scholarly journals Identification of C-terminal motifs responsible for transmission of inhibition by ATP of mammalian phosphofructokinase, and their contribution to other allosteric effects

2004 ◽  
Vol 377 (1) ◽  
pp. 77-84 ◽  
Author(s):  
Oscar H. MARTÍNEZ-COSTA ◽  
Carmen HERMIDA ◽  
Cristina SÁNCHEZ-MARTÍNEZ ◽  
Belén SANTAMARÍA ◽  
Juan J. ARAGÓN
Keyword(s):  
Point Mutations ◽  
Terminal Part ◽  
Protein Fluorescence ◽  
Binding Studies ◽  
C Terminus ◽  
Allosteric Effectors ◽  
Inhibitory Site ◽  
Intrinsic Protein Fluorescence ◽  
Strong Activator

Systematic deletions and point mutations in the C-terminal extension of mammalian PFK (phosphofructokinase) led us to identify Leu-767 and Glu-768 of the M-type isoform (PFK-M) as the motifs responsible for the role of this region in inhibition by MgATP. These amino acids are the only residues of the C-terminus that are conserved in all mammalian isoforms, and were found to have a similar function in the C-type isoenzyme. Both residues in PFK-C and Leu-767 in PFK-M were also observed to be critical for inhibition by citrate, which is synergistic with that by MgATP. Binding studies utilizing titration of intrinsic protein fluorescence indicated that the C-terminal part of the enzyme participates in the signal transduction route from the MgATP inhibitory site to the catalytic site, but does not contribute to the binding of this inhibitor, whereas it is essential for the binding of citrate. Mutations of the identified structural motifs did not alter either the action of other allosteric effectors that also interact with MgATP, such as the inhibitor phosphoenolpyruvate and the strong activator fructose 2,6-bisphosphate, or the co-operative effect of fructose 6-phosphate. The latter data provide evidence that activation by fructose 2,6-bisphosphate and fructose 6-phosphate co-operativity are not linked to the same allosteric transition as that mediating inhibition by MgATP.

scholarly journals C-terminal interactions mediate the quaternary dynamics of αB-crystallin

2013 ◽  
Vol 368 (1617) ◽  
pp. 20110405 ◽  
Author(s):  
Gillian R. Hilton ◽  
Georg K. A. Hochberg ◽  
Arthur Laganowsky ◽  
Scott I. McGinnigle ◽  
Andrew J. Baldwin ◽  
...  
Keyword(s):  
Self Assembly ◽  
Point Mutations ◽  
Small Heat Shock Protein ◽  
Core Domain ◽  
Subunit Exchange ◽  
Allosteric Communication ◽  
C Terminus ◽  
Energy Compensation ◽  
Αb Crystallin

αB-crystallin is a highly dynamic, polydisperse small heat-shock protein that can form oligomers ranging in mass from 200 to 800 kDa. Here we use a multifaceted mass spectrometry approach to assess the role of the C-terminal tail in the self-assembly of αB-crystallin. Titration experiments allow us to monitor the binding of peptides representing the C-terminus to the αB-crystallin core domain, and observe individual affinities to both monomeric and dimeric forms. Notably, we find that binding the second peptide equivalent to the core domain dimer is considerably more difficult than the first, suggesting a role of the C-terminus in regulating assembly. This finding motivates us to examine the effect of point mutations in the C-terminus in the full-length protein, by quantifying the changes in oligomeric distribution and corresponding subunit exchange rates. Our results combine to demonstrate that alterations in the C-terminal tail have a significant impact on the thermodynamics and kinetics of αB-crystallin. Remarkably, we find that there is energy compensation between the inter- and intra-dimer interfaces: when one interaction is weakened, the other is strengthened. This allosteric communication between binding sites on αB-crystallin is likely important for its role in binding target proteins.

Cytokine-induced inside-out activation of FcαR (CD89) is mediated by a single serine residue (S263) in the intracellular domain of the receptor

Blood ◽  
2001 ◽  
Vol 97 (11) ◽  
pp. 3478-3483 ◽  
Author(s):  
Madelon Bracke ◽  
Jan-Willem J. Lammers ◽  
Paul J. Coffer ◽  
Leo Koenderman
Keyword(s):  
Fc Receptors ◽  
Serine Residue ◽  
Binding Studies ◽  
Intracellular Domain ◽  
C Terminus ◽  
Endogenous Proteins ◽  
Cytokine Stimulation ◽  
Induced Signal ◽  
Inside Out

Fc receptors play an important role in leukocyte activation and the modulation of ligand binding (“activation”) is a critical point of regulation. Previous studies demonstrated that the Fc receptor for IgA (FcαRI/CD89) is regulated by cytokine stimulation, switching it to a high-binding state. To investigate the mechanism by which cytokine-induced signal transduction pathways result in FcαRI activation, cell lines expressing various receptor mutants were generated. Binding studies indicated that truncation of the C-terminus of the FcαRI resulted in constitutive IgA binding, removing the need for cytokine stimulation. Furthermore, mutagenesis of a single C-terminal serine residue (S263) to alanine (S>A) (single-letter amino acid codes) also resulted in constitutive IgA binding, whereas a serine to aspartate (S>D) mutation was no longer functional. The role of S263 might be in regulating the interaction with the cytoskeleton, because disruption of the cytoskeleton results in reduced IgA binding to both FcαRwt and FcαR_S>A. In addition, overexpression of a membrane-targeted intracellular domain of FcαR, and the introduction of cell-permeable CD89 fusion proteins blocked IgA binding, implying a competition for endogenous proteins. The proposal is made that Fc receptors are activated by cytokines via an inside-out mechanism converging at the cytoplasmic tail of these receptors.

scholarly journals Agrobacterium-Mediated T-DNA Transfer and Integration by Minimal VirD2 Consisting of the Relaxase Domain and a Type IV Secretion System Translocation Signal

2009 ◽  
Vol 22 (11) ◽  
pp. 1356-1365 ◽  
Author(s):  
Maartje van Kregten ◽  
Beatrice I. Lindhout ◽  
Paul J. J. Hooykaas ◽  
Bert J. van der Zaal
Keyword(s):  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Terminal Part ◽  
Type Iv ◽  
C Terminus ◽  
Localization Signal ◽  
Translocation Domain ◽  
First Time

The VirD2 protein of Agrobacterium tumefaciens is essential for processing and transport of the T-DNA. It has at least three functional domains: a relaxase domain at the N terminus, a bipartite nuclear localization signal (NLS), and a sequence called ω at the C terminus. We confirm here that deletions of the C-terminal part of VirD2 led to lack of transfer of T-DNA but, for the first time, we report that virulence is restored when these truncations are supplemented at the C terminus by a short translocation signal from the VirF protein. The lack of virulence of C-terminal deletions suggests that the C-terminal part contains all or part of the translocation signal of VirD2. Using a novel series of mutant VirD2 proteins, the C-terminal half of VirD2 was further investigated. We demonstrate that the C-terminal 40 amino acids of VirD2, which include the NLS and ω, contain all or part of the translocation domain necessary for transport of VirD2 into plant cells, while another element is present in the middle of the protein. The finding that a type IV secretion system transport signal at the C terminus of VirD2 is necessary for virulence provides evidence for the role of VirD2 as a pilot protein driving translocation of the T-strand.

Factor Xa Enhances the Binding of Tissue Factor Pathway Inhibitor to Acidic Phospholipids

1996 ◽  
Vol 75 (05) ◽  
pp. 796-800 ◽  
Author(s):  
Sanne Valentin ◽  
Inger Schousboe
Keyword(s):  
Tissue Factor ◽  
Tissue Factor Pathway Inhibitor ◽  
Factor Xa ◽  
Microtitre Plate ◽  
C Terminus ◽  
Microtitre Plate Assay ◽  
Kunitz Domain ◽  
Tissue Factor Pathway ◽  
Acidic Phospholipids

SummaryIn the present study, the interaction between tissue factor pathway inhibitor (TFPI) and phospholipids has been characterized using a microtitre plate assay. TFPI was shown to bind calcium-independently to an acidic phospholipid surface composed of phosphatidylserine, but not a surface composed of the neutral phosphatidylcholine. The interaction was demonstrated to be dependent on the presence of the TFPI C-terminus. The presence of heparin (1 U/ml, unfractionated) was able to significantly reduce the binding of TFPI to phospholipid. The interaction of TFPI with phosphatidylserine was significantly decreased in the presence of calcium, but this was counteracted, and even enhanced, following complex formation of TFPI with factor Xa prior to incubation with the phospholipid surface. Moreover, a TFPI variant, not containing the third Kunitz domain and the C-terminus, was unable to bind to phospholipid. However, following the formation of a TFPI/factor Xa-complex this TFPI variant was capable of interacting with the phospholipid surface. This indicates that the role of factor Xa as a TFPI cofactor, at least in part, is to mediate the binding of TFPI to the phospholipid surface.

Role of key point Mutations in Receptor Binding Domain of SARS-CoV-2 Spike Glycoprotein

2020 ◽  
Vol 20 ◽  
Author(s):  
Bipin Singh
Keyword(s):  
Receptor Binding ◽  
Point Mutations ◽  
Binding Domain ◽  
Receptor Binding Domain ◽  
Spike Glycoprotein ◽  
Angiotensin Converting Enzyme 2 ◽  
Recent Outbreak ◽  
Novel Coronavirus ◽  
Genomic Similarity

: The recent outbreak of novel coronavirus (SARS-CoV-2 or 2019-nCoV) and its worldwide spread is posing one of the major threats to human health and the world economy. It has been suggested that SARS-CoV-2 is similar to SARSCoV based on the comparison of the genome sequence. Despite the genomic similarity between SARS-CoV-2 and SARSCoV, the spike glycoprotein and receptor binding domain in SARS-CoV-2 shows the considerable difference compared to SARS-CoV, due to the presence of several point mutations. The analysis of receptor binding domain (RBD) from recently published 3D structures of spike glycoprotein of SARS-CoV-2 (Yan, R., et al. (2020); Wrapp, D., et al. (2020); Walls, A. C., et al. (2020)) highlights the contribution of a few key point mutations in RBD of spike glycoprotein and molecular basis of its efficient binding with human angiotensin-converting enzyme 2 (ACE2).

scholarly journals A CACNA1A variant associated with trigeminal neuralgia alters the gating of Cav2.1 channels

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Eder Gambeta ◽  
Maria A. Gandini ◽  
Ivana A. Souza ◽  
Laurent Ferron ◽  
Gerald W. Zamponi
Keyword(s):  
Trigeminal Neuralgia ◽  
Missense Mutation ◽  
Neurotransmitter Release ◽  
Trigeminal System ◽  
Wild Type ◽  
Calcium Dependent ◽  
Whole Cell Patch Clamp ◽  
C Terminus ◽  
Dependent Inactivation

AbstractA novel missense mutation in the CACNA1A gene that encodes the pore forming α1 subunit of the CaV2.1 voltage-gated calcium channel was identified in a patient with trigeminal neuralgia. This mutation leads to a substitution of proline 2455 by histidine (P2455H) in the distal C-terminus region of the channel. Due to the well characterized role of this channel in neurotransmitter release, our aim was to characterize the biophysical properties of the P2455H variant in heterologously expressed CaV2.1 channels. Whole-cell patch clamp recordings of wild type and mutant CaV2.1 channels expressed in tsA-201 cells reveal that the mutation mediates a depolarizing shift in the voltage-dependence of activation and inactivation. Moreover, the P2455H mutant strongly reduced calcium-dependent inactivation of the channel that is consistent with an overall gain of function. Hence, the P2455H CaV2.1 missense mutation alters the gating properties of the channel, suggesting that associated changes in CaV2.1-dependent synaptic communication in the trigeminal system may contribute to the development of trigeminal neuralgia.

Thermotropic lipid and protein transitions in Chinese hamster lung cell membranes: relationship to hyperthermic cell killing

1983 ◽  
Vol 61 (6) ◽  
pp. 421-427 ◽  
Author(s):  
James R. Lepock ◽  
Kwan-Hon Cheng ◽  
Hisham Al-Qysi ◽  
Jack Kruuv
Keyword(s):  
Mammalian Cells ◽  
Plasma Membranes ◽  
Chinese Hamster ◽  
Cell Killing ◽  
Water Soluble ◽  
Growth Data ◽  
Protein Fluorescence ◽  
Polar Groups ◽  
Spin Resonance ◽  
Intrinsic Protein Fluorescence

Exposure of mammalian cells to hyperthermic temperatures (ca. 41–45 °C) appears to act as a direct or triggering effect to produce some later response such as cell death, thermotolerance, or heat-shock protein synthesis. The high activation energy of cell killing indicates that the direct effect of hyperthermia might be a thermotropic transition in some cellular component, for this particular response. Both hyperthermic survival and growth data imply that the temperature for the onset of hyperthermic cell killing is 40–41.5 °C for Chinese hamster lung V79 cells. Studies using the electron spin resonance label 2,2-dimethyl-5-dodecyl-5-methyloxazolidine-N-oxide and the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene show the existence of lipid transitions at approximately 7–8 and 23–36 °C (or a broad transition between these temperatures) in mitochondria and whole cell homogenates, that correlate well with changes in growth and hypothermic killing. No lipid transition was detected near 40–41.5 °C that could correlate with hyperthermic killing in either mitochondrial or plasma membranes, but measurements of intrinsic protein fluorescence and protein fluorophore to trans-paranaric acid energy transfer demonstrate the existence of an irreversible transition in protein structure or arrangement above ca. 40 °C in both mitochondrial and plasma membranes. This transition is due to protein rearrangement and (or) unfolding such that there is increased exposure of protein tryptophan and tyrosine residues to polar groups and to paranaric acid. The strength of the transition implies that a significant fraction of total membrane protein is involved in this transition, which may be analogous to the heat-induced denaturation of water-soluble proteins. This alteration in membrane structure above ca. 40 °C could cause many of the observed changes in plasma membrane and mitochondrial function, which may further be involved in cellular responses to hyperthermia.

The role of the C-terminus and Kpn loop in the quaternary structure stability of nucleoside diphosphate kinase from Leishmania parasites

2015 ◽  
Vol 192 (3) ◽  
pp. 336-341 ◽  
Author(s):  
Plínio Salmazo Vieira ◽  
Priscila Oliveira de Giuseppe ◽  
Arthur Henrique Cavalcante de Oliveira ◽  
Mario Tyago Murakami
Keyword(s):  
Quaternary Structure ◽  
Nucleoside Diphosphate Kinase ◽  
Structure Stability ◽  
C Terminus ◽  
Leishmania Parasites
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