Regulation of 2-Carboxyarabinitol 1-Phosphatase

Holbrook, Gabriel P.; Galasinski, Scott C.; Salvucci, Michael E.

doi:10.1104/pp.97.3.894

Cited by 30 publications

(31 citation statements)

References 21 publications

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“…Previous studies have shown that purified leaf and recombinant activase are extremely heat-labile if incubated in the absence of ATP (Robinson and Portis, 1989;Holbrook et al, 1991;Eckardt and Portis, 1997). Our results corroborated these findings, because we observed inactivation of both forms upon exposure to relatively moderate temperatures (i.e.…”

Section: Discussionsupporting

confidence: 82%

The Two Forms of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Activase Differ in Sensitivity to Elevated Temperature

1997

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Ribulose-l,5-bisphosphate carboxylase/oxygenase activase often consists of two polypeptides that arise from alternative splicing of pre-mRNA. I n this study recombinant versions of the spinach (Spinacea oleracea L.) 45-and 41-kD forms of activase were analyzed for their response to temperature. The temperature optimum for ATP hydrolysis by the 45-kD form was 45"C, approximately 13°C higher than the 41 -kD form. When the two forms were mixed, the temperature response of the hybrid enzyme was similar to the 45-kD form. I n the absence of adenine nucleotide, preincubation of either activase form at temperatures above 25°C inactivated ATPase activity. Adenosine 5'-(y-thio)triphosphate, but not ADP, significantly enhanced the thermostability of the 45-kD form but was much less effective for the 41-kD form. lntrinsic fluorescence showed that the adenosine 5'-(y-thio)triphosphate-induced subunit aggregation was lost at a much lower temperature for the 41-kD than for the 45-kD form. However, the two activase forms were equally susceptible to limited proteolysis after heat treatment. The results indicate that (a) the 45-kD form is more thermostable than, and confers increased thermal stability to, the 41 -kD form, and (b) a loss of subunit interactions, rather than enzyme denaturation, appears to be the initial cause of temperature inactivation of activase.Zielinski, 1991a). In spinach the 45-and 41-kD activase polypeptides are identical except for 37 additional amino acids on the C-terminal end of the 45-kD form. Both the 45-and the 41-kD forms of spinach activase catalyze ATP hydrolysis, as well as activate Rubisco (Shen et al., 1991). However, aside from relatively minor differences in ATP binding (Shen et al., 1991), there is no information about other functional differences between the two forms of activase.In this paper we report the effect of elevated temperature on the 45-and 41-kD forms of recombinant spinach activase. Our results show that the two forms differ significantly in thermal stability and, when mixed, the thermal stability of the hybrid enzyme is similar to the 45-kD form. The greater thermal stability of the 45-kD form appears to be related to tighter subunit association. MATERIALS AND METHODSCloning and lsolation of the Long a n d Short Forms of Rubisco ActivaseClones encoding the 45-and 41-kD forms of spinach (Spinacea oleracea L.) Rubisco activase (pPLEX1.9 and Rubisco activase is a chloroplastic enzyme that regulates pPLEX1.6), described by Werneke et al. (1989) and Shen et the activity of Rubisco in a light-dependent manner (Salal. (1991) Salvucci and Ogren, 1996). Once freed of these plasmids were used for expression of recombinant activase compounds, Rubisco can be activated by spontaneous car- (van de Loo and Salvucci, 1996). Recombinant Rubisco bamylation with CO, (Lorimer and Miziorko, 1980). activase was purified from the cells, as described by SalIn most of the plant species that have been examined, vucci and Klein (1994), with the modifications noted by van Rubisco activase is composed...

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Section: Discussionsupporting

confidence: 82%

The Two Forms of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Activase Differ in Sensitivity to Elevated Temperature

1997

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“…DCMU did not affect the rate of [14C]CAlP accumulation in the dark, but did greatly reduce the rate of its degradation in the light, a result comparable to a previous observation made using leaf discs (18). Although CAlP phosphatase activity in vitro is inhibited about 50% by Pi (7), the lack of any observed mannose effect on CAlP metabolism (Table II) indicates that Pi may not normally have any regulatory function, contrary to a previous suggestion (7,15). The inhibition of CAlP accumulation in the dark by DTT and NaF were quite unexpected (Table II).…”

Section: Discussioncontrasting

confidence: 55%

Metabolism of 2′-Carboxyarabinitol in Leaves

Moore

Seemann²

1992

Plant Physiol.

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“…Evidence was presented that heat stress perturbed the structural properties of activase. In support of this hypothesis, the activity of isolated activase has been shown to be extremely sensitive to high temperature (Robinson and Portis, 1989;Holbrook et al, 1991;Crafts-Brandner et al, 1997;. Crafts-Brandner et al (1997) presented evidence that high temperature inhibited activase by disrupting subunit interactions.…”

mentioning

confidence: 77%

“…Isolated activase is extremely heat labile (Robinson and Portis, 1989;Holbrook et al, 1991;Crafts-Brandner et al, 1997;, and the different polypeptide forms of activase differ in their sensitivity to inactivation by high temperature (Crafts-Brandner et al, 1997). The basis of thermal sensitivity appears to be disruption of subunit interactions that are necessary for activity (CraftsBrandner et al, 1997).…”

Section: Discussionmentioning

confidence: 99%

Inhibition and Acclimation of Photosynthesis to Heat Stress Is Closely Correlated with Activation of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase

1999

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Increasing the leaf temperature of intact cotton (Gossypium hirsutum L.) and wheat (Triticum aestivum L.) plants caused a progressive decline in the light-saturated CO 2 -exchange rate (CER). CER was more sensitive to increased leaf temperature in wheat than in cotton, and both species demonstrated photosynthetic acclimation when leaf temperature was increased gradually. Inhibition of CER was not a consequence of stomatal closure, as indicated by a positive relationship between leaf temperature and transpiration. The activation state of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), which is regulated by Rubisco activase, was closely correlated with temperature-induced changes in CER. Nonphotochemical chlorophyll fluorescence quenching increased with leaf temperature in a manner consistent with inhibited CER and Rubisco activation. Both nonphotochemical fluorescence quenching and Rubisco activation were more sensitive to heat stress than the maximum quantum yield of photochemistry of photosystem II. Heat stress led to decreased 3-phosphoglyceric acid content and increased ribulose-1,5-bisphosphate content, which is indicative of inhibited metabolite flow through Rubisco. We conclude that heat stress inhibited CER primarily by decreasing the activation state of Rubisco via inhibition of Rubisco activase. Although Rubisco activation was more closely correlated with CER than the maximum quantum yield of photochemistry of photosystem II, both processes could be acclimated to heat stress by gradually increasing the leaf temperature.Inhibition of photosynthetic CO 2 fixation by high temperature has been documented in many plant species (for review, see Berry and Bjö rkman, 1980). Several components of the photosynthetic apparatus and associated metabolic processes are heat labile. For example, PSII is thermally labile (Havaux, 1993;Havaux and Tardy, 1996) but can be acclimated to heat stress (Havaux, 1993). Recent evidence indicates that a chloroplast-localized heat-shock protein protects PSII from damage at high temperature (Heckathorn et al., 1998). Export of photoassimilate is another metabolic process that is sensitive to inhibition by high temperature. Jiao and Grodzinski (1996) reported that heat stress inhibited assimilate export to a greater degree than net photosynthesis. Inhibition was especially apparent at a high atmospheric CO 2 concentration at which assimilate export, but not net photosynthesis, was inhibited by heat stress. However, in a similar study using a different plant species (Leonardos et al., 1996), heat stress under a high atmospheric CO 2 concentration inhibited net photosynthesis but not assimilate export. Thus, the sensitivity of assimilate export to inhibition by heat stress may differ among plant species and/or associated environmental conditions.Based on Chl fluorescence analysis, Bilger et al. (1987) reported that Calvin cycle activity was sensitive to rapid heat-stress treatments. Previous reports have documented that Rubisco activation is a primary site of inhibition (Wei...

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Regulation of 2-Carboxyarabinitol 1-Phosphatase

Cited by 30 publications

References 21 publications

The Two Forms of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Activase Differ in Sensitivity to Elevated Temperature

The Two Forms of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Activase Differ in Sensitivity to Elevated Temperature

Metabolism of 2′-Carboxyarabinitol in Leaves

Inhibition and Acclimation of Photosynthesis to Heat Stress Is Closely Correlated with Activation of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase

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