scholarly journals Evolution of Plant Na+-P-Type ATPases: From Saline Environments to Land Colonization

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 221
Author(s):  
Siarhei A. Dabravolski ◽  
Stanislav V. Isayenkov
Keyword(s):  
Binding Site ◽  
Common Ancestor ◽  
Domain Architecture ◽  
Transport Proteins ◽  
Transport Systems ◽  
Α Subunit ◽  
Land Colonization ◽  
Major Factors ◽  
Membrane Pumps ◽  
P Type

Soil salinity is one of the major factors obstructing the growth and development of agricultural crops. Eukaryotes have two main transport systems involved in active Na+ removal: cation/H+ antiporters and Na+-P-type ATPases. Key transport proteins, Na+/K+-P-ATPases, are widely distributed among the different taxa families of pumps which are responsible for keeping cytosolic Na+ concentrations below toxic levels. Na+/K+-P-ATPases are considered to be absent in flowering plants. The data presented here are a complete inventory of P-type Na+/K+-P-ATPases in the major branches of the plant kingdom. We also attempt to elucidate the evolution of these important membrane pumps in plants in comparison with other organisms. We were able to observe the gradual replacement of the Na+-binding site to the Ca2+-binding site, starting with cyanobacteria and moving to modern land plants. Our results show that the α-subunit likely evolved from one common ancestor to bacteria, fungi, plants, and mammals, whereas the β-subunit did not evolve in green algae. In conclusion, our results strongly suggest the significant differences in the domain architecture and subunit composition of plant Na+/K+-P-ATPases depending on plant taxa and the salinity of the environment. The obtained data clarified and broadened the current views on the evolution of Na+/K+-P-ATPases. The results of this work would be helpful for further research on P-type ATPase functionality and physiological roles.

scholarly journals Deciphering ion transport and ATPase coupling in the intersubunit tunnel of KdpFABC

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jakob M. Silberberg ◽  
Robin A. Corey ◽  
Lisa Hielkema ◽  
Charlott Stock ◽  
Phillip J. Stansfeld ◽  
...  
Keyword(s):  
Binding Site ◽  
Common Ancestor ◽  
Atp Hydrolysis ◽  
Md Simulations ◽  
High Affinity ◽  
Ion Translocation ◽  
Biochemical Assays ◽  
Subunit Interface ◽  
Translocation Mechanism ◽  
P Type

AbstractKdpFABC, a high-affinity K+ pump, combines the ion channel KdpA and the P-type ATPase KdpB to secure survival at K+ limitation. Here, we apply a combination of cryo-EM, biochemical assays, and MD simulations to illuminate the mechanisms underlying transport and the coupling to ATP hydrolysis. We show that ions are transported via an intersubunit tunnel through KdpA and KdpB. At the subunit interface, the tunnel is constricted by a phenylalanine, which, by polarized cation-π stacking, controls K+ entry into the canonical substrate binding site (CBS) of KdpB. Within the CBS, ATPase coupling is mediated by the charge distribution between an aspartate and a lysine. Interestingly, individual elements of the ion translocation mechanism of KdpFABC identified here are conserved among a wide variety of P-type ATPases from different families. This leads us to the hypothesis that KdpB might represent an early descendant of a common ancestor of cation pumps.

scholarly journals Deciphering ion transport and ATPase coupling in the intersubunit tunnel of KdpFABC

2021 ◽  
Author(s):  
Jakob M Silberberg ◽  
Robin A Corey ◽  
Lisa Hielkema ◽  
Charlott Stock ◽  
Phillip James Stansfeld ◽  
...  
Keyword(s):  
Binding Site ◽  
Common Ancestor ◽  
Atp Hydrolysis ◽  
Md Simulations ◽  
High Affinity ◽  
Ion Translocation ◽  
Biochemical Assays ◽  
Subunit Interface ◽  
Translocation Mechanism ◽  
P Type

KdpFABC, a high-affinity K+ pump, combines the ion channel KdpA and the P-type ATPase KdpB to secure survival at K+ limitation. Here, we apply a combination of cryo-EM, biochemical assays, and MD simulations to illuminate the mechanisms underlying transport and the coupling to ATP hydrolysis. We unambiguously show that ions are transported via an intersubunit tunnel through KdpA and KdpB. At the subunit interface, the tunnel is constricted by a phenylalanine, which, by polarized cation-π stacking, controls K+ entry into the canonical substrate binding site (CBS) of KdpB. Within the CBS, ATPase coupling is mediated by the charge distribution between an aspartate and a lysine. Interestingly, individual elements of the ion translocation mechanism of KdpFABC identified here are conserved among a wide variety of P-type ATPases from different families. This leads us to the hypothesis that KdpB might represent an early descendant of a common ancestor of cation pumps.

Order-disorder transitions of cytoplasmic N-termini in the mechanisms of P-type ATPases

2020 ◽  
Author(s):  
Khondker Rufaka Hossain ◽  
Daniel Clayton ◽  
Sophia C Goodchild ◽  
Alison Rodger ◽  
Richard James Payne ◽  
...  
Keyword(s):  
Protein Structure ◽  
Membrane Protein ◽  
Structure And Function ◽  
Membrane Protein Structure ◽  
Protein Structure And Function ◽  
Lipid Environment ◽  
Membrane Pumps ◽  
And Function ◽  
P Type

Membrane protein structure and function are modulated via interactions with their lipid environment. This is particularly true for the integral membrane pumps, the P-type ATPases. These ATPases play vital roles...

scholarly journals Silencing of the Gene for the α-Subunit of Human Chorionic Gonadotropin by the Embryonic Transcription Factor Oct-3/4

1997 ◽  
Vol 11 (11) ◽  
pp. 1651-1658 ◽  
Author(s):  
Limin Liu ◽  
Douglas Leaman ◽  
Michel Villalta ◽  
R. Michael Roberts
Keyword(s):  
Transcription Factor ◽  
Binding Site ◽  
Gene Promoter ◽  
Site Directed Mutagenesis ◽  
Mobility Shift ◽  
Α Subunit ◽  
Choriocarcinoma Cells ◽  
Human Choriocarcinoma Cells ◽  
Electrophoretic Mobility Shift Assays ◽  
Jar Cells

Abstract CG is required for maintenance of the corpus luteum during pregnancy in higher primates. As CG is a heterodimeric molecule, some form of coordinated control must be maintained over the transcription of its two subunit genes. We recently found that expression of human CG β-subunit (hCGβ) in JAr human choriocarcinoma cells was almost completely silenced by the embryonic transcription factor Oct-3/4, which bound to a unique ACAATAATCA octameric sequence in the hCGβ gene promoter. Here we report that Oct-3/4 is also a potent inhibitor of hCG α-subunit (hCGα) expression in JAr cells. Oct-3/4 reduced human GH reporter expression from the −170 hCGα promoter in either the presence or absence of cAMP by about 70% in transient cotransfection assays, but had no effect on expression from either the −148 hCGα or the −99 hCGα promoter. Unexpectedly, no Oct-3/4-binding site was identified within the −170 to −148 region of the hCGα promoter, although one was found around position −115 by both methylation interference footprinting and electrophoretic mobility shift assays. Site-directed mutagenesis of this binding site destroyed the affinity of the promoter for Oct-3/4, but did not affect repression of the promoter. Therefore, inhibition of hCGα gene transcription by Oct-3/4 appears not to involve direct binding of this factor to the site responsible for silencing. When stably transfected into JAr cells, Oct-3/4 reduced the amounts of both endogenous hCGα mRNA and protein by 70–80%. Oct-3/4 is therefore capable of silencing both hCGα and hCGβ gene expression. We suggest that as the trophoblast begins to form, reduction of Oct-3/4 expression permits the coordinated onset of transcription from the hCGα and hCGβ genes.

Evolution of vacuolar H+-ATPases: immunological relationships of the nucleotide-binding subunits

1989 ◽  
Vol 67 (6) ◽  
pp. 306-310 ◽  
Author(s):  
Morris F. Manolson ◽  
Judith M. Percy ◽  
David K. Apps ◽  
Xiao-Song Xie ◽  
Dennis K. Stone ◽  
...  
Keyword(s):  
Anaerobic Bacterium ◽  
Common Ancestor ◽  
Sequence Data ◽  
Structural Features ◽  
Eukaryotic Cells ◽  
Clostridium Pasteurianum ◽  
Chromaffin Granules ◽  
Α Subunit ◽  
Evolutionary Origins ◽  
Vacuolar Membranes

The evolution of the endomembrane systems of eukaryotic cells can be examined by exploring the evolutionary origins of the endomembrane H+-ATPases. Recent studies suggest that certain polypeptides are common to all H+ pumps of this type. Tonoplast H+ -ATPase from Beta vulgaris L. was purified and antibodies raised to two of its subunits. Each of these antisera reacted with a polypeptide of the corresponding size in bovine chromaffin granules, bovine clathrincoated vesicles, and yeast vacuolar membranes, suggesting common structural features and a common ancestor for endomembrane H+-ATPases of different organelles and different kingdoms. The antiserum raised against the 57-kDa polypeptide of plant tonoplast H+ -ATPase also reacted with subunit "a" of the H+-ATPase from the obligately anaerobic bacterium Clostridium pasteurianum and to the α subunit of the H+ -ATPase from Escherichia coli. There was no reactivity with chloroplast or mitochondrial ATPases. These results are discussed in relation to recent sequence data which suggest that endomembrane H+-ATPases may be evolutionarily related to the F0F1 ATPases.Key words: H+ -ATPase, evolution, immunology, vacuole, endomembrane.

scholarly journals On the Interaction between Amiloride and Its Putative α-Subunit Epithelial Na+Channel Binding Site

2005 ◽  
Vol 280 (28) ◽  
pp. 26206-26215 ◽  
Author(s):  
Ossama B. Kashlan ◽  
Shaohu Sheng ◽  
Thomas R. Kleyman
Keyword(s):  
Binding Site ◽  
Na Channel ◽  
Α Subunit ◽  
Epithelial Na Channel

scholarly journals Hyperpolarization-activated inward leakage currents caused by deletion or mutation of carboxy-terminal tyrosines of the Na+/K+-ATPase α subunit

2010 ◽  
Vol 135 (2) ◽  
pp. 115-134 ◽  
Author(s):  
Susan Meier ◽  
Neslihan N. Tavraz ◽  
Katharina L. Dürr ◽  
Thomas Friedrich
Keyword(s):  
Binding Site ◽  
Critical Role ◽  
Aromatic Amino Acids ◽  
Cation Binding ◽  
Carboxy Terminus ◽  
Leakage Currents ◽  
Α Subunit ◽  
Inward Currents ◽  
The Common ◽  
Carboxy Terminal

The Na+/K+-ATPase mediates electrogenic transport by exporting three Na+ ions in exchange for two K+ ions across the cell membrane per adenosine triphosphate molecule. The location of two Rb+ ions in the crystal structures of the Na+/K+-ATPase has defined two “common” cation binding sites, I and II, which accommodate Na+ or K+ ions during transport. The configuration of site III is still unknown, but the crystal structure has suggested a critical role of the carboxy-terminal KETYY motif for the formation of this “unique” Na+ binding site. Our two-electrode voltage clamp experiments on Xenopus oocytes show that deletion of two tyrosines at the carboxy terminus of the human Na+/K+-ATPase α2 subunit decreases the affinity for extracellular and intracellular Na+, in agreement with previous biochemical studies. Apparently, the ΔYY deletion changes Na+ affinity at site III but leaves the common sites unaffected, whereas the more extensive ΔKETYY deletion affects the unique site and the common sites as well. In the absence of extracellular K+, the ΔYY construct mediated ouabain-sensitive, hyperpolarization-activated inward currents, which were Na+ dependent and increased with acidification. Furthermore, the voltage dependence of rate constants from transient currents under Na+/Na+ exchange conditions was reversed, and the amounts of charge transported upon voltage pulses from a certain holding potential to hyperpolarizing potentials and back were unequal. These findings are incompatible with a reversible and exclusively extracellular Na+ release/binding mechanism. In analogy to the mechanism proposed for the H+ leak currents of the wild-type Na+/K+-ATPase, we suggest that the ΔYY deletion lowers the energy barrier for the intracellular Na+ occlusion reaction, thus destabilizing the Na+-occluded state and enabling inward leak currents. The leakage currents are prevented by aromatic amino acids at the carboxy terminus. Thus, the carboxy terminus of the Na+/K+-ATPase α subunit represents a structural and functional relay between Na+ binding site III and the intracellular cation occlusion gate.

scholarly journals Cell Cycle Localization, Dimerization, and Binding Domain Architecture of the Telomere Protein cPot1

2004 ◽  
Vol 24 (5) ◽  
pp. 2091-2102 ◽  
Author(s):  
Chao Wei ◽  
Carolyn M. Price
Keyword(s):  
Cell Cycle ◽  
Dna Binding ◽  
Binding Site ◽  
Domain Architecture ◽  
Binding Domain ◽  
Binding Motif ◽  
Dna Binding Domain ◽  
Telomere Protein ◽  
Ob Fold

ABSTRACT Pot1 is a single-stranded-DNA-binding protein that recognizes telomeric G-strand DNA. It is essential for telomere capping in Saccharomyces pombe and regulates telomere length in humans. Human Pot1 also interacts with proteins that bind the duplex region of the telomeric tract. Thus, like Cdc13 from S. cerevisiae, Pot 1 may have multiple roles at the telomere. We show here that endogenous chicken Pot1 (cPot1) is present at telomeres during periods of the cell cycle when t loops are thought to be present. Since cPot1 can bind internal loops and directly adjacent DNA-binding sites, it is likely to fully coat and protect both G-strand overhangs and the displaced G strand of a t loop. The minimum binding site of cPot1 is double that of the S. pombe DNA-binding domain. Although cPot can self associate, dimerization is not required for DNA binding and hence does not explain the binding-site duplication. Instead, the DNA-binding domain appears to be extended to contain a second binding motif in addition to the conserved oligonucleotide-oligosaccharide (OB) fold present in other G-strand-binding proteins. This second motif could be another OB fold. Although dimerization is inefficient in vitro, it may be regulated in vivo and could promote association with other telomere proteins and/or telomere compaction.

Bile Salt Transporters: Molecular Characterization, Function, and Regulation

2003 ◽  
Vol 83 (2) ◽  
pp. 633-671 ◽  
Author(s):  
Michael Trauner ◽  
James L. Boyer
Keyword(s):  
Bile Salt ◽  
Molecular Characterization ◽  
Bile Salts ◽  
Organic Anion ◽  
Transport Proteins ◽  
Salt Transport ◽  
Transport Systems ◽  
Cholestatic Liver Disease ◽  
Bile Salt Transporters ◽  
Bile Salt Transport

Molecular medicine has led to rapid advances in the characterization of hepatobiliary transport systems that determine the uptake and excretion of bile salts and other biliary constituents in the liver and extrahepatic tissues. The bile salt pool undergoes an enterohepatic circulation that is regulated by distinct bile salt transport proteins, including the canalicular bile salt export pump BSEP (ABCB11), the ileal Na+-dependent bile salt transporter ISBT (SLC10A2), and the hepatic sinusoidal Na+- taurocholate cotransporting polypeptide NTCP (SLC10A1). Other bile salt transporters include the organic anion transporting polypeptides OATPs (SLC21A) and the multidrug resistance-associated proteins 2 and 3 MRP2,3 (ABCC2,3). Bile salt transporters are also present in cholangiocytes, the renal proximal tubule, and the placenta. Expression of these transport proteins is regulated by both transcriptional and posttranscriptional events, with the former involving nuclear hormone receptors where bile salts function as specific ligands. During bile secretory failure (cholestasis), bile salt transport proteins undergo adaptive responses that serve to protect the liver from bile salt retention and which facilitate extrahepatic routes of bile salt excretion. This review is a comprehensive summary of current knowledge of the molecular characterization, function, and regulation of bile salt transporters in normal physiology and in cholestatic liver disease and liver regeneration.

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