Crystal structure of trypanosoma cruzi tyrosine aminotransferase: Substrate specificity is influenced by cofactor binding mode

Paraburkholderia xenovorans degrades organic wastes, including polychlorinated biphenyls. The atomic structure of a putative dehydrogenase/reductase (SDR) from P. xenovorans (PxSDR) was determined in space group P21 at a resolution of 1.45 Å. PxSDR shares less than 37% sequence identity with any known structure and assembles as a prototypical SDR tetramer. As expected, there is some conformational flexibility and difference in the substrate-binding cavity, which explains the substrate specificity. Uniquely, the cofactor-binding cavity of PxSDR is not well conserved and differs from those of other SDRs. PxSDR has an additional seven amino acids that form an additional unique loop within the cofactor-binding cavity. Further studies are required to determine how these differences affect the enzymatic functions of the SDR.

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Recombinant tyrosine aminotransferase from Trypanosoma cruzi: structural characterization and site directed mutagenesis of a broad substrate specificity enzyme

Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology ◽

10.1016/s0167-4838(01)00136-4 ◽

2001 ◽

Vol 1546 (2) ◽

pp. 268-281 ◽

Cited By ~ 20

Author(s):

Cristina Nowicki ◽

Giselle Reynoso Hunter ◽

Marisa Montemartini-Kalisz ◽

Wulf Blankenfeldt ◽

Hans-Jürgen Hecht ◽

...

Keyword(s):

Trypanosoma Cruzi ◽

Substrate Specificity ◽

Structural Characterization ◽

Tyrosine Aminotransferase ◽

Site Directed Mutagenesis ◽

Directed Mutagenesis ◽

Broad Substrate Specificity

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Ruthenium(II) Complexes Bearing Thioether-Appended α- Iminopyridine Ligands: Arene Precursors Permit Access to K2-N,N and K3-N,N,S Complexes

10.26434/chemrxiv.9693506.v1 ◽

2019 ◽

Author(s):

Victoria A. Ternes ◽

Hannah A. Morgan ◽

Austin P. Lanquist ◽

Michael P. Murray ◽

Bradley Wile

Keyword(s):

Crystal Structure ◽

Solid State ◽

Strong Field ◽

Active Role ◽

Binding Mode ◽

Phenethyl Alcohol ◽

Ru Complexes

Herein we report the preparation of a series of Ru(II) complexes featuring alpha-iminopyridine ligands bearing thioether functionality (NNSR, where R = Me, CH2Ph, Ph). Metallation using (p cymene)RuCl dimer permits access to (k2-N,N)Ru complexes in which the thioether moiety remains uncoordinated. In the presence of a strong field ligand such as acetonitrile or triphenylphosphine, the p-cymene moiety is displaced, and the ligand adopts a k3-N,N,S binding mode. These complexes are characterized using a combination of solution and solid state methods, including the crystal structure of [(NNSMe)Ru(NCMe)2Cl]Cl. The k2-N,N Ru(II) complexes are shown to serve as efficient precatalysts for the oxidation of sec-phenethyl alcohol at 5 mol% loadings, using a variety of external oxidants and solvents. The complex bearing an S-Ph donor was found to be the most active of those surveyed, suggesting that the thioether donor plays an active role in catalyst speciation for this transformation.

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Crystal structures of Ca2+–calmodulin bound to NaV C-terminal regions suggest role for EF-hand domain in binding and inactivation

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1818618116 ◽

2019 ◽

Vol 116 (22) ◽

pp. 10763-10772 ◽

Cited By ~ 10

Author(s):

Bernd R. Gardill ◽

Ricardo E. Rivera-Acevedo ◽

Ching-Chieh Tung ◽

Filip Van Petegem

Keyword(s):

Crystal Structure ◽

Binding Sites ◽

Binding Mode ◽

Conformational Switch ◽

Channel Inactivation ◽

Dependent Inactivation ◽

Ef Hand ◽

Inherited Arrhythmia ◽

A Site

Voltage-gated sodium (NaV) and calcium channels (CaV) form targets for calmodulin (CaM), which affects channel inactivation properties. A major interaction site for CaM resides in the C-terminal (CT) region, consisting of an IQ domain downstream of an EF-hand domain. We present a crystal structure of fully Ca2+-occupied CaM, bound to the CT of NaV1.5. The structure shows that the C-terminal lobe binds to a site ∼90° rotated relative to a previous site reported for an apoCaM complex with the NaV1.5 CT and for ternary complexes containing fibroblast growth factor homologous factors (FHF). We show that the binding of FHFs forces the EF-hand domain in a conformation that does not allow binding of the Ca2+-occupied C-lobe of CaM. These observations highlight the central role of the EF-hand domain in modulating the binding mode of CaM. The binding sites for Ca2+-free and Ca2+-occupied CaM contain targets for mutations linked to long-QT syndrome, a type of inherited arrhythmia. The related NaV1.4 channel has been shown to undergo Ca2+-dependent inactivation (CDI) akin to CaVs. We present a crystal structure of Ca2+/CaM bound to the NaV1.4 IQ domain, which shows a binding mode that would clash with the EF-hand domain. We postulate the relative reorientation of the EF-hand domain and the IQ domain as a possible conformational switch that underlies CDI.

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