Molecular function of the prolyl cis/trans isomerase and metallochaperone SlyD

2013 ◽  
Vol 394 (8) ◽  
pp. 965-975 ◽  
Author(s):  
Michael Kovermann ◽  
Franz X. Schmid ◽  
Jochen Balbach
Keyword(s):  
Molecular Chaperone ◽  
Molecular Basis ◽  
Catalytic Efficiency ◽  
Enzyme Mechanism ◽  
Molecular Function ◽  
Twin Arginine Translocation ◽  
Chaperone Function ◽  
Nickel Binding ◽  
Biophysical Analysis ◽  
Optimal Function

Abstract SlyD is a bacterial two-domain protein that functions as a molecular chaperone, a prolyl cis/trans isomerase, and a nickel-binding protein. This review summarizes recent findings about the molecular enzyme mechanism of SlyD. The chaperone function located in one domain of SlyD is involved in twin-arginine translocation and increases the catalytic efficiency of the prolyl cis/trans isomerase domain in protein folding by two orders of magnitude. The C-terminal tail of SlyD binds Ni2+ ions and supplies them for the maturation of [NiFe] hydrogenases. A combined biochemical and biophysical analysis revealed the molecular basis of the delicate interplay of the different domains of SlyD for optimal function.

scholarly journals Thermotolerance and molecular chaperone function of an SGT1-like protein from the psychrophilic yeast, Glaciozyma antarctica

2016 ◽  
Vol 21 (4) ◽  
pp. 707-715 ◽  
Author(s):  
Nur Athirah Yusof ◽  
Noor Haza Fazlin Hashim ◽  
Travis Beddoe ◽  
Nor Muhammad Mahadi ◽  
Rosli Md Illias ◽  
...  
Keyword(s):  
Molecular Chaperone ◽  
Chaperone Function ◽  
Psychrophilic Yeast

scholarly journals AMP-forming acetyl-CoA synthetases in Archaea show unexpected diversity in substrate utilization

Archaea ◽  
2006 ◽  
Vol 2 (2) ◽  
pp. 95-107 ◽  
Author(s):  
Cheryl Ingram-Smith ◽  
Kerry S. Smith
Keyword(s):  
Phylogenetic Analysis ◽  
Molecular Basis ◽  
Catalytic Efficiency ◽  
Adenosine Monophosphate ◽  
Archaeoglobus Fulgidus ◽  
Acetyl Coa ◽  
Chain Acyl ◽  
Key Enzyme ◽  
Methanothermobacter Thermautotrophicus ◽  
Branched Chain

Adenosine monophosphate (AMP)-forming acetyl-CoA synthetase (ACS; acetate:CoA ligase (AMP-forming), EC 6.2.1.1) is a key enzyme for conversion of acetate to acetyl-CoA, an essential intermediate at the junction of anabolic and catabolic pathways. Phylogenetic analysis of putative short and medium chain acyl-CoA synthetase sequences indicates that the ACSs form a distinct clade from other acyl-CoA synthetases. Within this clade, the archaeal ACSs are not monophyletic and fall into three groups composed of both bacterial and archaeal sequences. Kinetic analysis of two archaeal enzymes, an ACS fromMethanothermobacter thermautotrophicus(designated as MT-ACS1) and an ACS fromArchaeoglobus fulgidus(designated as AF-ACS2), revealed that these enzymes have very different properties. MT-ACS1 has nearly 11-fold higher affinity and 14-fold higher catalytic efficiency with acetate than with propionate, a property shared by most ACSs. However, AF-ACS2 has only 2.3-fold higher affinity and catalytic efficiency with acetate than with propionate. This enzyme has an affinity for propionate that is almost identical to that of MT-ACS1 for acetate and nearly tenfold higher than the affinity of MT-ACS1 for propionate. Furthermore, MT-ACS1 is limited to acetate and propionate as acyl substrates, whereas AF-ACS2 can also utilize longer straight and branched chain acyl substrates. Phylogenetic analysis, sequence alignment and structural modeling suggest a molecular basis for the altered substrate preference and expanded substrate range of AF-ACS2 versus MT-ACS1.

scholarly journals Enzyme activity after resealing within ghost erythrocyte cells, and protection by α-crystallin against fructose-induced inactivation

2002 ◽  
Vol 368 (3) ◽  
pp. 865-874 ◽  
Author(s):  
Barry K. DERHAM ◽  
John J. HARDING
Keyword(s):  
Enzyme Activity ◽  
Molecular Chaperone ◽  
Soluble Fraction ◽  
Erythrocyte Ghosts ◽  
Ghost Cell ◽  
Chaperone Function ◽  
Zero Time ◽  
Soluble Fractions

The role of α-crystallin as a molecular chaperone has been shown in many in vitro studies. In the present paper, we report on the chaperone function of α-crystallin within resealed erythrocyte ghosts. Eight enzymes were individually resealed within erythrocyte ghosts and assayed at zero time and at 24h. The ghost cell suspension was separated into soluble and membrane fractions. Five of the enzymes had significantly greater enzyme activity after 24h than the control within the soluble fractions. Fructation caused a decrease in enzyme activity (relative to the control). Resealing of α-crystallin within the ghost cell alongside the enzymes protected against inactivation by fructose within the soluble fraction.

scholarly journals Molecular Basis for Ser/Thr Specificity in PKA Signaling

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1548 ◽  
Author(s):  
Matthias J. Knape ◽  
Maximilian Wallbott ◽  
Nicole C. G. Burghardt ◽  
Daniela Bertinetti ◽  
Jan Hornung ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Substrate Specificity ◽  
Metal Ions ◽  
Protein Kinases ◽  
Molecular Basis ◽  
Kinase Inhibitor ◽  
Adenine Nucleotides ◽  
Catalytic Efficiency ◽  
Specific Protein ◽  
Divalent Metal Ions

cAMP-dependent protein kinase (PKA) is the major receptor of the second messenger cAMP and a prototype for Ser/Thr-specific protein kinases. Although PKA strongly prefers serine over threonine substrates, little is known about the molecular basis of this substrate specificity. We employ classical enzyme kinetics and a surface plasmon resonance (SPR)-based method to analyze each step of the kinase reaction. In the absence of divalent metal ions and nucleotides, PKA binds serine (PKS) and threonine (PKT) substrates, derived from the heat-stable protein kinase inhibitor (PKI), with similar affinities. However, in the presence of metal ions and adenine nucleotides, the Michaelis complex for PKT is unstable. PKA phosphorylates PKT with a higher turnover due to a faster dissociation of the product complex. Thus, threonine substrates are not necessarily poor substrates of PKA. Mutation of the DFG+1 phenylalanine to β-branched amino acids increases the catalytic efficiency of PKA for a threonine peptide substrate up to 200-fold. The PKA Cα mutant F187V forms a stable Michaelis complex with PKT and shows no preference for serine versus threonine substrates. Disease-associated mutations of the DFG+1 position in other protein kinases underline the importance of substrate specificity for keeping signaling pathways segregated and precisely regulated.

scholarly journals Exploring Novel Functions of the Small GTPase Ypt1p under Heat-Shock by Characterizing a Temperature-Sensitive Mutant Yeast Strain, ypt1-G80D

2019 ◽  
Vol 20 (1) ◽  
pp. 132 ◽  
Author(s):  
Chang Ho Kang ◽  
Joung Hun Park ◽  
Eun Seon Lee ◽  
Seol Ki Paeng ◽  
Ho Byoung Chae ◽  
...  
Keyword(s):  
Heat Stress ◽  
Heat Shock ◽  
Molecular Chaperone ◽  
Stress Sensitivity ◽  
Small Gtpase ◽  
Stress Conditions ◽  
Temperature Sensitive ◽  
Heat Sensitivity ◽  
Chemical Chaperone ◽  
Chaperone Function

In our previous study, we found that Ypt1p, a Rab family small GTPase protein, exhibits a stress-driven structural and functional switch from a GTPase to a molecular chaperone, and mediates thermo tolerance in Saccharomyces cerevisiae. In the current study, we focused on the temperature-sensitive ypt1-G80D mutant, and found that the mutant cells are highly sensitive to heat-shock, due to a deficiency in the chaperone function of Ypt1pG80D. This defect results from an inability of the protein to form high molecular weight polymers, even though it retains almost normal GTPase function. The heat-stress sensitivity of ypt1-G80D cells was partially recovered by treatment with 4-phenylbutyric acid, a chemical chaperone. These findings indicate that loss of the chaperone function of Ypt1pG80D underlies the heat sensitivity of ypt1-G80D cells. We also compared the proteomes of YPT1 (wild-type) and ypt1-G80D cells to investigate Ypt1p-controlled proteins under heat-stress conditions. Our findings suggest that Ypt1p controls an abundance of proteins involved in metabolism, protein synthesis, cellular energy generation, stress response, and DNA regulation. Finally, we suggest that Ypt1p essentially regulates fundamental cellular processes under heat-stress conditions by acting as a molecular chaperone.

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