51883-36-4Relevant 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.
Asymmetric reduction of monoketo hexadecanoic acid methyl esters
Türker, Gülen,Yusufoglu, Ayse
, p. 1531 - 1535 (2013/06/26)
Methyl 2-,3-,6-,8-,14- and 15-keto hexadecanoates were reduced by using NaBH4 in presence of 1,2;5,6-di-O-isopropilydene-Dglucofuranose [DIPGH], R(+)-1,1′-binaphthyl-2,2′-diol [RBND] and pivalic acid [PA]. The reduction of 2- and 3-keto esters in the presence of (+)-1,1′-binaphthyl-2,2′-diol results in considerably higher stereoselectivities (95 % ee). Enantiometric excess (ee %) was determined by 1H and 13C NMR analyses using a shift reagent, Eu(tfc)3. Copyright
Termination of the structural confusion between plipastatin A1 and fengycin IX
Honma, Miho,Tanaka, Kazuaki,Konno, Katsuhiro,Tsuge, Kenji,Okuno, Toshikatsu,Hashimoto, Masaru
experimental part, p. 3793 - 3798 (2012/08/28)
Plipastatin A1 and fengycin IX were experimentally proven to be identical compounds, while these had been considered as diastereomers due to the permutation of the enantiomeric pair of Tyr in most papers. The 1H NMR spectrum changed to become quite similar to that of plipastatin A1, when the sample which provided resembled spectrum of fengycin IX was treated with KOAc followed by LH-20 gel filtration. Our structural investigations disclosed that the structures of these molecules should be settled into that of plipastatin A1 by Umezawa (l-Tyr4 and d-Tyr10).
