4578-22-7Relevant articles and documents
Structure of the unusual Sinorhizobium fredii HH103 lipopolysaccharide and its role in symbiosis
Di Lorenzo, Flaviana,Speciale, Immacolata,Silipo, Alba,Alías-Villegas, Cynthia,Acosta-Jurado, Sebastián,Rodríguez-Carvajal, Miguel-ángel,Dardanelli, Marta S.,Palmigiano, Angelo,Garozzo, Domenico,Ruiz-Sainz, José-Enrique,Molinaro, Antonio,Vinardell, José-María
, p. 10969 - 10987 (2021/01/07)
Rhizobia are soil bacteria that form important symbiotic associations with legumes, and rhizobial surface polysaccharides, such as K-antigen polysaccharide (KPS) and lipopolysaccharide (LPS), might be important for symbiosis. Previously, we obtained a mutant of Sinorhizobium fredii HH103, rkpA, that does not produce KPS, a homopolysaccharide of a pseudaminic acid derivative, but whose LPS electrophoretic profile was indistinguishable from that of the WT strain. We also previously demonstrated that the HH103 rkpLMNOPQ operon is responsible for 5-acetamido-3,5,7,9-tetradeoxy-7-(3-hydroxybutyramido)-L-glyc-ero-L-manno-nonulosonic acid [Pse5NAc7(3OHBu)] production and is involved in HH103 KPS and LPS biosynthesis and that an HH103 rkpM mutant cannot produce KPS and displays an altered LPS structure. Here, we analyzed the LPS structure of HH103 rkpA, focusing on the carbohydrate portion, and found that it contains a highly heterogeneous lipid A and a peculiar core oligosaccharide composed of an unusually high number of hexuronic acids containing b-configured Pse5NAc7(3OHBu). This pseudaminic acid derivative, in its a-configuration, was the only structural component of the S. fredii HH103 KPS and, to the best of our knowledge, has never been reported from any other rhizobial LPS. We also show that Pse5NAc7(3OHBu) is the complete or partial epitope for a mAb, NB6-228.22, that can recognize the HH103 LPS, but not those of most of the S. fredii strains tested here. We also show that the LPS from HH103 rkpM is identical to that of HH103 rkpA but devoid of any Pse5NAc7(3OHBu) residues. Notably, this rkpM mutant was severely impaired in symbiosis with its host, Macroptilium atropurpureum.
Structural elucidation, antioxidant and immunomodulatory activities of a novel heteropolysaccharide from cultured Paecilomyces cicadae (Miquel.) Samson
Wang, Yanbin,He, Pengfei,He, Liang,Huang, Qingrong,Cheng, Junwen,Li, Weiqi,Liu, Yu,Wei, Chaoyang
, p. 270 - 281 (2019/04/17)
The fine structure and chain conformation of a heteropolysaccharide (PCIPS3) from mycelium of Paecilomyces cicadae were investigated via the analysis of HPLC, IR, methylation, NMR spectroscopy and multiangle light scattering. It was determined to be a 2.23 × 104 g/mol heteropolysaccharide primarily composed of glucose, galactose and mannose in a molar ratio of 23.8:2.1:1.0. The PCIPS3 backbone consisted of 1,4-linked α-D-Glcp and 1,4-linked 6-O-Me-α-D-Glcp residues, which were occasionally interrupted by branched β-Galf residues through 1,6-linkage. Moreover, the α (0.60) from Mark–Houwink–Sakurada (MHS) equation suggested that PCIPS3 adopted a flexible chain conformation in 0.1 mol/L NaNO3 at 25 °C. The worm-like chains model parameters for PCIPS3 were estimated as following: ML = 437 nm?1, q = 0.46 nm and 0.79 nm, which were further evidenced by AFM. Furthermore, PCIPS3 showed excellent scavenging capacities of 2,2-diphenyl-1-picrylhydrazyl radical, superoxide radical, hydroxyl radical, ORAC radical and moderate immunomodulatory activity.
Bioengineering of Leuconostoc mesenteroides glucansucrases that gives selected bond formation for glucan synthesis and/or acceptor-product synthesis
Kang, Hee Kyoung,Kimura, Atsuo,Kim, Doman
experimental part, p. 4148 - 4155 (2011/10/30)
The variations in glucosidic linkage specificity observed in products of different glucansucrases appear to be based on relatively small differences in amino acid sequences in their sugar-binding acceptor subsites. Various amino acid mutations near active sites of DSRBCB4 dextransucrase from Leuconostoc mesenteroides B-1299CB4 were constructed. A triple amino acid mutation (S642N/E643N/V644S) immediately next to the catalytic D641 (putative transition state stabilizing residue) converted DSRBCB4 enzyme from the synthesis of mainly α-(1→6) dextran to the synthesis of α-(1→6) glucan containing branches of α-(1→3) and α-(1→4) glucosidic linkages. The subsequent introduction of mutation V532P/V535I, located next to the catalytic D530 (nucleophile), resulted in the synthesis of an α-glucan containing increased branched α-(1→4) glucosidic linkages (approximately 11%). The results indicate that mutagenesis can guide glucansucrase toward the synthesis of various oligosaccharides or novel polysaccharides with completely altered linkages without compromising high transglycosylation activity and efficiency.
