Kdo residues are widely distributed in bacteria.They are components of bacterial lipopolysaccharide(LPS)and capsular polysaccharides,which can be recognized by the human adaptive immune system,and have great potential...Kdo residues are widely distributed in bacteria.They are components of bacterial lipopolysaccharide(LPS)and capsular polysaccharides,which can be recognized by the human adaptive immune system,and have great potential for developing new sugar chips and antibacterial vaccines.By improving the existing methods,we optimized the Kdo chemical synthesis method,which was able to efficiently synthesize Kdo monosaccharides with high purity,laying a foundation for the construction of subsequent compound libraries.Kdo acylation can easily form 1,5-lactones and reduce the efficiency of synthesis.By changing the synthesis sequence,we avoided the formation of Kdo 1,5-lactones,improved the synthesis efficiency of Kdo glycals,and provided a new strategy for derivatization.展开更多
Dear Editor, Gram-negative bacteria utilize the acid sugar 2-keto-3-deoxymanno-octulosonic acid （Kdo） as an essential component of the lipopolysaccharide （LPS）. The enzyme CMP-Kdo synthetase （KdsB） is required ...Dear Editor, Gram-negative bacteria utilize the acid sugar 2-keto-3-deoxymanno-octulosonic acid （Kdo） as an essential component of the lipopolysaccharide （LPS）. The enzyme CMP-Kdo synthetase （KdsB） is required to activate Kdo prior to incorporation into the LPS, utilizing Kdo and CTP to form CMP-Kdo and pyrophosphate.展开更多
Understanding how the diversity of glycolipids,including how their chemical structures and composition affect their biological functions,is a remarkable fundamental challenge.In this work,we employed a rare monosaccha...Understanding how the diversity of glycolipids,including how their chemical structures and composition affect their biological functions,is a remarkable fundamental challenge.In this work,we employed a rare monosaccharide,3-deoxy-Dmanno-2-octulosonic acid(Kdo)to build a simple and biomimetic model to understand the diversity of glycolipids from the viewpoint of supramolecular chemistry.Kdo was chosen not only because its unusual 8-carbon acidic carbohydrate backbone is very different from common hexoses,but also because of its key structural role in lipopolysaccharides and prevalence in bacteria,plant life,and algae.It was found that although both of the two Kdo-lipids S-Kdo and Kdo-S derived from the same carbohydrate backbone and gave bicelles as their self-assembled morphology,experimental results revealed that the self-assembly showed pathway complexity.Bicelle is the thermodynamic product of S-Kdo,while for Kdo-S,the bicelle is only a kinetically trapped state,which finally transforms to a ribbon.Molecular simulation clearly revealed the different packing of Kdo-lipids in the bicelles with different contribution from hydrogen bonds and electrostatic interactions.展开更多
Escherichia coli 3-Deoxy-D-manno-octulosonate 8-phosphate（KDO8P） synthase catalyzed the condensation reaction between D-arabinose 5-phosphate（A5P） and phosphoenolpyruvate（PEP） to form KDO8P and inorganic phosph...Escherichia coli 3-Deoxy-D-manno-octulosonate 8-phosphate（KDO8P） synthase catalyzed the condensation reaction between D-arabinose 5-phosphate（A5P） and phosphoenolpyruvate（PEP） to form KDO8P and inorganic phosphate（Pi）. The noncovalent tetrameric association ofKDO8P synthase was observed and dissociated in gas phase by means of electrospray ionization mass spectrometry under the very ＂soft＂ conditions. The results indicate that PEP-bound enzyme generated abundant tetrameric species as well as monomeric species at the ＂soft＂ conditions, whereas, the unbound enzyme favored the formation of a dimeric species. The mass spectra of the mixture of the enzyme with one of substrates, PEP, and A5P or one of products, KDO8P and Pi show that the complex of the unbound enzyme with PEP or Pi was prone to the formation of a monomeric species, whereas, that of the unbound enzyme with A5P or KDO8P was similar to the unbound enzyme. The intensity of the dimeric species increased with the increase of temperature at a collision voltage of 10 V. Taken together, the results presented here suggest that mass spectrometry will be a powerful tool to explore subtile conformational changes and/or subunit-subunit interactions of multiprotein assembly induced by ligand-binding and/or the changes of environmental conditions.展开更多
基金National Natural Science Foundation of China(Grant No.81930097,21977005)。
文摘Kdo residues are widely distributed in bacteria.They are components of bacterial lipopolysaccharide(LPS)and capsular polysaccharides,which can be recognized by the human adaptive immune system,and have great potential for developing new sugar chips and antibacterial vaccines.By improving the existing methods,we optimized the Kdo chemical synthesis method,which was able to efficiently synthesize Kdo monosaccharides with high purity,laying a foundation for the construction of subsequent compound libraries.Kdo acylation can easily form 1,5-lactones and reduce the efficiency of synthesis.By changing the synthesis sequence,we avoided the formation of Kdo 1,5-lactones,improved the synthesis efficiency of Kdo glycals,and provided a new strategy for derivatization.
文摘Dear Editor, Gram-negative bacteria utilize the acid sugar 2-keto-3-deoxymanno-octulosonic acid （Kdo） as an essential component of the lipopolysaccharide （LPS）. The enzyme CMP-Kdo synthetase （KdsB） is required to activate Kdo prior to incorporation into the LPS, utilizing Kdo and CTP to form CMP-Kdo and pyrophosphate.
基金the financial support from the National Natural Science Foundation of China(grant nos.51721002,21861132012,91956127,and 21975047)NSFC/China(grant nos.21674114 and 91956127)for financial supportsupported by the Shanghai Municipal Science and Technology Major Project(grant no.2018SHZDZX01)and ZJ Lab.
文摘Understanding how the diversity of glycolipids,including how their chemical structures and composition affect their biological functions,is a remarkable fundamental challenge.In this work,we employed a rare monosaccharide,3-deoxy-Dmanno-2-octulosonic acid(Kdo)to build a simple and biomimetic model to understand the diversity of glycolipids from the viewpoint of supramolecular chemistry.Kdo was chosen not only because its unusual 8-carbon acidic carbohydrate backbone is very different from common hexoses,but also because of its key structural role in lipopolysaccharides and prevalence in bacteria,plant life,and algae.It was found that although both of the two Kdo-lipids S-Kdo and Kdo-S derived from the same carbohydrate backbone and gave bicelles as their self-assembled morphology,experimental results revealed that the self-assembly showed pathway complexity.Bicelle is the thermodynamic product of S-Kdo,while for Kdo-S,the bicelle is only a kinetically trapped state,which finally transforms to a ribbon.Molecular simulation clearly revealed the different packing of Kdo-lipids in the bicelles with different contribution from hydrogen bonds and electrostatic interactions.
基金Supported by National Hi-tech Research and Development Program of China(No.2006AA02Z154)the National Natural Science Foundation of China(No.20675088) and SRF for ROCS, SEM, China
文摘Escherichia coli 3-Deoxy-D-manno-octulosonate 8-phosphate（KDO8P） synthase catalyzed the condensation reaction between D-arabinose 5-phosphate（A5P） and phosphoenolpyruvate（PEP） to form KDO8P and inorganic phosphate（Pi）. The noncovalent tetrameric association ofKDO8P synthase was observed and dissociated in gas phase by means of electrospray ionization mass spectrometry under the very ＂soft＂ conditions. The results indicate that PEP-bound enzyme generated abundant tetrameric species as well as monomeric species at the ＂soft＂ conditions, whereas, the unbound enzyme favored the formation of a dimeric species. The mass spectra of the mixture of the enzyme with one of substrates, PEP, and A5P or one of products, KDO8P and Pi show that the complex of the unbound enzyme with PEP or Pi was prone to the formation of a monomeric species, whereas, that of the unbound enzyme with A5P or KDO8P was similar to the unbound enzyme. The intensity of the dimeric species increased with the increase of temperature at a collision voltage of 10 V. Taken together, the results presented here suggest that mass spectrometry will be a powerful tool to explore subtile conformational changes and/or subunit-subunit interactions of multiprotein assembly induced by ligand-binding and/or the changes of environmental conditions.
