A Thapsigargin-Sensitive Ca2+ Pump Is Present in the Pea Golgi Apparatus Membrane

Ordenes, Viviana R.; Reyes, Francisca; Wolff, Daniel; Orellana, Ariel

doi:10.1104/pp.002055

Cited by 41 publications

(25 citation statements)

References 35 publications

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“…17 These results contrast with data obtained in terrestrial plants where the ER-calciumATPase is not inhibited by thapsigargin, with the exception of a heavy metal/ calcium ATPase detected in the Golgi apparatus of pea seedlings 15 and a similar enzyme recently cloned in Arabidopsis thaliana. 16 In addition, time required to reach the maximal level of calcium depletion induced by thapsigargin i.e., 45 min is similar to that observed in mammalian cells, i.e., 30 min. 17 Thus, it is possible that marine algae ER-calcium ATPase share functional and structural properties with homologous enzymes in mammalian cells.…”

Section: Copper Induced the Activation Of Ryanodine-sensitive And Ip mentioning

confidence: 57%

Copper-induced calcium release from ER involves the activation of ryanodine-sensitive and IP3-sensitive channels inUlva compressa

González

Trebotich

Vergara

et al. 2010

Plant Signaling & Behavior

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T he marine alga Ulva compressa (Chlorophyta) showed a triphasic release of intracellular calcium with maximal levels at 2, 3 and 12 h and a biphasic accumulation of intracellular hydrogen peroxide with peaks at 3 and 12 h when cultivated with copper excess. Intracellular hydrogen peroxide originated exclusively in organelles. In this work, we analyzed the intracellular origin of calcium release and the type of calcium channels activated in response to copper excess. U. compressa was treated with thapsigargin, an inhibitor of endoplasmic reticulum (ER) calcium ATPase, ryanodine, an inhibitor of ryanodine-sensitive channels and xestospongin C, an inhibitor of inositol 1, 4, 5-triphosphate (IP 3 )-sensitive channels. Thapsigargin induced the depletion of calcium stored in ER at 75 min and completely inhibited calcium release at 2, 3 and 12 h of copper exposure indicating that calcium release originated in ER. In addition, ryanodine and xestospogin C inhibited calcium release at 2 and 3 h of copper exposure whereas the peak at 12 h was only inhibited by ryanodine. Thus, copper induced the activation of ryanodine-sensitive and IP 3 -sensitive calcium channels in ER of U. compressa.Plants showed common responses to biotic and abiotic stresses, mainly the accumulation of reactive oxygen species (ROS), in particular hydrogen peroxide, and the release of intracellular calcium.

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Section: Copper Induced the Activation Of Ryanodine-sensitive And Ip mentioning

confidence: 57%

Copper-induced calcium release from ER involves the activation of ryanodine-sensitive and IP3-sensitive channels inUlva compressa

González

Trebotich

Vergara

et al. 2010

Plant Signaling & Behavior

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“…As CPA at a concentration that induced [Ca 2+ ] cyt oscillations did not completely deplete the [Ca 2+ ] ER in this study, a CPA-insensitive Ca 2+ -ATPase in the ER might be related with the [Ca 2+ ] cyt oscillations. In addition, ECA3, another IIA-type Ca 2+ -ATPase from Arabidopsis, has been detected in the Golgi apparatus (Mills et al, 2008), and a CPA-sensitive Ca 2+ pump has been identified in both ER vesicles and the Golgi apparatus of Pisum sativum (Ordenes et al, 2002). Furthermore, vesicle accumulation independent of the ER was observed in the pollen tip of L. longiflorum (Parton et al, 2003;Bove et al, 2008).…”

Section: Dynamics In Arabidopsis Pollen Tubesmentioning

confidence: 83%

Fine-Tuning of the Cytoplasmic Ca2+ Concentration Is Essential for Pollen Tube Growth

Iwano

Entani²,

Shiba³

et al. 2009

Plant Physiology

170

147

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Pollen tube growth is crucial for the delivery of sperm cells to the ovule during flowering plant reproduction. Previous in vitro imaging of Lilium longiflorum and Nicotiana tabacum has shown that growing pollen tubes exhibit a tip-focused Ca2+ concentration ([Ca2+]) gradient and regular oscillations of the cytosolic [Ca2+] ([Ca2+]cyt) in the tip region. Whether this [Ca2+] gradient and/or [Ca2+]cyt oscillations are present as the tube grows through the stigma (in vivo condition), however, is still not clear. We monitored [Ca2+]cyt dynamics in pollen tubes under various conditions using Arabidopsis (Arabidopsis thaliana) and N. tabacum expressing yellow cameleon 3.60, a fluorescent calcium indicator with a large dynamic range. The tip-focused [Ca2+]cyt gradient was always observed in growing pollen tubes. Regular oscillations of the [Ca2+]cyt, however, were rarely identified in Arabidopsis or N. tabacum pollen tubes grown under the in vivo condition or in those placed in germination medium just after they had grown through a style (semi-in vivo condition). On the other hand, regular oscillations were observed in vitro in both growing and nongrowing pollen tubes, although the oscillation amplitude was 5-fold greater in the nongrowing pollen tubes compared with growing pollen tubes. These results suggested that a submicromolar [Ca2+]cyt in the tip region is essential for pollen tube growth, whereas a regular [Ca2+] oscillation is not. Next, we monitored [Ca2+] dynamics in the endoplasmic reticulum ([Ca2+]ER) in relation to Arabidopsis pollen tube growth using yellow cameleon 4.60, which has a lower affinity for Ca2+ compared with yellow cameleon 3.60. The [Ca2+]ER in pollen tubes grown under the semi-in vivo condition was between 100 and 500 μ m. In addition, cyclopiazonic acid, an inhibitor of ER-type Ca2+-ATPases, inhibited growth and decreased the [Ca2+]ER. Our observations suggest that the ER serves as one of the Ca2+ stores in the pollen tube and cyclopiazonic acid-sensitive Ca2+-ATPases in the ER are required for pollen tube growth.

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“…To determine the mechanisms underlying the importation of SAM into the Golgi, we purified Golgi vesicles from etiolated pea epicotyls, an experimental model plant that has been utilized previously to analyze the topology of enzymes involved in the biosynthesis of polysaccharides, as well as the transport of metabolites and ions (Muñ oz et al, 1996;Neckelmann and Orellana, 1998;Wulff et al, 2000;Sterling et al, 2001;Ordenes et al, 2002). We first determined the orientation of the catalytic domain of HGA-MT in our Golgi vesicle preparations by measuring its enzymatic activity in the presence of exogenous HGA as the acceptor for the methylation reaction.…”

Section: Resultsmentioning

confidence: 99%

The Import of S-Adenosylmethionine into the Golgi Apparatus Is Required for the Methylation of Homogalacturonan

Ibar

Orellana

2007

Plant Physiology

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S-adenosylmethionine (SAM) is the substrate used in the methylation of homogalacturonan (HGA) in the Golgi apparatus. SAM is synthesized in the cytosol, but it is not currently known how it is then transported into the Golgi. In this study, we find that HGA methyltransferase is present in Golgi-enriched fractions and that its catalytic domain faces the lumen of this organelle. This suggests that SAM must be imported into the Golgi. We performed uptake experiments using [methyl-14 C]SAM and found that SAM is incorporated into the Golgi vesicles, resulting in the methylation of polymers that are sensitive to pectinase and pectin methylesterase but not to proteases. To avoid detecting the transfer reaction, we also used [carboxyl-14 C]SAM, the uptake of which into Golgi vesicles was found to be sensitive to temperature, detergents, and osmotic changes, and to be saturable with a K m of 33 mM. Double-label uptake experiments using [methyl-3 H]SAM and [carboxyl-14 C]SAM also revealed a time-dependent increase in the 3 H to 14 C ratio, suggesting that upon transfer of the methyl group, the resulting S-adenosylhomocysteine is not accumulated in the Golgi. SAM incorporation was also found to be inhibited by S-adenosylhomocysteine, whereas UDP-GalA, UDP-GlcA, and acetyl-CoA had no effect. DIDS, a compound that inhibits nucleotide sugar transporters, also had little effect upon SAM incorporation. Interestingly, the combination of UDP-GalA 1 acetyl-CoA or UDP-GlcA 1 acetyl-CoA produced a slight increase in the uptake of SAM. These results support the idea that a SAM transporter is required for HGA biosynthesis.

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A Thapsigargin-Sensitive Ca2+ Pump Is Present in the Pea Golgi Apparatus Membrane

Cited by 41 publications

References 35 publications

Copper-induced calcium release from ER involves the activation of ryanodine-sensitive and IP3-sensitive channels inUlva compressa

Copper-induced calcium release from ER involves the activation of ryanodine-sensitive and IP3-sensitive channels inUlva compressa

Fine-Tuning of the Cytoplasmic Ca2+ Concentration Is Essential for Pollen Tube Growth

The Import of S-Adenosylmethionine into the Golgi Apparatus Is Required for the Methylation of Homogalacturonan

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