L Liu1,2, Y Li3,4, X Wang5,6,7, W Guo2. 1. State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China. 2. School of Biotechnology, Jiangnan University, Wuxi, China. 3. State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China. yanyanli1123@hotmail.com. 4. Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, China. yanyanli1123@hotmail.com. 5. State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China. xwang@jiangnan.edu.cn. 6. School of Biotechnology, Jiangnan University, Wuxi, China. xwang@jiangnan.edu.cn. 7. Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, China. xwang@jiangnan.edu.cn.
Abstract
AIMS: Investigate how Cronobacter sakazakii modify their lipid A structure to avoid recognition by the host immune cells. METHODS AND RESULTS: Lipid A modification was observed in C. sakazakii BAA894 grown at pH 5·0 but not pH 7·0. Overexpression of C. sakazakii gene ESA_RS09200 in Escherichia coli W3110 caused a phosphoethanolamine (PEA) modification of lipid A; when ESA_RS09200 was deleted in C. sakazakii BAA894, this lipid A modification disappeared. Lipid A modification was observed in BAA894 grown at pH 5·0 when the 1- phosphate residue of lipid A was removed, but disappeared when the 4'- phosphate residue of lipid A was removed. When ESA_RS16430, the orthologous gene of E. coli pmrA, was deleted in C. sakazakii BAA894, this PEA modification of lipid A was still observed, suggesting that this modification was not regulated by the PmrA-PmrB system. Compared to the wild-type BAA894, ESA_RS09200 deletion mutant showed decreased resistance to cationic antimicrobial peptides (CAMP), increased recognition by TLR4/MD2, decreased ability to invade and persist in mammalian cells. CONCLUSIONS: ESA_RS09200 in C. sakazakii BAA894 encodes a PEA transferase that specifically adds a PEA to the 4'-phosphate residue of lipid A, but not regulated by the PmrA-PmrB system. PEA modification of lipid A reduces recognition and killing by the host innate immune system. SIGNIFICANCE AND IMPACT OF THE STUDY: This study showed that modification of the lipid A moiety of C. sakazakii with PEA increased resistance to CAMP and recognition of the immune response although signalling of TLR4/MD2 cascade, suggesting that the organism could not successfully evade the host innate immune system without the transference of PEA to its lipid A moiety.
AIMS: Investigate how Cronobacter sakazakii modify their lipid A structure to avoid recognition by the host immune cells. METHODS AND RESULTS:Lipid A modification was observed in C. sakazakii BAA894 grown at pH 5·0 but not pH 7·0. Overexpression of C. sakazakii gene ESA_RS09200 in Escherichia coli W3110 caused a phosphoethanolamine (PEA) modification of lipid A; when ESA_RS09200 was deleted in C. sakazakii BAA894, this lipid A modification disappeared. Lipid A modification was observed in BAA894 grown at pH 5·0 when the 1- phosphate residue of lipid A was removed, but disappeared when the 4'- phosphate residue of lipid A was removed. When ESA_RS16430, the orthologous gene of E. coli pmrA, was deleted in C. sakazakii BAA894, this PEA modification of lipid A was still observed, suggesting that this modification was not regulated by the PmrA-PmrB system. Compared to the wild-type BAA894, ESA_RS09200 deletion mutant showed decreased resistance to cationic antimicrobial peptides (CAMP), increased recognition by TLR4/MD2, decreased ability to invade and persist in mammalian cells. CONCLUSIONS: ESA_RS09200 in C. sakazakii BAA894 encodes a PEA transferase that specifically adds a PEA to the 4'-phosphate residue of lipid A, but not regulated by the PmrA-PmrB system. PEA modification of lipid A reduces recognition and killing by the host innate immune system. SIGNIFICANCE AND IMPACT OF THE STUDY: This study showed that modification of the lipid A moiety of C. sakazakii with PEA increased resistance to CAMP and recognition of the immune response although signalling of TLR4/MD2 cascade, suggesting that the organism could not successfully evade the host innate immune system without the transference of PEA to its lipid A moiety.
Authors: Marta Kaszowska; Marta Wojcik; Jakub Siednienko; Czeslaw Lugowski; Jolanta Lukasiewicz Journal: Front Immunol Date: 2017-12-11 Impact factor: 7.561