Transketolase （TK）, a thiamine diphosphate （ThDP）-dependent enzyme, catalyzes several key reactions of nonoxidative branch of pentose phosphate pathway. TK is a homodimer with two active sites that locate at the i...Transketolase （TK）, a thiamine diphosphate （ThDP）-dependent enzyme, catalyzes several key reactions of nonoxidative branch of pentose phosphate pathway. TK is a homodimer with two active sites that locate at the interface between the contacting monomers. Both ThDP and bivalent cations are strictly needed for TK activation, just like that for all ThDPdependent enzymes. TK exists in all organisms that have been investigated. Up to now, one TK gene （TKT） and two transketolase-like genes （TKTL1 and TKTL2） have been identified in human genome. TKTL1 is reported to play a pivotal role in carcinogenesis and may have important implications in the nutrition and future treatment of patients with cancer. Research- ers have found TK variants and reduced activities of TK enzyme in patients with neurodegenerative diseases, diabetes, and cancer. Recent studies indicated TK as a novel role in the prevention and therapy of these diseases.展开更多
Objective:To determine whether B vitamin treatment was sufficient to reduce cognitive impairment associated with high-fat diets in rats and to modulate transketolase(TK)expression and activity.Methods:To test this,we ...Objective:To determine whether B vitamin treatment was sufficient to reduce cognitive impairment associated with high-fat diets in rats and to modulate transketolase(TK)expression and activity.Methods:To test this,we separated 50 rats into five groups that were either fed a standard chow diet(controls)or a high-fat diet(experimental groups HO,HI,H2,and H3).HO group animals received no additional dietary supplementation,while H1 group animals were administered 100 mg/kg body weight(BW)thiamine,100 mg/kg BW riboflavin,and 250 mg/kg BW niacin each day,and group H2 animals received daily doses of 100 mg/kg BW pyridoxine,100 mg/kg BW cobalamin,and 5 mg/kg BW folate.Animals in the H3 group received the B vitamin regimens administered to both H1 and H2 each day.Results:Over time,group HO exhibited greater increases in BW and fat mass relative to other groups.When spatial and memory capabilities in these animals were evaluated via conditioned taste aversion(CTA)and Morris Water Maze(MWM),we found B vitamin treatment was associated with significant improvements relative to untreated HO controls.Similarly,B vitamin supplementation was associated with elevated TK expression in erythrocytes and hypothalamus of treated animals relative to those in HO(P<0.05).Conclusion:Together,these findings suggest B vitamin can modulate hypothalamic TK activity to reduce the severity of cognitive deficits in a rat model of obesity.As such,B vitamin supplementation may be a beneficial method for reducing cognitive dysfunction in clinical settings associated with high-fat diets.展开更多
Transketolase, the most critical enzyme of the non-oxidative branch of the pentose phosphate pathway, has been reported as a novel target in Plasmodium falciparum as it has least homology with the human host. Homology...Transketolase, the most critical enzyme of the non-oxidative branch of the pentose phosphate pathway, has been reported as a novel target in Plasmodium falciparum as it has least homology with the human host. Homology model of P. falciparum transketolase (PfTk) was constructed using the crystal structure of S. cervisiae transketolase as a template, and used for the identification and prioritization of potential compounds targeted against Plasmodium falciparum transketolase. The docking studies with fructose-6-phosphate and thiamine pyrophosphate showed that His31, Asp473, Ser388, Arg361 and His465 formed hydrogen bonds with fructose-6-phosphate while pyrimidine ring of coenzyme interacted with conserved residues of protein viz., Leu121, Glu415, Gly119. The major interacting residues involved in binding of oxythiamine pyrophosphate were similar to cofactor binding site of PfTk. An integrated pharmacophore, co-factor ThDP and substrate fructose-6-pho- sphate, based virtual screening of a small mo- lecule database retrieved eight and thirteen compounds respectively. When screened for their activity against P. falciparum transketolase, one compound in case of ThDP and three compounds in case of fructose-6-phosphate based screening were found active against PfTk. Identification of these novel and chemically diverse inhibitors provides initial leads for optimization of more potent and efficacious drug candidates to treat malarial infection.展开更多
Growing prevalence of diabetes(type 2 as well as type 1) and its related morbidity due to vascular complications creates a large burden on medical care worldwide. Understanding the molecular pathogenesis of chronic mi...Growing prevalence of diabetes(type 2 as well as type 1) and its related morbidity due to vascular complications creates a large burden on medical care worldwide. Understanding the molecular pathogenesis of chronic micro-, macro- and avascular complications mediated by hyperglycemia is of crucial importance since novel therapeutic targets can be identified and tested. Thiamine(vitamin B1) is an essential cofactor of several enzymes involved in carbohydrate metabolism and published data suggest that thiamine metabolism in diabetes is deficient. This review aims to point out the physiological role of thiamine in metabolism of glucose and amino acids, to present overview of thiamine metabolism and to describe the consequences of thiamine deficiency(either clinically manifest or latent). Furthermore, we want to explain why thiamine demands are increased in diabetes and to summarise data indicating thiamine mishandling in diabetics(by review of the studies mapping the prevalence and the degree ofthiamine deficiency in diabetics). Finally, we would like to summarise the evidence for the beneficial effect of thiamine supplementation in progression of hyperglycemia-related pathology and, therefore, to justify its importance in determining the harmful impact of hyperglycemia in diabetes. Based on the data presented it could be concluded that although experimental studies mostly resulted in beneficial effects, clinical studies of appropriate size and duration focusing on the effect of thiamine supplementation/therapy on hard endpoints are missing at present. Moreover, it is not currently clear which mechanisms contribute to the deficient action of thiamine in diabetes most. Experimental studies on the molecular mechanisms of thiamine deficiency in diabetes are critically needed before clear answer to diabetes community could be given.展开更多
The pathogenesis of neuroblastoma with bone or bone marrow metastasis (NB-BBM)and its complex immune microenvironment remain poorly elucidated, hampering the advancement of effective risk prediction for BBM and limiti...The pathogenesis of neuroblastoma with bone or bone marrow metastasis (NB-BBM)and its complex immune microenvironment remain poorly elucidated, hampering the advancement of effective risk prediction for BBM and limiting therapeutic strategies. Feature recognition of 142 paraffin-embedded hematoxylin-eosin-stained tumor section images was conductedusing a Swin-Transformer for pathological histology to predict NB-BBM occurrence. Single-celltranscriptomics identified a tumor cell subpopulation (NB3) and two tumor-associated macrophage (TAM) subpopulations (SPP1^(+) TAMs and IGHM^(+) TAMs) closely associated with BBM andhighlighted transketolase (TKT) as a key molecular marker for metastatic progression in NB.This extensive multi-omics investigation into NB-BBM enhances our understanding of single-celltranscriptional dynamics in NB beyond existing research, outlining the evolution from in situcarcinoma through tumorigenesis to bone marrow metastases. Furthermore, exploration ofthe immune microenvironment identified specific subpopulations of TAMs crucial in promotingNB-BBM, presenting new avenues for immunotherapy. These insights enhance our understanding of the metastatic process from NB to BBM and facilitate the development of more effectivediagnostic and therapeutic strategies for this aggressive pediatric cancer.展开更多
Anisomycin(compound 1),a multifunctional pyrrolidine antibiotic,primarily inhibits protein biosynthesis by binding to the ribosome.Upon binding to the ribosome,the para-phenol moiety of anisomycin inserts completely i...Anisomycin(compound 1),a multifunctional pyrrolidine antibiotic,primarily inhibits protein biosynthesis by binding to the ribosome.Upon binding to the ribosome,the para-phenol moiety of anisomycin inserts completely into the hydrophobic crevice of the A-site and blocks the access of the incoming aminoacyl-tRNAs,disrupting peptide bond formation.Hence,the para-methoxyphenyl group serves as a starting point for developing novel anisomycin analogs with potent antifungal and insecticidal properties.However,the activation and condensation mechanism of phenylpyruvic acid has not yet been elucidated.In this study,genetic manipulations of aniP and its homologue siAniP confirmed their indispensable role in 1 biosynthesis.Bioinformatics analysis suggested that AniP and siAniP function as transketolase.siAniP was found to catalyzed condensation between 4-hydroxyphe-nylpyruvic acid(3)and glyceraldehyde(GA),initiating pyrrolidine synthesis.siAniP was specific for aromatic keto acids and tolerant of aliphatic and aromatic aldehydes,and was able to catalyze the asymmetric intermo-lecular condensation of two keto acids,leading to the formation of 24α-hydroxy ketone.To the best of our knowledge,siAniP is the first TK that catalyzes the transfer of a C2 ketol and symmetrical intermolecular coupling using aromatic keto acids as donor substrates.Structural analysis,docking model construction,and site-directed mutagenesis identified that I220,H275,R322 and W391 were crucial for substrate binding.Moreover,sequence similarity network(SSN)-based genome neighborhood network(GNN)analyses of AniP suggested the widespread occurrence of the AniP-like-mediated reaction in the biosynthesis of 1 and its analogs,particularly in the assembly of benzylpyrrolidine.These findings not only expand the repertoire of TKs but also provide a potent biocatalyst that could be used for the structural innovation of 1 and its derivatives.展开更多
基金the National Natural Science Foundation of China (No. 30870871).
文摘Transketolase （TK）, a thiamine diphosphate （ThDP）-dependent enzyme, catalyzes several key reactions of nonoxidative branch of pentose phosphate pathway. TK is a homodimer with two active sites that locate at the interface between the contacting monomers. Both ThDP and bivalent cations are strictly needed for TK activation, just like that for all ThDPdependent enzymes. TK exists in all organisms that have been investigated. Up to now, one TK gene （TKT） and two transketolase-like genes （TKTL1 and TKTL2） have been identified in human genome. TKTL1 is reported to play a pivotal role in carcinogenesis and may have important implications in the nutrition and future treatment of patients with cancer. Research- ers have found TK variants and reduced activities of TK enzyme in patients with neurodegenerative diseases, diabetes, and cancer. Recent studies indicated TK as a novel role in the prevention and therapy of these diseases.
基金supported by a grant from Medical Scientific Research Foundation of Guangdong Province,China(No.A2018282).
文摘Objective:To determine whether B vitamin treatment was sufficient to reduce cognitive impairment associated with high-fat diets in rats and to modulate transketolase(TK)expression and activity.Methods:To test this,we separated 50 rats into five groups that were either fed a standard chow diet(controls)or a high-fat diet(experimental groups HO,HI,H2,and H3).HO group animals received no additional dietary supplementation,while H1 group animals were administered 100 mg/kg body weight(BW)thiamine,100 mg/kg BW riboflavin,and 250 mg/kg BW niacin each day,and group H2 animals received daily doses of 100 mg/kg BW pyridoxine,100 mg/kg BW cobalamin,and 5 mg/kg BW folate.Animals in the H3 group received the B vitamin regimens administered to both H1 and H2 each day.Results:Over time,group HO exhibited greater increases in BW and fat mass relative to other groups.When spatial and memory capabilities in these animals were evaluated via conditioned taste aversion(CTA)and Morris Water Maze(MWM),we found B vitamin treatment was associated with significant improvements relative to untreated HO controls.Similarly,B vitamin supplementation was associated with elevated TK expression in erythrocytes and hypothalamus of treated animals relative to those in HO(P<0.05).Conclusion:Together,these findings suggest B vitamin can modulate hypothalamic TK activity to reduce the severity of cognitive deficits in a rat model of obesity.As such,B vitamin supplementation may be a beneficial method for reducing cognitive dysfunction in clinical settings associated with high-fat diets.
文摘Transketolase, the most critical enzyme of the non-oxidative branch of the pentose phosphate pathway, has been reported as a novel target in Plasmodium falciparum as it has least homology with the human host. Homology model of P. falciparum transketolase (PfTk) was constructed using the crystal structure of S. cervisiae transketolase as a template, and used for the identification and prioritization of potential compounds targeted against Plasmodium falciparum transketolase. The docking studies with fructose-6-phosphate and thiamine pyrophosphate showed that His31, Asp473, Ser388, Arg361 and His465 formed hydrogen bonds with fructose-6-phosphate while pyrimidine ring of coenzyme interacted with conserved residues of protein viz., Leu121, Glu415, Gly119. The major interacting residues involved in binding of oxythiamine pyrophosphate were similar to cofactor binding site of PfTk. An integrated pharmacophore, co-factor ThDP and substrate fructose-6-pho- sphate, based virtual screening of a small mo- lecule database retrieved eight and thirteen compounds respectively. When screened for their activity against P. falciparum transketolase, one compound in case of ThDP and three compounds in case of fructose-6-phosphate based screening were found active against PfTk. Identification of these novel and chemically diverse inhibitors provides initial leads for optimization of more potent and efficacious drug candidates to treat malarial infection.
基金Supported by The Grant from the Ministry of Health of Czech Republic,No.NT13198
文摘Growing prevalence of diabetes(type 2 as well as type 1) and its related morbidity due to vascular complications creates a large burden on medical care worldwide. Understanding the molecular pathogenesis of chronic micro-, macro- and avascular complications mediated by hyperglycemia is of crucial importance since novel therapeutic targets can be identified and tested. Thiamine(vitamin B1) is an essential cofactor of several enzymes involved in carbohydrate metabolism and published data suggest that thiamine metabolism in diabetes is deficient. This review aims to point out the physiological role of thiamine in metabolism of glucose and amino acids, to present overview of thiamine metabolism and to describe the consequences of thiamine deficiency(either clinically manifest or latent). Furthermore, we want to explain why thiamine demands are increased in diabetes and to summarise data indicating thiamine mishandling in diabetics(by review of the studies mapping the prevalence and the degree ofthiamine deficiency in diabetics). Finally, we would like to summarise the evidence for the beneficial effect of thiamine supplementation in progression of hyperglycemia-related pathology and, therefore, to justify its importance in determining the harmful impact of hyperglycemia in diabetes. Based on the data presented it could be concluded that although experimental studies mostly resulted in beneficial effects, clinical studies of appropriate size and duration focusing on the effect of thiamine supplementation/therapy on hard endpoints are missing at present. Moreover, it is not currently clear which mechanisms contribute to the deficient action of thiamine in diabetes most. Experimental studies on the molecular mechanisms of thiamine deficiency in diabetes are critically needed before clear answer to diabetes community could be given.
基金supported in part by research grants from the Key Project of the National Key R&D Plan“Research on Prevention and Control of Major Chronic Non-Communicable Diseases”(China)the Ministry of Science and Technology of the People’s Republic of China,and the National Key R&D Program of China(No.2018YFC1313000,2018YFC1313004).
文摘The pathogenesis of neuroblastoma with bone or bone marrow metastasis (NB-BBM)and its complex immune microenvironment remain poorly elucidated, hampering the advancement of effective risk prediction for BBM and limiting therapeutic strategies. Feature recognition of 142 paraffin-embedded hematoxylin-eosin-stained tumor section images was conductedusing a Swin-Transformer for pathological histology to predict NB-BBM occurrence. Single-celltranscriptomics identified a tumor cell subpopulation (NB3) and two tumor-associated macrophage (TAM) subpopulations (SPP1^(+) TAMs and IGHM^(+) TAMs) closely associated with BBM andhighlighted transketolase (TKT) as a key molecular marker for metastatic progression in NB.This extensive multi-omics investigation into NB-BBM enhances our understanding of single-celltranscriptional dynamics in NB beyond existing research, outlining the evolution from in situcarcinoma through tumorigenesis to bone marrow metastases. Furthermore, exploration ofthe immune microenvironment identified specific subpopulations of TAMs crucial in promotingNB-BBM, presenting new avenues for immunotherapy. These insights enhance our understanding of the metastatic process from NB to BBM and facilitate the development of more effectivediagnostic and therapeutic strategies for this aggressive pediatric cancer.
基金supported by a grant from the National Key research and development Program of China(2021YFA0909500,2021 YFC2100100,2021YFC2100600)National Natural Science Foundation of China(32170077,32170075).
文摘Anisomycin(compound 1),a multifunctional pyrrolidine antibiotic,primarily inhibits protein biosynthesis by binding to the ribosome.Upon binding to the ribosome,the para-phenol moiety of anisomycin inserts completely into the hydrophobic crevice of the A-site and blocks the access of the incoming aminoacyl-tRNAs,disrupting peptide bond formation.Hence,the para-methoxyphenyl group serves as a starting point for developing novel anisomycin analogs with potent antifungal and insecticidal properties.However,the activation and condensation mechanism of phenylpyruvic acid has not yet been elucidated.In this study,genetic manipulations of aniP and its homologue siAniP confirmed their indispensable role in 1 biosynthesis.Bioinformatics analysis suggested that AniP and siAniP function as transketolase.siAniP was found to catalyzed condensation between 4-hydroxyphe-nylpyruvic acid(3)and glyceraldehyde(GA),initiating pyrrolidine synthesis.siAniP was specific for aromatic keto acids and tolerant of aliphatic and aromatic aldehydes,and was able to catalyze the asymmetric intermo-lecular condensation of two keto acids,leading to the formation of 24α-hydroxy ketone.To the best of our knowledge,siAniP is the first TK that catalyzes the transfer of a C2 ketol and symmetrical intermolecular coupling using aromatic keto acids as donor substrates.Structural analysis,docking model construction,and site-directed mutagenesis identified that I220,H275,R322 and W391 were crucial for substrate binding.Moreover,sequence similarity network(SSN)-based genome neighborhood network(GNN)analyses of AniP suggested the widespread occurrence of the AniP-like-mediated reaction in the biosynthesis of 1 and its analogs,particularly in the assembly of benzylpyrrolidine.These findings not only expand the repertoire of TKs but also provide a potent biocatalyst that could be used for the structural innovation of 1 and its derivatives.
