3-Deoxy-D-manno–oct-2-ulosonic acid(Kdo)is widely distributed in bacteria,and the synthesis of Kdocontaining oligosaccharides is important for the development of novel antibiotics and immunological agents.We have rec...3-Deoxy-D-manno–oct-2-ulosonic acid(Kdo)is widely distributed in bacteria,and the synthesis of Kdocontaining oligosaccharides is important for the development of novel antibiotics and immunological agents.We have recently developed a strategy to achieveα-stereocontrolled glycosylation using a C3-p-tolylthio-substituted Kdo phosphite donor.The wide substrate scope and high reactivity of the donors enabled the efficient synthesis of a series of Kdo-containing glycosides with completeα-stereoselectivity and without the formation of 2,3-ene byproducts.In this study,we improved the method by replacing the leaving group diethyl phosphite with fluoride,which enhanced the stability of the donor and led to cleaner reaction.Furthermore,the substrate range was expanded by synthesizing a series of Kdo O/C/S/Nglycosides,which also opened up a new avenue for the synthesis of CMP-Kdo synthase inhibitors.展开更多
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
The human intestinal symbiotic microorganism Bacteroides thetaiotaomicron has a unique lipooligosaccharide structure,which promotes its beneficial symbiosis with the host.But its synthesis mechanism is not fully under...The human intestinal symbiotic microorganism Bacteroides thetaiotaomicron has a unique lipooligosaccharide structure,which promotes its beneficial symbiosis with the host.But its synthesis mechanism is not fully understood.In this study,protein sequence alignment revealed that the protein encoded by B.thetaiotaomicron VPI 5482 BT_2747 gene shares 24%sequence identity with Escherichia coli WaaA.The expression vector was used to overexpress BT_2747 in E.coli lipopolysaccharide mutant strains constructed by knocking out the waaC-waaF,lpxL or lpxM genes,resulting in the recombinant strains WH001(ΔwaaA)/pBT2747,WL003(ΔwaaAwaaC-F)/pBT2747,WL004(ΔwaaAwaaC-FlpxL)/pBT2747,WL005(ΔwaaAwaaC-FlpxM)/pBT2747 and WL006(ΔwaaAwaaC-FlpxLlpxM)/pBT2747.Lipid A/Kdo-lipid A were extracted from these recombinant strains and analyzed by liquid chromatography-mass spectrometry.The results showed that BT_2747 could convert a portion of the lipid IVA into Kdo-lipid IVA,but no Kdo2-lipid IVA structure was detected in E.coli.Small amounts of hexa-acylated Kdo-lipid A were also detected in the recombinant strains WH001/pBT2747 and WL003/pBT2747,and a small amount of penta-acylated Kdo-lipid A was found in WL004/pBT2747.The recombinant strain was further modified by introducing lpxF that enabled to synthesize Kdo-lipid IVA-1-phosphate.The results revealed that the BT_2747 gene in B.thetaiotaomicron VPI 5482 encodes the Kdo transferase of lipid A which uses lipid IVA as a substrate and only transfers single Kdo residue to lipid IVA.This study extends our understanding of the Kdo-lipid A structure and synthesis mechanism of B.thetaiotaomicron,which might provide a new perspective on how intestinal commensal bacteria regulate host immune homeostasis through unique Kdo-lipid A structure.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
基金supported by the National Key R&D Program of China(Nos.2022YFF1203005,2022YFC2303700)supported by the National Natural Science Foundation of China(Nos.81930097,82151223).
文摘3-Deoxy-D-manno–oct-2-ulosonic acid(Kdo)is widely distributed in bacteria,and the synthesis of Kdocontaining oligosaccharides is important for the development of novel antibiotics and immunological agents.We have recently developed a strategy to achieveα-stereocontrolled glycosylation using a C3-p-tolylthio-substituted Kdo phosphite donor.The wide substrate scope and high reactivity of the donors enabled the efficient synthesis of a series of Kdo-containing glycosides with completeα-stereoselectivity and without the formation of 2,3-ene byproducts.In this study,we improved the method by replacing the leaving group diethyl phosphite with fluoride,which enhanced the stability of the donor and led to cleaner reaction.Furthermore,the substrate range was expanded by synthesizing a series of Kdo O/C/S/Nglycosides,which also opened up a new avenue for the synthesis of CMP-Kdo synthase inhibitors.
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.
基金funded by the Basic Research Program of Jiangsu and supported by the Jiangsu Basic Research Center for Synthetic Biology(Grant No.BK20233003)by National Natural Science Foundation of China(NSFC32270102).
文摘The human intestinal symbiotic microorganism Bacteroides thetaiotaomicron has a unique lipooligosaccharide structure,which promotes its beneficial symbiosis with the host.But its synthesis mechanism is not fully understood.In this study,protein sequence alignment revealed that the protein encoded by B.thetaiotaomicron VPI 5482 BT_2747 gene shares 24%sequence identity with Escherichia coli WaaA.The expression vector was used to overexpress BT_2747 in E.coli lipopolysaccharide mutant strains constructed by knocking out the waaC-waaF,lpxL or lpxM genes,resulting in the recombinant strains WH001(ΔwaaA)/pBT2747,WL003(ΔwaaAwaaC-F)/pBT2747,WL004(ΔwaaAwaaC-FlpxL)/pBT2747,WL005(ΔwaaAwaaC-FlpxM)/pBT2747 and WL006(ΔwaaAwaaC-FlpxLlpxM)/pBT2747.Lipid A/Kdo-lipid A were extracted from these recombinant strains and analyzed by liquid chromatography-mass spectrometry.The results showed that BT_2747 could convert a portion of the lipid IVA into Kdo-lipid IVA,but no Kdo2-lipid IVA structure was detected in E.coli.Small amounts of hexa-acylated Kdo-lipid A were also detected in the recombinant strains WH001/pBT2747 and WL003/pBT2747,and a small amount of penta-acylated Kdo-lipid A was found in WL004/pBT2747.The recombinant strain was further modified by introducing lpxF that enabled to synthesize Kdo-lipid IVA-1-phosphate.The results revealed that the BT_2747 gene in B.thetaiotaomicron VPI 5482 encodes the Kdo transferase of lipid A which uses lipid IVA as a substrate and only transfers single Kdo residue to lipid IVA.This study extends our understanding of the Kdo-lipid A structure and synthesis mechanism of B.thetaiotaomicron,which might provide a new perspective on how intestinal commensal bacteria regulate host immune homeostasis through unique Kdo-lipid A structure.
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.
