Nigerooligosaccharides (NOS) is a new functional oligosaccharide containing α-1,3 glucosidic bond with good anti-digestive properties and intestinal probiotics.Transglycosylation catalyzed by α-glucosidase is an eff...Nigerooligosaccharides (NOS) is a new functional oligosaccharide containing α-1,3 glucosidic bond with good anti-digestive properties and intestinal probiotics.Transglycosylation catalyzed by α-glucosidase is an effective method for the preparation of oligosaccharides.However,there are few reports on the enzymatic synthesis of nigerooligosaccharides by α-glucosidase at present.This study was aimed to investigate the transglycosylation property of the GH31 α-glucosidase from Thermoplasma acidophilum,TaAglA,and also evaluate its application performance in the preparation of NOS.It was found that TaAglA exhibited selectivity for α-1,3 and α-1,4 linkages when catalyzing hydrolysis,but for α-1,3 and α-1,6 linkages when catalyzing transglycosylation.Using 10% glucose and 20% maltose as substrates,TaAglA yielded 88.5 g/L NOS under the condition of pH 6.0,80 ℃ and 1 U/mL enzyme addition,which was the highest level to our knowledge.In addition,components with higher polymerization degrees,i.e.nigerotriose and nigerosyl-glucose,occupied 53.6% proportion of the total NOS products,giving it better probiotic functions.Futhermore,after purification by glucoamylase digestion and yeast culture,the final yield of NOS was 26.1%,and the purity of the product was 93%.These findings on TaAglA were expected to provide a new candidate for large-scale enzymatic synthesis of NOS,and also have important theoretical significance for the study of GH31 α-glucosidase.展开更多
The microdomains of plasmodesmata,specialized cell-wall channels responsible for communications between neighboring cells,are composed of various plasmodesmata-located proteins(PDLPs)and lipids.Here,we found that,amon...The microdomains of plasmodesmata,specialized cell-wall channels responsible for communications between neighboring cells,are composed of various plasmodesmata-located proteins(PDLPs)and lipids.Here,we found that,among all PDLP or homologous proteins in Arabidopsis thaliana genome,PDLP5 and PDLP7 possessed a C-terminal sphingolipid-binding motif,with the latter being the only member that was significantly upregulated upon turnip mosaic virus and cucumber mosaic virus infections.pdlp7mutant plants exhibited significantly reduced callose deposition,larger plasmodesmata diameters,and faster viral transmission.These plants exhibited increased glucosidase activity but no change in callose synthase activity.PDLP7 interacted specifically with glucan endo-1,3-β-glucosidase 10(BG10).Consistently,higher levels of callose deposition and slower virus transmission in bg10 mutants were observed.The interaction between PDLP7 and BG10 was found to depend on the presence of the Gnk2-homologous 1(Gn K2-1)domain at the N terminus of PDLP7 with Asp-35,Cys-42,Gln-44,and Leu-116 being essential.In vitro supplementation of callose was able to change the conformation of the Gn K2-1 domain.Our data suggest that the Gn K2-1 domain of PDLP7,in conjunction with callose and BG10,plays a key role in plasmodesmata opening and closure,which is necessary for intercellular movement of various molecules.展开更多
基金supported by grants from the National Natural Science Foundation of China(31730067,31801472)the Natural Science Foundation of Jiangsu Province(BK20180604)the national first-class discipline program of Light Industry Technology and Engineering(LITE2018-03).
文摘Nigerooligosaccharides (NOS) is a new functional oligosaccharide containing α-1,3 glucosidic bond with good anti-digestive properties and intestinal probiotics.Transglycosylation catalyzed by α-glucosidase is an effective method for the preparation of oligosaccharides.However,there are few reports on the enzymatic synthesis of nigerooligosaccharides by α-glucosidase at present.This study was aimed to investigate the transglycosylation property of the GH31 α-glucosidase from Thermoplasma acidophilum,TaAglA,and also evaluate its application performance in the preparation of NOS.It was found that TaAglA exhibited selectivity for α-1,3 and α-1,4 linkages when catalyzing hydrolysis,but for α-1,3 and α-1,6 linkages when catalyzing transglycosylation.Using 10% glucose and 20% maltose as substrates,TaAglA yielded 88.5 g/L NOS under the condition of pH 6.0,80 ℃ and 1 U/mL enzyme addition,which was the highest level to our knowledge.In addition,components with higher polymerization degrees,i.e.nigerotriose and nigerosyl-glucose,occupied 53.6% proportion of the total NOS products,giving it better probiotic functions.Futhermore,after purification by glucoamylase digestion and yeast culture,the final yield of NOS was 26.1%,and the purity of the product was 93%.These findings on TaAglA were expected to provide a new candidate for large-scale enzymatic synthesis of NOS,and also have important theoretical significance for the study of GH31 α-glucosidase.
基金supported by the National Natural Science Foundation of China(31830057)。
文摘The microdomains of plasmodesmata,specialized cell-wall channels responsible for communications between neighboring cells,are composed of various plasmodesmata-located proteins(PDLPs)and lipids.Here,we found that,among all PDLP or homologous proteins in Arabidopsis thaliana genome,PDLP5 and PDLP7 possessed a C-terminal sphingolipid-binding motif,with the latter being the only member that was significantly upregulated upon turnip mosaic virus and cucumber mosaic virus infections.pdlp7mutant plants exhibited significantly reduced callose deposition,larger plasmodesmata diameters,and faster viral transmission.These plants exhibited increased glucosidase activity but no change in callose synthase activity.PDLP7 interacted specifically with glucan endo-1,3-β-glucosidase 10(BG10).Consistently,higher levels of callose deposition and slower virus transmission in bg10 mutants were observed.The interaction between PDLP7 and BG10 was found to depend on the presence of the Gnk2-homologous 1(Gn K2-1)domain at the N terminus of PDLP7 with Asp-35,Cys-42,Gln-44,and Leu-116 being essential.In vitro supplementation of callose was able to change the conformation of the Gn K2-1 domain.Our data suggest that the Gn K2-1 domain of PDLP7,in conjunction with callose and BG10,plays a key role in plasmodesmata opening and closure,which is necessary for intercellular movement of various molecules.
