Structural highlights
Function[KTRC_SCHMA] This family of enzymes reversibly catalyzes the transfer of phosphate between ATP and various phosphogens (e.g. creatine phosphate).[1] Publication Abstract from PubMedThe taurocyamine kinase from the blood fluke Schistosoma mansoni (SmTK) belongs to the phosphagen kinase (PK) family and catalyzes the reversible Mg2+-dependent transfer of a phosphoryl group between ATP and taurocyamine. SmTK is derived from gene duplication, as are all known trematode TKs. Our crystallographic study of SmTK reveals the first atomic structure of both a TK and a PK with a bilobal structure. The two unliganded lobes present a canonical open conformation and interact via their respective C- and N-terminal domains at a helix-mediated interface. This spatial arrangement differs from that observed in true dimeric PKs, in which both N-terminal domains make contact. Our structures of SmTK complexed with taurocyamine or L-arginine compounds explain the mechanism by which an arginine residue of the phosphagen-specificity loop is crucial for substrate specificity. An SmTK crystal was soaked with the dead-end transition-state analog (TSA) components taurocyamine-NO32--MgADP. One SmTK monomer was observed with two bound TSAs and an asymmetric conformation, with the first lobe semi-closed and the second closed. However, isothermal titration calorimetry and enzyme kinetics experiments showed that the two lobes function independently. A small-angle X-ray scattering model of SmTK-TSA in solution with two closed active sites was generated. The substrate -free and -bound crystal structures of the duplicated taurocyamine kinase from the human parasite Schistosoma mansoni.,Merceron R, Awama AM, Montserret R, Marcillat O, Gouet P J Biol Chem. 2015 Apr 2. pii: jbc.M114.628909. PMID:25837252[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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