title: Identification of Two Genes Encoding for the Late Acyltransferases of Lipid A in Klebsiella pneumoniae.
abstract: Lipid A, the hydrophobic anchor of lipopolysaccharide, is an essential component in the outer membrane of most gram-negative bacteria. It is recognized by the TLR4/MD2 receptor of the innate immune system, which triggers an inflammatory response accompanied by massive overproduction of cytokines and leads to gram-negative septic shock. Human pathogen Klebsiella pneumoniae, which may synthesize two lipid A species, differs by the length of the secondary acyl chain. In this study, we identified two genes encoding the putative late acyltransferases of lipid A biosynthesis pathway in K. pneumoniae. Based on the sequence alignment, proteins YP_002239312.1 encoded by KPK3489 and YP_002239899.1 encoded by KPK4096 are homologous to E. coli LpxL, which were designated as LpxL1 and LpxL2, respectively. Functions of the two acyltransferases were confirmed by overexpressing the genes in E. coli, isolating lipid A and analyzing their structures using an ESI/MS. Like E. coli LpxL, K. pneumoniae LpxL1 transfers a C12:0 secondary acyl chain to the 2'-position of lipid A, while K. pneumoniae LpxL2 transfers a C14:0 secondary acyl chain to the 2'-position primary acyl chain of lipid A. These two acyltransferases might play important roles in the biosynthesis of lipid A and the innate immune system recognition in K. pneumoniae.
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China. yanyanli1123@hotmail.com.|Key Laboratory of Industrial Biotechnology of Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China. yanyanli1123@hotmail.com.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Key Laboratory of Industrial Biotechnology of Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Yun
authors.affiliation: Key Laboratory of Industrial Biotechnology of Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.|Key Laboratory of Industrial Biotechnology of Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Li
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.|Key Laboratory of Industrial Biotechnology of Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.
authors.forename: Xiaoyuan
authors.initials: X
authors.lastname: Wang
mesh_terms: D000217:Acyltransferases / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000378:metabolism; D007711:Klebsiella pneumoniae / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D008050:Lipid A / Q000378:metabolism*; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D008050:Lipid A; D000217:Acyltransferases