Schröder-Tittmann, Kathrin

[["dc.bibliographiccitation.artnumber","e48321"],["dc.bibliographiccitation.issue","10"],["dc.bibliographiccitation.journal","PLoS ONE"],["dc.bibliographiccitation.volume","7"],["dc.contributor.author","Schneider, Stefan"],["dc.contributor.author","Luedtke, Stefan"],["dc.contributor.author","Schroeder-Tittmann, Kathrin"],["dc.contributor.author","Wechsler, Cindy"],["dc.contributor.author","Meyer, Danilo"],["dc.contributor.author","Tittmann, Kai"],["dc.date.accessioned","2018-11-07T09:04:23Z"],["dc.date.available","2018-11-07T09:04:23Z"],["dc.date.issued","2012"],["dc.description.abstract","Besides transketolase (TKT), a thiamin-dependent enzyme of the pentose phosphate pathway, the human genome encodes for two closely related transketolase-like proteins, which share a high sequence identity with TKT. Transketolase-like protein 1 (TKTL1) has been implicated in cancerogenesis as its cellular expression levels were reported to directly correlate with invasion efficiency of cancer cells and patient mortality. It has been proposed that TKTL1 exerts its function by catalyzing an unusual enzymatic reaction, a hypothesis that has been the subject of recent controversy. The most striking difference between TKTL1 and TKT is a deletion of 38 consecutive amino acids in the N-terminal domain of the former, which constitute part of the active site in authentic TKT. Our structural and sequence analysis suggested that TKTL1 might not possess transketolase activity. In order to test this hypothesis in the absence of a recombinant expression system for TKTL1 and resilient data on its biochemical properties, we have engineered and biochemically characterized a \"pseudo-TKTL1\" Delta 38 deletion variant of human TKT (TKT Delta 38) as a viable model of TKTL1. Although the isolated protein is properly folded under in vitro conditions, both thermal stability as well as stability of the TKT-specific homodimeric assembly are markedly reduced. Circular dichroism and NMR spectroscopic analysis further indicates that TKT Delta 38 is unable to bind the thiamin cofactor in a specific manner, even at superphysiological concentrations. No transketolase activity of TKT Delta 38 can be detected for conversion of physiological sugar substrates thus arguing against an intrinsically encoded enzymatic function of TKTL1 in tumor cell metabolism."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft [FOR 1296]"],["dc.identifier.doi","10.1371/journal.pone.0048321"],["dc.identifier.isi","000310600500103"],["dc.identifier.pmid","23118983"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/8322"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/25106"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Public Library Science"],["dc.relation.issn","1932-6203"],["dc.rights","CC BY 2.5"],["dc.rights.uri","https://creativecommons.org/licenses/by/2.5"],["dc.title","A Delta 38 Deletion Variant of Human Transketolase as a Model of Transketolase-Like Protein 1 Exhibits No Enzymatic Activity"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","31559"],["dc.bibliographiccitation.issue","41"],["dc.bibliographiccitation.journal","Journal of Biological Chemistry"],["dc.bibliographiccitation.lastpage","31570"],["dc.bibliographiccitation.volume","285"],["dc.contributor.author","Mitschke, Lars"],["dc.contributor.author","Parthier, Christoph"],["dc.contributor.author","Schroeder-Tittmann, Kathrin"],["dc.contributor.author","Coy, Johannes"],["dc.contributor.author","Luedtke, Stefan"],["dc.contributor.author","Tittmann, Kai"],["dc.date.accessioned","2018-11-07T08:38:05Z"],["dc.date.available","2018-11-07T08:38:05Z"],["dc.date.issued","2010"],["dc.description.abstract","The crystal structure of human transketolase (TKT), a thiamine diphosphate (ThDP) and Ca(2+)-dependent enzyme that catalyzes the interketol transfer between ketoses and aldoses as part of the pentose phosphate pathway, has been determined to 1.75 angstrom resolution. The recombinantly produced protein crystallized in space group C2 containing one monomer in the asymmetric unit. Two monomers form the homodimeric biological assembly with two identical active sites at the dimer interface. Although the protomer exhibits the typical three (alpha/beta)-domain structure and topology reported for TKTs from other species, structural differences are observed for several loop regions and the linker that connects the PP and Pyr domain. The cofactor and substrate binding sites of human TKT bear high resemblance to those of other TKTs but also feature unique properties, including two lysines and a serine that interact with the beta-phosphate of ThDP. Furthermore, Gln(189) spans over the thiazolium moiety of ThDP and replaces an isoleucine found in most non-mammalian TKTs. The side chain of Gln(428) forms a hydrogen bond with the 4'-amino group of ThDP and replaces a histidine that is invariant in all non-mammalian TKTs. All other amino acids involved in substrate binding and catalysis are strictly conserved. Besides a steady-state kinetic analysis, microscopic equilibria of the donor half-reaction were characterized by an NMR-based intermediate analysis. These studies reveal that formation of the central 1,2-dihydroxyethyl-ThDP carbanion-enamine intermediate is thermodynamically favored with increasing carbon chain length of the donor ketose substrate. Based on the structure of human transketolase and sequence alignments, putative functional properties of the related transketolase-like proteins TKTL1 and -2 are discussed in light of recent findings suggesting that TKTL1 plays a role in cancerogenesis."],["dc.description.sponsorship","Fonds der Chemischen Industrie; Deutsche Forschungsgemeinschaft"],["dc.identifier.doi","10.1074/jbc.M110.149955"],["dc.identifier.isi","000282764600050"],["dc.identifier.pmid","20667822"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/18689"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Soc Biochemistry Molecular Biology Inc"],["dc.relation.issn","0021-9258"],["dc.title","The Crystal Structure of Human Transketolase and New Insights into Its Mode of Action"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]