Cation Binding and Thermostability of FTHFS Monovalent Cation Binding Sites and Thermostability ofN10-Formyltetrahydrofolate Synthetase fromMoorella thermoacetica†,‡

Biochemistry ◽  
2000 ◽  
Vol 39 (47) ◽  
pp. 14481-14486 ◽  
Author(s):  
Ramin Radfar ◽  
Adam Leaphart ◽  
John M. Brewer ◽  
Wladek Minor ◽  
Jerome D. Odom ◽  
...  
Keyword(s):  
Binding Sites ◽  
Monovalent Cation ◽  
Cation Binding ◽  
Formyltetrahydrofolate Synthetase

scholarly journals The role of monovalent cations in the ATPase reaction of DNA gyrase

2015 ◽  
Vol 71 (4) ◽  
pp. 996-1005 ◽  
Author(s):  
Stephen James Hearnshaw ◽  
Terence Tsz-Hong Chung ◽  
Clare Elizabeth Mary Stevenson ◽  
Anthony Maxwell ◽  
David Mark Lawson
Keyword(s):  
Escherichia Coli ◽  
Binding Sites ◽  
Dna Gyrase ◽  
Monovalent Cation ◽  
Cation Binding ◽  
Monovalent Cations ◽  
Atpase Domain ◽  
Atpase Reaction ◽  
Resolution Structure

Four new crystal structures of the ATPase domain of the GyrB subunit ofEscherichia coliDNA gyrase have been determined. One of these, solved in the presence of K+, is the highest resolution structure reported so far for this domain and, in conjunction with the three other structures, reveals new insights into the function of this domain. Evidence is provided for the existence of two monovalent cation-binding sites: site 1, which preferentially binds a K+ion that interacts directly with the α-phosphate of ATP, and site 2, which preferentially binds an Na+ion and the functional significance of which is not clear. The crystallographic data are corroborated by ATPase data, and the structures are compared with those of homologues to investigate the broader conservation of these sites.

scholarly journals Divalent cation competition with [3H]saxitoxin binding to tetrodotoxin-resistant and -sensitive sodium channels. A two-site structural model of ion/toxin interaction.

1993 ◽  
Vol 101 (2) ◽  
pp. 153-182 ◽  
Author(s):  
D D Doyle ◽  
Y Guo ◽  
S L Lustig ◽  
J Satin ◽  
R B Rogart ◽  
...  
Keyword(s):  
Divalent Cation ◽  
Binding Sites ◽  
Structural Model ◽  
Divalent Cations ◽  
Ph Dependence ◽  
Monovalent Cation ◽  
Cation Binding ◽  
Na Channel ◽  
Na Channels ◽  
Ph Titration

Monovalent and divalent cations competitively displace tetrodotoxin and saxitoxin (STX) from their binding sites on nerve and skeletal muscle Na channels. Recent studies of cloned cardiac (toxin-resistant) and brain (toxin-sensitive) Na channels suggest important structural differences in their toxin and divalent cation binding sites. We used a partially purified preparation of sheep cardiac Na channels to compare monovalent and divalent cation competition and pH dependence of binding of [3H]STX between these toxin-resistant channels and toxin-sensitive channels in membranes prepared from rat brain. The effects of several chemical modifiers of amino acid groups were also compared. Toxin competition curves for Na+ in heart and Cd2+ in brain yielded similar KD values to measurements of equilibrium binding curves. The monovalent cation sequence for effectiveness of [3H]STX competition is the same for cardiac and brain Na channels, with similar KI values for each ion and slopes of -1. The effectiveness sequence corresponds to unhydrated ion radii. For seven divalent cations tested (Ca2+, Mg2+, Mn2+, Co2+, Ni2+, Cd2+, and Zn2+) the sequence for [3H]STX competition was also similar. However, whereas all ions displaced [3H]STX from cardiac Na channels at lower concentrations, Cd2+ and Zn2+ did so at much lower concentrations. In addition, and by way of explication, the divalent ion competition curves for both brain and cardiac channels (except for Cd2+ and Zn2+ in heart and Zn2+ in brain) had slopes of less than -1, consistent with more than one interaction site. Two-site curves had statistically better fits than one-site curves. The derived values of KI for the higher affinity sites were similar between the channel types, but the lower affinity KI's were larger for heart. On the other hand, the slopes of competition curves for Cd2+ and Zn2+ were close to -1, as if the cardiac Na channel had one dominant site of interaction or more than one site with similar values for KI. pH titration of [3H]STX binding to cardiac channels showed a pKa of 5.5 and a slope of 0.6-0.9, compared with a pKa of 5.1 and slope of 1 for brain channels. Tetramethyloxonium (TMO) treatment abolished [3H]STX binding to cardiac and brain channels and STX protected channels, but the TMO effect was less dramatic for cardiac channels. Trinitrobenzene sulfonate preferentially abolished [3H]STX binding to brain channels by action at an STX protected site.(ABSTRACT TRUNCATED AT 400 WORDS)

Potential monovalent cation-binding sites in aldehyde dehydrogenases

2013 ◽  
Vol 202 (1-3) ◽  
pp. 41-50 ◽  
Author(s):  
Lilian González-Segura ◽  
Héctor Riveros-Rosas ◽  
Ángel G. Díaz-Sánchez ◽  
Adriana Julián-Sánchez ◽  
Rosario A. Muñoz-Clares
Keyword(s):  
Binding Sites ◽  
Monovalent Cation ◽  
Cation Binding ◽  
Aldehyde Dehydrogenases

scholarly journals First Characterization of an Archaeal GTP-Dependent Phosphoenolpyruvate Carboxykinase from the Hyperthermophilic Archaeon Thermococcus kodakaraensis KOD1

2004 ◽  
Vol 186 (14) ◽  
pp. 4620-4627 ◽  
Author(s):  
Wakao Fukuda ◽  
Toshiaki Fukui ◽  
Haruyuki Atomi ◽  
Tadayuki Imanaka
Keyword(s):  
Binding Sites ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Cation Binding ◽  
Activity Levels ◽  
Binding Region ◽  
Hyperthermophilic Archaeon ◽  
Dependent Activity ◽  
Additional Role

ABSTRACT Phosphoenolpyruvate carboxykinase (PCK), which catalyzes the nucleotide-dependent, reversible decarboxylation of oxaloacetate to yield phosphoenolpyruvate and CO2, is one of the important enzymes in the interconversion between C3 and C4 metabolites. This study focused on the first characterization of the enzymatic properties and expression profile of an archaeal PCK from the hyperthermophilic archaeon Thermococcus kodakaraensis (Pck Tk ). Pck Tk showed 30 to 35% identities to GTP-dependent PCKs from mammals and bacteria but was located in a branch distinct from that of the classical enzymes in the phylogenetic tree, together with other archaeal homologs from Pyrococcus and Sulfolobus spp. Several catalytically important regions and residues, found in all known PCKs irrespective of their nucleotide specificities, were conserved in Pck Tk . However, the predicted GTP-binding region was unique compared to those in other GTP-dependent PCKs. The recombinant Pck Tk actually exhibited GTP-dependent activity and was suggested to possess dual cation-binding sites specific for Mn2+ and Mg2+. The enzyme preferred phosphoenolpyruvate formation from oxaloacetate, since the Km value for oxaloacetate was much lower than that for phosphoenolpyruvate. The transcription and activity levels in T. kodakaraensis were higher under gluconeogenic conditions than under glycolytic conditions. These results agreed with the role of Pck Tk in providing phosphoenolpyruvate from oxaloacetate as the first step of gluconeogenesis in this hyperthermophilic archaeon. Additionally, under gluconeogenic conditions, we observed higher expression levels of Pck Tk on pyruvate than on amino acids, implying that it plays an additional role in the recycling of excess phosphoenolpyruvate produced from pyruvate, replacing the function of the anaplerotic phosphoenolpyruvate carboxylase that is missing from this archaeon.

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