scholarly journals Characterization of SCaMC-3-like/slc25a41, a novel calcium-independent mitochondrial ATP-Mg/Pi carrier

2009 ◽  
Vol 418 (1) ◽  
pp. 125-133 ◽  
Author(s):  
Javier Traba ◽  
Jorgina Satrústegui ◽  
Araceli del Arco
Keyword(s):  
Calcium Binding ◽  
Adenine Nucleotide ◽  
Duplication Event ◽  
Intermembrane Space ◽  
Inner Mitochondrial Membrane ◽  
Mitochondrial Carriers ◽  
Calcium Dependent ◽  
Mammalian Genomes ◽  
Ef Hands

The SCaMCs (small calcium-binding mitochondrial carriers) constitute a subfamily of mitochondrial carriers responsible for the ATP-Mg/Pi exchange with at least three paralogues in vertebrates. SCaMC members are proteins with two functional domains, the C-terminal transporter domain and the N-terminal domain which harbours calcium-binding EF-hands and faces the intermembrane space. In the present study, we have characterized a shortened fourth paralogue, SCaMC-3L (SCaMC-3-like; also named slc25a41), which lacks the calcium-binding N-terminal extension. SCaMC-3L orthologues are found exclusively in mammals, showing approx. 60% identity to the C-terminal half of SCaMC-3, its closest paralogue. In mammalian genomes, SCaMC-3 and SCaMC-3L genes are adjacent on the same chromosome, forming a head-to-tail tandem array, and show identical exon–intron boundaries, indicating that SCaMC-3L could have arisen from an SCaMC-3 ancestor by a partial duplication event which occurred prior to mammalian radiation. Expression and functional data suggest that, following the duplication event, SCaMC-3L has acquired more restrictive functions. Unlike the broadly expressed longer SCaMCs, mouse SCaMC-3L shows a limited expression pattern; it is preferentially expressed in testis and, at lower levels, in brain. SCaMC-3L transport activity was studied in yeast deficient in Sal1p, the calcium-dependent mitochondrial ATP-Mg/Pi carrier, co-expressing SCaMC-3L and mitochondrial-targeted luciferase, and it was found to perform ATP-Mg/Pi exchange, in a similar manner to Sal1p or other ATP-Mg/Pi carriers. However, metabolite transport through SCaMC-3L is calcium-independent, representing a novel mechanism involved in adenine nucleotide transport across the inner mitochondrial membrane, different to ADP/ATP translocases or long SCaMC paralogues.

Characterization of a second member of the subfamily of calcium-binding mitochondrial carriers expressed in human non-excitable tissues

2000 ◽  
Vol 345 (3) ◽  
pp. 725-732 ◽  
Author(s):  
Araceli DEL ARCO ◽  
Marta AGUDO ◽  
Jorgina SATRÚSTEGUI
Keyword(s):  
Calcium Binding ◽  
Chromosome Band ◽  
Sufficient Information ◽  
Type Ii ◽  
Mitochondrial Carriers ◽  
High Sequence Conservation ◽  
Ef Hands ◽  
The Right ◽  
Very High

We have recently identified a subfamily of mitochondrial carriers that bind calcium, and cloned ARALAR1, a member of this subfamily expressed in human muscle and brain. We have now cloned a second human ARALAR gene (ARALAR2) coding for a protein 78.3% identical to Aralar1, but expressed in liver and non-excitable tissues. Aralar2 is identical to citrin, the product of the gene mutated in type-II citrullinaemia [Kobayashi, Sinasac, Iijima, Boright, Begum, Lee, Yasuda, Ikeda, Hirano, Terazono et al. (1999) Nat. Genet. 22, 159-163]. A related protein, DmAralar, 69% identical to Aralar1, was found in Drosophila melanogaster, the DMARALAR locus lying on the right arm of the third chromosome, band 99F. The N-terminal half of Aralar2/citrin is able to bind calcium and this requires the presence of the two most distal EF-hands. The localization of Aralar2/citrin expressed in human cell lines is mitochondrial, the C-terminal half containing sufficient information for import and assembly into mitochondria. The C-terminal half of Aralar proteins is related to the yeast YPR020c gene, with a very high sequence conservation (54.3% identity), suggesting that these proteins play an important role. Thus Aralar proteins are probably expressed in all tissues in an isoform-specific fashion, where they function as calcium-regulated metabolite (possibly anionic) carriers.

P1, P5-Bis-(5′-adenosyl)pentaphosphate: Is this Adenylate Kinase Inhibitor Substrate for Mitochondrial Processes?

1977 ◽  
Vol 32 (9-10) ◽  
pp. 786-791 ◽  
Author(s):  
Josef Köhrle ◽  
Joachim Lüstorff ◽  
Eckhard Schlimme
Keyword(s):  
Adenylate Kinase ◽  
Kinase Inhibitor ◽  
Adenine Nucleotide ◽  
Nucleoside Diphosphate Kinase ◽  
Liver Mitochondria ◽  
Inhibitory Effect ◽  
Rat Liver Mitochondria ◽  
Intermembrane Space ◽  
Rabbit Muscle ◽  
Inner Mitochondrial Membrane

Abstract 1. P1, P5-Bis-(5′-adenosyl)pentaphosphate (Ap5A) inhibits “soluble” adenylate kinase even when this enzyme is an integral part of the complete mitochondrion. The Ki is 10-5м , i. e. about two orders of magnitude higher than the inhibitor constants determined for the purified adenylate kinase of rabbit muscle and an enzyme preparation separated from the mitochondrial intermembrane space. The weaker inhibitory effect is due to a lower accessibility of the enzyme.2. As to be expected Ap5A which is of the “multisubstrate analogue”-type does not affect mito­ chondrial nucleoside diphosphate kinase.3. Though Ap5A owns the structural elements of both ATP and ADP it is not a substrate of the adenine nucleotide carrier, i.e. neither it is exchanged across the inner mitochondrial membrane nor specifically bound.4. Ap5A is not metabolized by rat liver mitochondria.

scholarly journals Calmodulin and Calmodulin Binding Proteins in Dictyostelium: A Primer

2020 ◽  
Vol 21 (4) ◽  
pp. 1210
Author(s):  
Danton H. O’Day ◽  
Ryan J. Taylor ◽  
Michael A. Myre
Keyword(s):  
Conformational Changes ◽  
Calcium Binding ◽  
Binding Proteins ◽  
Regulatory Protein ◽  
Model Organism ◽  
Ion Binding ◽  
Calcium Dependent ◽  
Calmodulin Binding ◽  
Human Counterpart ◽  
Ef Hands

Dictyostelium discoideum is gaining increasing attention as a model organism for the study of calcium binding and calmodulin function in basic biological events as well as human diseases. After a short overview of calcium-binding proteins, the structure of Dictyostelium calmodulin and the conformational changes effected by calcium ion binding to its four EF hands are compared to its human counterpart, emphasizing the highly conserved nature of this central regulatory protein. The calcium-dependent and -independent motifs involved in calmodulin binding to target proteins are discussed with examples of the diversity of calmodulin binding proteins that have been studied in this amoebozoan. The methods used to identify and characterize calmodulin binding proteins is covered followed by the ways Dictyostelium is currently being used as a system to study several neurodegenerative diseases and how it could serve as a model for studying calmodulinopathies such as those associated with specific types of heart arrythmia. Because of its rapid developmental cycles, its genetic tractability, and a richly endowed stock center, Dictyostelium is in a position to become a leader in the field of calmodulin research.

scholarly journals Insights into the evolution of regulated actin dynamics via characterization of primitive gelsolin/cofilin proteins from Asgard archaea

2020 ◽  
Vol 117 (33) ◽  
pp. 19904-19913 ◽  
Author(s):  
Caner Akıl ◽  
Linh T. Tran ◽  
Magali Orhant-Prioux ◽  
Yohendran Baskaran ◽  
Edward Manser ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Actin Filament ◽  
Calcium Binding ◽  
Mammalian Cells ◽  
Actin Polymerization ◽  
Calcium Release ◽  
Duplication Event ◽  
Cellular Level ◽  
Actin Dynamics

Asgard archaea genomes contain potential eukaryotic-like genes that provide intriguing insight for the evolution of eukaryotes. The eukaryotic actin polymerization/depolymerization cycle is critical for providing force and structure in many processes, including membrane remodeling. In general, Asgard genomes encode two classes of actin-regulating proteins from sequence analysis, profilins and gelsolins. Asgard profilins were demonstrated to regulate actin filament nucleation. Here, we identify actin filament severing, capping, annealing and bundling, and monomer sequestration activities by gelsolin proteins from Thorarchaeota (Thor), which complete a eukaryotic-like actin depolymerization cycle, and indicate complex actin cytoskeleton regulation in Asgard organisms. Thor gelsolins have homologs in other Asgard archaea and comprise one or two copies of the prototypical gelsolin domain. This appears to be a record of an initial preeukaryotic gene duplication event, since eukaryotic gelsolins are generally comprise three to six domains. X-ray structures of these proteins in complex with mammalian actin revealed similar interactions to the first domain of human gelsolin or cofilin with actin. Asgard two-domain, but not one-domain, gelsolins contain calcium-binding sites, which is manifested in calcium-controlled activities. Expression of two-domain gelsolins in mammalian cells enhanced actin filament disassembly on ionomycin-triggered calcium release. This functional demonstration, at the cellular level, provides evidence for a calcium-controlled Asgard actin cytoskeleton, indicating that the calcium-regulated actin cytoskeleton predates eukaryotes. In eukaryotes, dynamic bundled actin filaments are responsible for shaping filopodia and microvilli. By correlation, we hypothesize that the formation of the protrusions observed from Lokiarchaeota cell bodies may involve the gelsolin-regulated actin structures.

Characterization of Arabidopsis calcium-dependent protein kinases: activated or not by calcium?

2012 ◽  
Vol 447 (2) ◽  
pp. 291-299 ◽  
Author(s):  
Marie Boudsocq ◽  
Marie-Jo Droillard ◽  
Leslie Regad ◽  
Christiane Laurière
Keyword(s):  
Protein Kinases ◽  
Calcium Binding ◽  
Molecular Mechanisms ◽  
Calcium Sensitivity ◽  
In Planta ◽  
Calcium Dependent ◽  
Dependent Protein ◽  
Biochemical Level ◽  
Calcium Dependent Protein Kinases ◽  
Ef Hands

CDPKs (calcium-dependent protein kinases), which contain both calmodulin-like calcium binding and serine/threonine protein kinase domains, are only present in plants and some protozoans. Upon activation by a stimulus, they transduce the signal through phosphorylation cascades to induce downstream responses, including transcriptional regulation. To understand the functional specificities of CDPKs, 14 Arabidopsis CPKs (CDPKs in plants) representative of the three main subgroups were characterized at the biochemical level, using HA (haemagglutinin)-tagged CPKs expressed in planta. Most of them were partially or mainly associated with membranes, in agreement with acylation predictions. Importantly, CPKs displayed highly variable calcium-dependences for their kinase activities: seven CPKs from subgroups 1 and 2 were clearly sensitive to calcium with different intensities, whereas six CPKs from subgroup 3 exhibited low or no calcium sensitivity to two generic substrates. Interestingly, this apparent calcium-independence correlated with significant alterations in the predicted EF-hands of these kinases, although they all bound calcium. The noticeable exception, CPK25, was calcium-independent owing to the absence of functional EF-hands. Taken together, the results of the present study suggest that calcium binding differentially affects CDPK isoforms that may be activated by distinct molecular mechanisms.

scholarly journals The S2–S3 Loop of Kv7.4 Channels Is Essential for Calmodulin Regulation of Channel Activation

2021 ◽  
Vol 11 ◽  
Author(s):  
Wenhui Zhuang ◽  
Zhiqiang Yan
Keyword(s):  
Calcium Binding ◽  
Auditory Pathway ◽  
Inhibitory Effect ◽  
Binding Ability ◽  
Double Mutation ◽  
Calcium Dependent ◽  
Kv7 Channels ◽  
Electrophysiological Recordings ◽  
Ef Hands ◽  
Cam Regulation

Kv7.4 (KCNQ4) voltage-gated potassium channels control excitability in the inner ear and the central auditory pathway. Mutations in Kv7.4 channels result in inherited progressive deafness in humans. Calmodulin (CaM) is crucial for regulating Kv7 channels, but how CaM affects Kv7 activity has remained unclear. Here, based on electrophysiological recordings, we report that the third EF hand (EF3) of CaM controls the calcium-dependent regulation of Kv7.4 activation and that the S2–S3 loop of Kv7.4 is essential for the regulation mediated by CaM. Overexpression of the mutant CaM1234, which loses the calcium binding ability of all four EF hands, facilitates Kv7.4 activation by accelerating activation kinetics and shifting the voltage dependence of activation leftwards. The single mutant CaM3, which loses the calcium binding ability of the EF3, phenocopies facilitating effects of CaM1234 on Kv7.4 activation. Kv7.4 channels co-expressed with wild-type (WT) CaM show inhibited activation when intracellular calcium levels increase, while Kv7.4 channels co-expressed with CaM1234 or CaM3 are insensitive to calcium. Mutations C156A, C157A, C158V, R159, and R161A, which are located within the Kv7.4 S2–S3 loop, dramatically facilitate activation of Kv7.4 channels co-expressed with WT CaM but have no effect on activation of Kv7.4 channels co-expressed with CaM3, indicating that these five mutations decrease the inhibitory effect of Ca2+/CaM. The double mutation C156A/R159A decreases Ca2+/CaM binding and completely abolishes CaM-mediated calcium-dependent regulation of Kv7.4 activation. Taken together, our results provide mechanistic insights into CaM regulation of Kv7.4 activation and highlight the crucial role of the Kv7.4 S2–S3 loop in CaM regulation.

scholarly journals Molecular Players of EF-hand Containing Calcium Signaling Event in Plants

2019 ◽  
Vol 20 (6) ◽  
pp. 1476 ◽  
Author(s):  
Tapan Mohanta ◽  
Dhananjay Yadav ◽  
Abdul Khan ◽  
Abeer Hashem ◽  
Elsayed Abd_Allah ◽  
...  
Keyword(s):  
Calcium Signaling ◽  
Protein Kinases ◽  
Calcium Binding ◽  
Life Forms ◽  
Terrestrial Environment ◽  
Calcium Dependent ◽  
Ef Hand ◽  
Dependent Protein ◽  
Calcium Dependent Protein Kinases ◽  
Ef Hands

Ca2+ is a universal second messenger that plays a pivotal role in diverse signaling mechanisms in almost all life forms. Since the evolution of life from an aquatic to a terrestrial environment, Ca2+ signaling systems have expanded and diversified enormously. Although there are several Ca2+ sensing molecules found in a cell, EF-hand containing proteins play a principal role in calcium signaling event in plants. The major EF-hand containing proteins are calmodulins (CaMs), calmodulin like proteins (CMLs), calcineurin B-like (CBL) and calcium dependent protein kinases (CDPKs/CPKs). CaMs and CPKs contain calcium binding conserved D-x-D motifs in their EF-hands (one motif in each EF-hand) whereas CMLs contain a D-x3-D motif in the first and second EF-hands that bind the calcium ion. Calcium signaling proteins form a complex interactome network with their target proteins. The CMLs are the most primitive calcium binding proteins. During the course of evolution, CMLs are evolved into CaMs and subsequently the CaMs appear to have merged with protein kinase molecules to give rise to calcium dependent protein kinases with distinct and multiple new functions. Ca2+ signaling molecules have evolved in a lineage specific manner with several of the calcium signaling genes being lost in the monocot lineage.

scholarly journals Fungal Genomes: Suffering with Functional Annotation Errors

2020 ◽  
Author(s):  
Tapan Kumar Mohanta ◽  
Abeer Hashem ◽  
Elsayed Fathi Abd_Allah ◽  
Ahmed AL Harrasi
Keyword(s):  
Calcium Binding ◽  
Functional Annotation ◽  
Sequence Data ◽  
Protein Sequences ◽  
Fungal Species ◽  
Sequencing Data ◽  
Calcium Dependent ◽  
Dependent Protein ◽  
Ef Hands ◽  
Annotation Errors

Abstract Background The genome sequencing data are accumulating at a rapid pace, with the current genome sequence data of more than 5780 species being publicly available at the National Center for Biotechnology Information (NCBI) database alone. However, for the researcher communities to use these data, an error-free functional annotation report is a must. Results Analyses of the whole proteome sequence data of 689 fungal species (7.15 million protein sequences) to find the presence of functional annotation error in several species. Hence, calcium dependent protein kinases (CDPKs) and selenoproteins were targeted for the analysis as it is absent all across the fungi kingdom. The analyses revealed the presence of protein with the functional annotation name CDPK. InterproScan analysis revealed that, none of the protein sequences tagged with name “calcium dependent protein kinase” was found to encode calcium binding EF-hands at the regulatory domain. Similarly, none of a protein sequences with annotation name associated with “selenocysteine” was found to encode Sec (U) amino acid. Conclusion The presence of naming of such functional annotation errors in the fungal kingdom is raised a great concern and need to address it at the earliest possible time.

scholarly journals Characterization of SMOC-2, a modular extracellular calcium-binding protein

2003 ◽  
Vol 373 (3) ◽  
pp. 805-814 ◽  
Author(s):  
Christian VANNAHME ◽  
Silke GÖSLING ◽  
Mats PAULSSON ◽  
Patrik MAURER ◽  
Ursula HARTMANN
Keyword(s):  
Calcium Binding ◽  
Binding Domain ◽  
The Novel ◽  
Northern Blots ◽  
Calcium Dependent ◽  
Reverse Transcription Pcr ◽  
Ef Hand ◽  
Human And Mouse ◽  
Calcium Binding Domain

We have isolated the novel gene SMOC-2, which encodes a secreted modular protein containing an EF-hand calcium-binding domain homologous to that in BM-40. It further consists of two thyroglobulin-like domains, a follistatin-like domain and a novel domain found only in the homologous SMOC-1. Phylogenetic analysis of the calcium-binding domain sequences showed that SMOC-1 and −2 form a separate group within the BM-40 family. The human and mouse SMOC-2 sequences are coded for by genes consisting of 13 exons located on chromosomes 6 and 17, respectively. Analysis of recombinantly expressed protein showed that SMOC-2 is a glycoprotein with a calcium-dependent conformation. Results from Northern blots and reverse transcription PCR revealed a widespread expression in many tissues.

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