated less severely but still without the O-antigen, suggesting that other mutations occurred in this strain. Thus, both O:8 isolates were found to be spontaneous O-antigen-negative mutants derived from other validated serotypes, and we propose to remove this serotype from the O-serotyping scheme, as the O:8 serological specificity is not based on the O-antigen.
在假结核耶尔森菌复合体中，脂多糖（LPS）的O抗原用于菌株的血清学鉴定，迄今为止已鉴定出21种血清型。已描述了18种血清型的O抗原生物合成基因簇及相应的O抗原结构，O:8、O:13和O:14血清型仍未明确。在本研究中，检测了两株O:8分离株。菌株151的O抗原基因簇序列与O:4a血清型几乎相同，不过在ddhD基因中发现了一个移码突变，而6号菌株与151不同，携带O:1b基因簇。结构分析显示，6号菌株产生了深度截短的LPS，提示waaF基因存在突变。分别在151和6号菌株中克隆并表达了ddhD和waaF基因，结果显示，151菌株中ddhD基因的表达恢复了LPS上的O抗原，而6号菌株中waaF基因的表达导致LPS截短程度较轻，但仍无O抗原，提示该菌株还发生了其他突变。因此，发现两株O:8分离株均为源自其他已确认血清型的自发O抗原阴性突变体，鉴于O:8血清学特异性并非基于O抗原，我们建议从O血清分型方案中去除该血清型。
