Small-angle x-ray scattering study of calmodulin bound to two peptides corresponding to parts of the calmodulin-binding domain of the plasma membrane calcium pump

Kataoka, Mikio; Head, James F.; Vorherr, Thomas; Krebs, Joachim; Carafoli, Ernesto

doi:10.1021/bi00239a024

Cited by 107 publications

(88 citation statements)

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“…Small angle x-ray scattering experiments with calmodulin and the C20 peptide revealed that only the C-terminal domain of calmodulin bound, and calmodulin remained in an extended, noncollapsed conformation (8). This extended structure was also confirmed by an NMR solution structure of the C20-Ca 2ϩ -calmodulin complex (9).…”

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confidence: 75%

Tryptophan 1093 Is Largely Responsible for the Slow Off Rate of Calmodulin from Plasma Membrane Ca2+ Pump 4b

Penheiter¹,

Caride²,

Enyedi³

et al. 2002

Journal of Biological Chemistry

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Tryptophan 1093 resides in the 28-residue calmodulinbinding/autoinhibitory domain of the plasma membrane Ca 2؉ pump (PMCA). Previous studies with the isolated calmodulin-binding/autoinhibitory peptide from PMCA have shown that mutations of the tryptophan residue decrease the affinity of the peptide for calmodulin and its affinity as an inhibitor of proteolytically activated pump. In this study, the PMCA mutation in which tryptophan 1093 is converted to alanine (W1093A) was constructed in the full-length PMCA isoform 4b. The mutant pump was expressed in COS cells, and its steady state and pre-steady state kinetic properties were examined. The W1093A pump exhibited an increased basal activity in the absence of calmodulin, so the activation was ϳ2-fold (it is 10-fold in the wild type). The W1093A mutation also lowered the steady state affinity for calmodulin from K 0.5 of 9 nM for wild type to 144 nM (assayed at 700 nM free Ca 2؉ ). Pre-steady state measurements of the rate of activation by Ca 2؉ -calmodulin revealed that the W1093A mutant responded 2.5-fold faster to calmodulin. In contrast to these relatively modest effects, the halftime of inactivation of the mutant was reduced by more than 2 orders of magnitude from 41 min to 7 s. We conclude that tryptophan 1093 does not play a substantial role in Ca 2؉ -calmodulin recognition; rather it functions primarily to slow the inactivation of the calmodulinactivated pump.The plasma membrane Ca 2ϩ ATPase or pump (ATP2B1-4, referred to here as PMCA) 1 and the Na ϩ /Ca 2ϩ exchanger are the main mechanisms for removing Ca 2ϩ from the cell. Ca 2ϩ removal is required to maintain a steady Ca 2ϩ disequilibrium of ϳ10 5 between the cytoplasm and the extracellular milieu and to create the Ca 2ϩ spikes, waves, and oscillations that are the most ubiquitous signaling systems in the cell. Regulation of PMCA occurs via allosteric activation by Ca 2ϩ -calmodulin. Before activation, PMCA is inhibited by an intramolecular interaction between the inhibitory domain at the C terminus and the catalytic core of the molecule. The inhibitory domain contains the calmodulin-binding region of the molecule. A rise in intracellular Ca 2ϩ results in 4 Ca 2ϩ binding to calmodulin; the Ca 2ϩ -calmodulin complex then binds to the inhibitory domain, activating the pump. Activation results in an increase in the affinity of the pump for Ca 2ϩ at its transport site as well as an increase in its maximal turnover.PMCA in mammals is encoded by four genes with additional diversity provided by alternate splicing at two or more sites (for a recent review of PMCA genes, splicing variants, and nomenclature, see Strehler and Zacharias (1)). PMCA isoforms differ among themselves in three ways: 1) basal activities in the absence of calmodulin, 2) rates of activation by Ca 2ϩ -calmodulin, and 3) rates of inactivation by calmodulin dissociation. These differences are caused by differences in the interactions between the inhibitory domain, calmodulin, and the catalytic core. The present study investigates the effect of...

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confidence: 75%

Tryptophan 1093 Is Largely Responsible for the Slow Off Rate of Calmodulin from Plasma Membrane Ca2+ Pump 4b

Penheiter¹,

Caride²,

Enyedi³

et al. 2002

Journal of Biological Chemistry

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“…Conserved amino acid residues of CaMBD1 and other CaMBDs were aligned with these important positions. The other CaMBDs were ACA2p (Harper et al, 1998), BCA1p (Malmstrom et al, 1997), plasma membrane Ca 2ϩ pump (PMCA; Kataoka et al, 1991), calcineurin (Kincaid et al, 1988), and calmodulin (CaM) kinase II (Meader et al, 1993). (B) Amino acid residues 21 to 38 of SCA1p, plotted as an ␣-helical wheel.…”

Section: Discussionmentioning

confidence: 99%

Identification of a Calmodulin-Regulated Soybean Ca²⁺-ATPase (SCA1) That Is Located in the Plasma Membrane

et al. 2000

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Ca 2 ؉ -ATPases are key regulators of Ca 2 ؉ ion efflux in all eukaryotes. Animal cells have two distinct families of Ca 2 ؉ pumps, with calmodulin-stimulated pumps (type IIB pumps) found exclusively at the plasma membrane. In plants, no equivalent type IIB pump located at the plasma membrane has been identified at the molecular level, although related isoforms have been identified in non-plasma membrane locations. Here, we identify a plant cDNA, designated SCA1 (for soybean Ca 2 ؉ -ATPase 1), that encodes Ca 2 ؉ -ATPase and is located at the plasma membrane. The plasma membrane localization was determined by sucrose gradient and aqueous two-phase membrane fractionations and was confirmed by the localization of SCA1p tagged with a green fluorescent protein. The Ca 2 ؉ -ATPase activity of the SCA1p was increased approximately sixfold by calmodulin ( K 1/2 ‫ف‬ 10 nM). Two calmodulin binding sequences were identified in the N-terminal domain. An N-terminal truncation mutant that deletes sequence through the two calmodulin binding sites was able to complement a yeast mutant (K616) that was deficient in two endogenous Ca 2 ؉ pumps. Our results indicate that SCA1p is structurally distinct from the plasma membrane-localized Ca 2 ؉ pump in animal cells, belonging instead to a novel family of plant type IIB pumps found in multiple subcellular locations. In plant cells from soybean, expression of this plasma membrane pump was highly and rapidly induced by salt (NaCl) stress and a fungal elicitor but not by osmotic stress. INTRODUCTIONCa 2 ϩ plays a central role as a second messenger in signal transduction of all eukaryotes (Bootman and Berrige, 1995;Clapham, 1995). The transient increase of cytosolic free Ca 2 ϩ concentration, [Ca 2 ϩ ] cyt , is correlated with a variety of external signals such as touch, temperature shift, abscisic acid, auxin, red light, fungal elicitors, salinity/drought, anoxia, gravity, gibberellic acid, cytokinin, oxidative stress, and hypoxia (Bush, 1995; Sanders et al., 1999). In turn, the increased [Ca 2 ϩ ] cyt triggers many signal transduction pathways, including the regulation of enzyme activity, ion channel activity, and gene expression, which results in diverse cellular responses (Bush, 1995). In addition to its role as a second messenger, Ca 2 ϩ also is important in regulating the processing of proteins in secretory pathways (Rudolph et al., 1989). Thus, cells require carefully regulated transport systems to control [Ca 2 ϩ ] in the cytoplasm and endomembrane compartments. Influx of Ca 2 ϩ to the cytosol occurs as a "downhill" transport through Ca 2 ϩ channels (Sanders et al., 1999). In contrast, the efflux of Ca 2 ϩ from the cytosol is mediated by two active Ca 2 ϩ transporters-Ca 2 ϩ pumps and Ca 2 ϩ /H ϩ antiporters-which are powered by ATP hydrolysis and proton motive force, respectively (Bush, 1995). In plants, Ca 2 ϩ -ATPases are believed to be a major Ca 2 ϩ transporter for the endoplasmic reticulum (ER), Golgi apparatus, vacuole, plastid inner membrane, and plasma membrane (Sander...

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“…Structural information has been derived from examination of calmodulin bound to peptides (Ikura et al, 1992;Meador et al, 1992Meador et al, , 1993 and by analysis of structural modifications of calmodulin on its activation of target enzymes (Craig et al, 1987;Persechini et al, 1989;Weber et al, 1989;Kosk-Kosicka and Bzdega, 1991 ;Cao et al, 1993 light-chain kinase (Ikura et al, 1992;Meador et al, 1992) and Ca*'/calmodulin-dependent protein kinase I1 (Meador et al, 1993). The crystal structure of calmodulin bound to Ca2'-ATPase is not known, but the complex appears to adopt a more extended conformation than the globular shape seen with the other peptides (Kataoka et al, 1991). In this work we used an indirect approach to examine the role of specific sequences of calmodulin in target interactions.…”

Section: Discussionmentioning

confidence: 99%

Analysis of Phosphorylation and Mutation of Tyrosine Residues of Calmodulin on Its Activation of the Erythrocyte Ca²⁺‐transporting ATPase

Sacks

López

et al. 1996

European Journal of Biochemistry

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The role played by the phosphorylation sites of calmodulin on its ability to activate the human erythrocyte Ca' +-transporting ATPase (Ca" -ATPase) was evaluated. Phosphorylation of mammalian calmodulin on serine/threonine residues by casein kinase TI decreased its affinity for Ca'+-ATPase by twofold. In contrast, tyrosine phosphorylation of mammalian calmodulin by the insulin-receptor kinase did not significantly alter calmodulin-stimulated Ca'? -ATPase activity. Two variant calmodulins, each containing only one tyrosine residue (the second Tyr is replaced by Phe) were also examined: [F138]calmodulin, a mutant containing tyrosine at position 99, and wheat germ calinodulin which has tyrosine at position 139. The concentrations of [FI 38 Jcalmodulin and wheat germ calmodulin required for half-maximal activation of Ca' ' -,4TPase were tenfold and fourfold higher, respectively, than mammalian calmodulin.Phosphorylation at Tyr99 of [F138]calmodulin shifted its affinity for Ca'+-ATPase towards that of mammalian calmodulin. However, phosphorylation at Tyrl39 of wheat germ calmodulin had essentially no effect on its interaction with Ca'+-ATPase. Thus, all of the observed effects of both phosphorylation and substitution of residues of calmodulin are on its affinity for Ca*+-ATPase, not on V,,,.,,. The effects are dependent on the site of phosphate incorporation. Replacement of tyrosine with phenylalanine has a larger effect than phosphorylation of tyrosine, suggesting that the observed functional alterations reflect a seco'ndary conformational change in the C-terminal half of calmodulin, the region that is itnportant in its activation of Ca2+-ATPase.

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Small-angle x-ray scattering study of calmodulin bound to two peptides corresponding to parts of the calmodulin-binding domain of the plasma membrane calcium pump

Cited by 107 publications

References 28 publications

Tryptophan 1093 Is Largely Responsible for the Slow Off Rate of Calmodulin from Plasma Membrane Ca2+ Pump 4b

Tryptophan 1093 Is Largely Responsible for the Slow Off Rate of Calmodulin from Plasma Membrane Ca2+ Pump 4b

Identification of a Calmodulin-Regulated Soybean Ca²⁺-ATPase (SCA1) That Is Located in the Plasma Membrane

Analysis of Phosphorylation and Mutation of Tyrosine Residues of Calmodulin on Its Activation of the Erythrocyte Ca²⁺‐transporting ATPase

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Small-angle x-ray scattering study of calmodulin bound to two peptides corresponding to parts of the calmodulin-binding domain of the plasma membrane calcium pump

Cited by 107 publications

References 28 publications

Tryptophan 1093 Is Largely Responsible for the Slow Off Rate of Calmodulin from Plasma Membrane Ca2+ Pump 4b

Tryptophan 1093 Is Largely Responsible for the Slow Off Rate of Calmodulin from Plasma Membrane Ca2+ Pump 4b

Identification of a Calmodulin-Regulated Soybean Ca2+-ATPase (SCA1) That Is Located in the Plasma Membrane

Analysis of Phosphorylation and Mutation of Tyrosine Residues of Calmodulin on Its Activation of the Erythrocyte Ca2+‐transporting ATPase

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Identification of a Calmodulin-Regulated Soybean Ca²⁺-ATPase (SCA1) That Is Located in the Plasma Membrane

Analysis of Phosphorylation and Mutation of Tyrosine Residues of Calmodulin on Its Activation of the Erythrocyte Ca²⁺‐transporting ATPase