Dental caries is one of the most common chronic diseases and is caused by acid fermentation of bacteria adhered to the teeth. Streptococcus mutans （S. mutans） utilizes sortase A （SrtA） to anchor surface proteins t...Dental caries is one of the most common chronic diseases and is caused by acid fermentation of bacteria adhered to the teeth. Streptococcus mutans （S. mutans） utilizes sortase A （SrtA） to anchor surface proteins to the cell wall and forms a biofilm to facilitate its adhesion to the tooth surface. Some plant natural products, especially several flavonoids, are effective inhibitors of SrtA. However, given the limited number of inhibitors and the development of drug resistance, the discovery of new inhibitors is urgent. Here, the high-throughput virtual screening approach was performed to identify new potential inhibitors of S. mutans SrtA. Two libraries were used for screening, and nine compounds that had the lowest scores were chosen for further molecular dynamics simulation, binding free energy analysis and absorption, distribution, metabolism, excretion and toxicity （ADMET） properties analysis. The results revealed that several similar compounds composed of benzofuran, thiadiazole and pyrrole, which exhibited good affinities and appropriate pharmacokinetic In addition, the carbonyl of these compounds can have a strategy for microbial infection disease therapy. parameters, were potential inhibitors to impede the catalysis of SrtA. key role in the inhibition mechanism. These findings can provide a new展开更多
Streptococcus mutans is a common Gram-positive bacterium and plays a significant role in dental caries. Tobacco and/or nicotine have documented effects on S. mutans growth and colonization. Sortase A is used by many G...Streptococcus mutans is a common Gram-positive bacterium and plays a significant role in dental caries. Tobacco and/or nicotine have documented effects on S. mutans growth and colonization. Sortase A is used by many Gram-positive bacteria, including S. mutans, to facilitate the insertion of certain cell surface proteins, containing an LPXTGX motif such as antigen 1/11. This study examined the effect of nicotine on the function of sortase A to control the physiology and growth of S. mutans using wild-type S. mutans NG8, and its isogenic sortase-defective and -complemented strains. Briefly, the strains were treated with increasing amounts of nicotine in planktonic growth, biofilm metabolism, and sucrose-induced and saliva-induced antigen I/ll-dependent biofilm formation assays. The strains exhibited no significant differences with different concentrations of nicotine in planktonic growth assays. However, they had significantly increased （P~〈 0.05） biofilm metabolic activity （2- to 3-fold increase） as the concentration of nicotine increased. Furthermore, the sortase-defective strain was more sensitive metabolically to nicotine than the wild-type or sortase-complemented strains. All strains had significantly increased sucrose-induced biofilm formation （2- to 3-fold increase） as a result of increasing concentrations of nicotine. However, the sortase-defective strain was not able to make as much sucrose- and saliva-induced biofilm as the wild-type NG8 did with increasing nicotine concentrations. These results indicated that nicotine increased metabolic activity and sucrose-induced biofilm formation. The saliva-induced biofilm formation assay and qPCR data suggested that antigen 1/11 was upregulated with nicotine but biofilm was not able to be formed as much as wild-type NG8 without functional sortase A.展开更多
Insulin derivatives such as insulin detemir and insulin degludec are U.S.Food and Drug Administration(FDA)-approved long-acting insulin currently used by millions of people with diabetes.These derivatives are modified...Insulin derivatives such as insulin detemir and insulin degludec are U.S.Food and Drug Administration(FDA)-approved long-acting insulin currently used by millions of people with diabetes.These derivatives are modified in C-terminal B29 lysine to retain insulin bioactivity.New and efficient methods for facile synthesis of insulin derivatives may lead to new discovery of therapeutic insulin.Herein,we report a new method using sortase A(SrtA)-mediated ligation for the synthesis of insulin derivatives with high efficiency and functional group tolerance in the C-terminal B chain.This new insulin molecule(Ins-SA) with an SrtA-recognizing motif can be conjugated to diverse groups with N-terminal oligoglycines to generate new insulin derivatives.We further demonstrated that a new insulin derivative synthesized by this SrtA-mediated ligation shows strong cellular and in vivo bioactivity.This enzymatic method can therefore be used for future insulin design and development.展开更多
P-113 is a fragment of natural occurring peptide Histatin 5 found in human saliva. This peptide exhibited broad spectrum of antibacterial and antifungal biological activities. In this study, bifunctional P-113 peptide...P-113 is a fragment of natural occurring peptide Histatin 5 found in human saliva. This peptide exhibited broad spectrum of antibacterial and antifungal biological activities. In this study, bifunctional P-113 peptides 2–5 were designed as Sortase A substrates and synthesized by solid support peptide synthesis,where the N-terminus were equipped with glycine and its analogues, and C-terminus were extended with LPETGGS, respectively. Under Sortase A catalyzed condition, head to tail cyclization products 7–10were afforded in yields from 76% to 93%. The conformation insights of linear peptides 2–5 and cyclic analogues 7–10 in aqueous buffers and in trifluroethanol（TFE） analyzed by circular dichroism（CD）suggested that a-helix structures were produced progressively in hydrophobic environment independent of the cyclization, which displayed the similar behavior as parent peptide P-113.展开更多
This study aimed to study whether the Sortase A（srt A） gene helps mediate coaggregation and co-adherence between Streptococcus mutans（S.mutans） and other salivary bacteria.S.mutans UA159 and srt A-deficient mutant...This study aimed to study whether the Sortase A（srt A） gene helps mediate coaggregation and co-adherence between Streptococcus mutans（S.mutans） and other salivary bacteria.S.mutans UA159 and srt A-deficient mutant served as ＂bait＂ in classical co-aggregation assays and membrane-based co-adherence assays were used to examine interactions of S.mutans with Fusobacterium nucleatum（F.nucleatum）,Streptococcus mitis（S.mitis）,Streptococcus gordonii（S.gordonii）,Streptococcus sanguis（S.sanguis）,Actinomyces naeslundii（A.naeslundii） and Lactobacillus.Co-adherence assays were also performed using unfractionated saliva from healthy individuals.Co-adhering partners of S.mutans were sensitively detected using polymerase chain reaction-denaturing gradient gel electrophoresis（PCR-DGGE）.Both UA159 and its srt A-deficient mutant bound to F.nucleatum but not to any of the other five salivary bacteria.The srt A-deficient mutant showed lower co-adherence with F.nucleatum.The two S.mutans strains also showed similar co-adherence profiles against unfractionated salivary bacteria,except that UA159 S.mutans but not the srt A-deficient bound to a Neisseria sp.under the same conditions.Deleting srt A reduces the ability of S.mutans to bind to F.nucleatum,but it does not appear to significantly affect the binding profile of S.mutans to bulk salivary bacteria.Key words展开更多
基金supported in part by the National Natural Science Foundation of China (Nos 31300674,81173093,30970643,81373311 and J1103518)the Special Programme for Youth Science and the Technology Innovative Research Group of Sichuan Province,China (No 2011JTD0026)
文摘Dental caries is one of the most common chronic diseases and is caused by acid fermentation of bacteria adhered to the teeth. Streptococcus mutans （S. mutans） utilizes sortase A （SrtA） to anchor surface proteins to the cell wall and forms a biofilm to facilitate its adhesion to the tooth surface. Some plant natural products, especially several flavonoids, are effective inhibitors of SrtA. However, given the limited number of inhibitors and the development of drug resistance, the discovery of new inhibitors is urgent. Here, the high-throughput virtual screening approach was performed to identify new potential inhibitors of S. mutans SrtA. Two libraries were used for screening, and nine compounds that had the lowest scores were chosen for further molecular dynamics simulation, binding free energy analysis and absorption, distribution, metabolism, excretion and toxicity （ADMET） properties analysis. The results revealed that several similar compounds composed of benzofuran, thiadiazole and pyrrole, which exhibited good affinities and appropriate pharmacokinetic In addition, the carbonyl of these compounds can have a strategy for microbial infection disease therapy. parameters, were potential inhibitors to impede the catalysis of SrtA. key role in the inhibition mechanism. These findings can provide a new
文摘Streptococcus mutans is a common Gram-positive bacterium and plays a significant role in dental caries. Tobacco and/or nicotine have documented effects on S. mutans growth and colonization. Sortase A is used by many Gram-positive bacteria, including S. mutans, to facilitate the insertion of certain cell surface proteins, containing an LPXTGX motif such as antigen 1/11. This study examined the effect of nicotine on the function of sortase A to control the physiology and growth of S. mutans using wild-type S. mutans NG8, and its isogenic sortase-defective and -complemented strains. Briefly, the strains were treated with increasing amounts of nicotine in planktonic growth, biofilm metabolism, and sucrose-induced and saliva-induced antigen I/ll-dependent biofilm formation assays. The strains exhibited no significant differences with different concentrations of nicotine in planktonic growth assays. However, they had significantly increased （P~〈 0.05） biofilm metabolic activity （2- to 3-fold increase） as the concentration of nicotine increased. Furthermore, the sortase-defective strain was more sensitive metabolically to nicotine than the wild-type or sortase-complemented strains. All strains had significantly increased sucrose-induced biofilm formation （2- to 3-fold increase） as a result of increasing concentrations of nicotine. However, the sortase-defective strain was not able to make as much sucrose- and saliva-induced biofilm as the wild-type NG8 did with increasing nicotine concentrations. These results indicated that nicotine increased metabolic activity and sucrose-induced biofilm formation. The saliva-induced biofilm formation assay and qPCR data suggested that antigen 1/11 was upregulated with nicotine but biofilm was not able to be formed as much as wild-type NG8 without functional sortase A.
基金supported by NIGMS(GM125001,USA)NIDDK(DK121336,USA)
文摘Insulin derivatives such as insulin detemir and insulin degludec are U.S.Food and Drug Administration(FDA)-approved long-acting insulin currently used by millions of people with diabetes.These derivatives are modified in C-terminal B29 lysine to retain insulin bioactivity.New and efficient methods for facile synthesis of insulin derivatives may lead to new discovery of therapeutic insulin.Herein,we report a new method using sortase A(SrtA)-mediated ligation for the synthesis of insulin derivatives with high efficiency and functional group tolerance in the C-terminal B chain.This new insulin molecule(Ins-SA) with an SrtA-recognizing motif can be conjugated to diverse groups with N-terminal oligoglycines to generate new insulin derivatives.We further demonstrated that a new insulin derivative synthesized by this SrtA-mediated ligation shows strong cellular and in vivo bioactivity.This enzymatic method can therefore be used for future insulin design and development.
基金supported by the National Natural Science Foundation of China(No.21472070)the Project for Jiangsu Scientific and Technological Innovation Team+2 种基金Fund for Jiangsu Distinguished Professorship ProgramProject Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,the 111 Project(No.111-2-06)the Jiangsu province“Collaborative Innovation Center for Advanced Industrial Fermentation”industry development program
文摘P-113 is a fragment of natural occurring peptide Histatin 5 found in human saliva. This peptide exhibited broad spectrum of antibacterial and antifungal biological activities. In this study, bifunctional P-113 peptides 2–5 were designed as Sortase A substrates and synthesized by solid support peptide synthesis,where the N-terminus were equipped with glycine and its analogues, and C-terminus were extended with LPETGGS, respectively. Under Sortase A catalyzed condition, head to tail cyclization products 7–10were afforded in yields from 76% to 93%. The conformation insights of linear peptides 2–5 and cyclic analogues 7–10 in aqueous buffers and in trifluroethanol（TFE） analyzed by circular dichroism（CD）suggested that a-helix structures were produced progressively in hydrophobic environment independent of the cyclization, which displayed the similar behavior as parent peptide P-113.
基金supported by grants from the National Natural Science Foundation of China(No.81570974)the Key Project of the Science and Technology Department of Sichuan Province(No.2015JY0260)
文摘This study aimed to study whether the Sortase A（srt A） gene helps mediate coaggregation and co-adherence between Streptococcus mutans（S.mutans） and other salivary bacteria.S.mutans UA159 and srt A-deficient mutant served as ＂bait＂ in classical co-aggregation assays and membrane-based co-adherence assays were used to examine interactions of S.mutans with Fusobacterium nucleatum（F.nucleatum）,Streptococcus mitis（S.mitis）,Streptococcus gordonii（S.gordonii）,Streptococcus sanguis（S.sanguis）,Actinomyces naeslundii（A.naeslundii） and Lactobacillus.Co-adherence assays were also performed using unfractionated saliva from healthy individuals.Co-adhering partners of S.mutans were sensitively detected using polymerase chain reaction-denaturing gradient gel electrophoresis（PCR-DGGE）.Both UA159 and its srt A-deficient mutant bound to F.nucleatum but not to any of the other five salivary bacteria.The srt A-deficient mutant showed lower co-adherence with F.nucleatum.The two S.mutans strains also showed similar co-adherence profiles against unfractionated salivary bacteria,except that UA159 S.mutans but not the srt A-deficient bound to a Neisseria sp.under the same conditions.Deleting srt A reduces the ability of S.mutans to bind to F.nucleatum,but it does not appear to significantly affect the binding profile of S.mutans to bulk salivary bacteria.Key words
