Phosphoenolpyruvate Carboxylase from Spinach Leaf Tissue

Mukerji, S.; Yang, Shui-Bo

doi:10.1104/pp.53.6.829

Cited by 29 publications

(10 citation statements)

References 4 publications

(5 reference statements)

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“…2), an observation typical for C3 plants. The (14), and a similar enzyme may be present in P. milioides. The absence of a curvilinear response curve in soybean indicates that either the Km(HC03-) of soybean PEP carboxylase is higher than the Km (CO2) of RuDP carboxylase and Km(HC03-) of P. milioides PEP carboxylase, or soybean PEP carboxylase is largely inactive in the light.…”

Section: Discussionmentioning

confidence: 88%

Differential Oxygen Response of Photosynthesis in Soybean and Panicum milioides

Keck

Ogren

1976

Plant Physiol.

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The carbon dioxide compensation concentration of Panicum milioides was less than that of soybean over the range of 15 to 35 C. In soybean (Glycine max IL.] Merr. cv. Wayne), the compensation concentration was directly proportional to 02 concentration. In P. milioides, the compensation concentration was near zero up to 10% 02 and then increased linearly with higher 02, although the slope of the response was less than that in soybean. Leaf extracts of P. milioldes contained 3-fold higher phosphoenolpyruvate carboxylase activity than soybean leaf extracts. Oxygen inhibition of photosynthesis and carboxylation efficiency was less in P. milioides than that observed in soybean. The affinity of P. millioides ribulose-1,5-di-P carboxylase for CO2 appeared to be slightly greater than that of soybean. (30 C day/20 C night, 14 hr photoperiod, 550 ,ueinstein m-2 sec-1) and subirrigated with modified Hoagland solution. Seeds of P. milioides (P.I. 310042) were germinated on a paper wick and, after 10 to 14 days, transplanted into vermiculite. Subsequent growth conditions were identical to those for soybean and maize. Experiments were conducted with the most recent fully expanded soybean trifoliate leaf, 10-to 14-day-old maize leaves, and 4-to 5-week-old leaves of P. milioides.Gas Exchange Measurements. Net photosynthesis and F were measured with excised leaves at 25 C. In Figure 1, experiments were done at 15, 20, 25, 30, and 35 C. The closed system used in these measurements has been described elsewhere (13). In experiments using variable O2 concentrations, desired gas mixtures were made from cylinders of N2, 02, and 1 % CO2 in N2.Carboxylation efficiency was calculated as described previously (13).Enzyme Measurements. Crude leaf extracts were prepared by grinding about 200 mg (fresh weight) of leaf tissue in a TenBroeck homogenizer for 2 min in ice, in a grinding medium of 50 mM tris-Cl, pH 8, 10 mM MgC92, 5 mm dithiothreitol, 5 mM isoascorbate, and 0.1 mm, EDTA. The homogenizer was rinsed with additional grinding medium and added to the extract to bring the final volume to 10 ml. The crude extract was assayed for RuDP carboxylase (13) and PEP carboxylase (5) activities.Partially purified RuDP carboxylase, for the determination of Km and-Ki values, was prepared as follows. About 1 g (fresh weight) of leaf tissue was ground in a TenBroeck homogenizer in ice, in 5 mM K phosphate, pH 7.6, 5 mm mercaptoethanol, 0.1 mM EDTA, and 6 % PVP. After grinding, the extract was centrifuged at 18,000g for 10 min, and the pellet discarded. Cold, saturated (NH4)2SO4 solution was slowly added to the supernatant to give 35 % saturation. After stirring for 20 min in ice bath, the suspension was centrifuged at 10,000g for 10 min, and the pellet discarded. Saturated (NH4)2SO4 was added to bring the supernatant to 50% saturation. After stirring for 20 min, the suspension was centrifuged at 18,000g for 10 min, and the supernatant discarded. The pellet was dissolved in 1 ml of 25 mM tris-Cl, pH 8, 10

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Section: Discussionmentioning

confidence: 88%

Differential Oxygen Response of Photosynthesis in Soybean and Panicum milioides

Keck

Ogren

1976

Plant Physiol.

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“…While PEPC is normally thought to have a very high affinity for inorganic carbon compared with Rubisco, the PEPC K m (HCO 3 2 ) has been reported to be between 25 and 100 mM for C 4 plants (O'Leary, 1982;Bauwe, 1986;Hatch and Burnell, 1990) and between 100 and 200 mM for C 3 plants (Mukerji and Yang, 1974;Sato et al, 1988). Since the dissolved CO 2 concentration in the cytoplasm of C 3 plants is expected to be about 12 mM at 400 mL L 21 CO 2 and 25°C, the HCO 3 2 concentration at equilibrium would be close to 60 mM assuming a cytoplasmic pH of 7 and a CO 2 -to-HCO 3 2 pKa of 6. reported K m (HCO 3 2 ) for PEPC.…”

Section: Discussionmentioning

confidence: 99%

The Cytoplasmic Carbonic Anhydrases βCA2 and βCA4 Are Required for Optimal Plant Growth at Low CO₂

et al. 2016

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Carbonic anhydrases (CAs) are zinc metalloenzymes that interconvert CO 2 and HCO 3 2 . In plants, both a-and b-type CAs are present. We hypothesize that cytoplasmic bCAs are required to modulate inorganic carbon forms needed in leaf cells for carbonrequiring reactions such as photosynthesis and amino acid biosynthesis. In this report, we present evidence that bCA2 and bCA4 are the two most abundant cytoplasmic CAs in Arabidopsis (Arabidopsis thaliana) leaves. Previously, bCA4 was reported to be localized to the plasma membrane, but here, we show that two forms of bCA4 are expressed in a tissue-specific manner and that the two proteins encoded by bCA4 localize to two different regions of the cell. Comparing transfer DNA knockout lines with wild-type plants, there was no reduction in the growth rates of the single mutants, bca2 and bca4. However, the growth rate of the double mutant, bca2bca4, was reduced significantly when grown at 200 mL L 21 CO 2 . The reduction in growth of the double mutant was not linked to a reduction in photosynthetic rate. The amino acid content of leaves from the double mutant showed marked reduction in aspartate when compared with the wild type and the single mutants. This suggests the cytoplasmic CAs play an important but not previously appreciated role in amino acid biosynthesis.Carbonic anhydrases (CAs) are zinc metalloenzymes that catalyze the interconversion of CO 2 and HCO 3 2 . Flowering plants possess members of the aCA, bCA, and gCA families. While all three CA families contain zinc, they clearly have evolved independently (Hewett-Emmett and Tashian, 1996). Most aCAs are monomeric, although there are notable exceptions (Whittington et al., 2001;Hilvo et al., 2008;Suzuki et al., 2010Suzuki et al., , 2011Cuesta-Seijo et al., 2011). The aCA active site contains a single zinc molecule coordinated by three His residues and a water molecule (Liljas et al., 1972). bCAs also contain a zinc active site, although the coordinating molecules are two Cys residues, a His, and a water molecule (Bracey et al., 1994). The active unit of the bCA is a dimer where the active site is located at the interface of the two monomers (Kimber and Pai, 2000). In contrast, gCAs are trimers that have their active site zinc ion situated at the interface of two subunits coordinated by His residues from both subunits (Kisker et al., 1996;Iverson et al., 2000).In Arabidopsis (Arabidopsis thaliana), there are three gCA proteins and two g-like proteins that interact to form an extra structure of complex I of the mitochondrial electron transport chain (Perales et al., 2004;Sunderhaus et al., 2006). Although not active in vitro, gCA has been shown to bind inorganic carbon (Martin et al., 2009), affect complex I levels, plant growth, and gas-exchange rates when deleted (Perales et al., 2004;Soto et al., 2015), and cause plant sterility when ectopically overexpressed ). Arabidopsis has eight aCA genes, but only aCA1, aCA2, and aCA3 appear to be expressed in leaf tissue. aCA1 has been reported to be localized to the c...

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“…The Km values for the three Panicum species are higher (0.4 to 0.8 mM) (Table I). Km values greater than 0.10 mM HC03-also have been reported in other species (4,13,15); thus, Km values for HC03-are not consistently low in green tissues. When one considers the variation in the data, the Km values determined for the enzyme from P. laxum and P. milioides are only slightly higher than those for the P. prionitis enzyme (Table I).…”

Section: Resultsmentioning

confidence: 70%

Comparative Characterization of Phosphoenolpyruvate Carboxylase in C₃, C₄, and C₃-C₄ Intermediate Panicum Species

Holaday¹,

Black²

1981

Plant Physiol.

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(8). Glucose-6-P increases the activity of the partially purified enzyme from C4 and CAM species (4, 21-23) at saturating substrate and Mg2" concentrations, whereas glycine activates only the enzyme from monocot C4 species (16,22).Recently, Panicum milioides, a grass with photorespiratory activity intermediate between C3 and C4 plants (2), was reported to possess a C4 photosynthesis system with PEP carboxylase responsible for 24% of the initial CO2 assimilation (18). However, earlier photosynthesis work in our laboratory using room air failed to detect 14C in organic acids, therefore indicating a low in vivo PEP carboxylase activity (5, 9), as found in C3 species. But PEP carboxylase is present in C3-C4 intermediate species at levels above those in C3 plants (9). The genus Panicum contains C3, C4, and C3-C4 intermediate species. The study presented here was initiated to determine whether PEP carboxylase in the intermediate Panicum species has properties similar to those of either the C3 or the C4 enzyme or if the enzyme in intermediate Panicum species has unique properties which indicate a role in the reduction of photorespiration in C3-C4 intermediate plants. , and Zea mays (L.) (C4). These Panicum species are members of the subgroup Laxa (7) and possess photosynthetic characteristics of the types indicated in parentheses above (2,3,11,12). MATERIALS AND METHODSEnzyme Assays. Except for the effector studies, the PEP carboxylase assays were performed using whole-leafextracts prepared by grinding 0.1 g fresh weight of leaf material as previously described (23). Aliquots were taken for Chl deternination (1) before centrifugation. PEP carboxylase activity was determined (unless otherwise specified) at 30 C by the 4C incorporation method of Van et al. (23). The assay solutions contained, in 1 ml: 50 mm Tris-HCl (pH 8.3), 10 mM MgCl2, 5 mm DTT, 10 mM NaH'4C03 (0.5 ,uCi/,mol), 5 mM PEP, and plant extract.In the kinetic studies, the concentration of HCO3-or PEP was varied. For the HC03-analyses, a "CO2-free" Tris-HCl (

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Phosphoenolpyruvate Carboxylase from Spinach Leaf Tissue

Cited by 29 publications

References 4 publications

Differential Oxygen Response of Photosynthesis in Soybean and Panicum milioides

Differential Oxygen Response of Photosynthesis in Soybean and Panicum milioides

The Cytoplasmic Carbonic Anhydrases βCA2 and βCA4 Are Required for Optimal Plant Growth at Low CO₂

Comparative Characterization of Phosphoenolpyruvate Carboxylase in C₃, C₄, and C₃-C₄ Intermediate Panicum Species

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Phosphoenolpyruvate Carboxylase from Spinach Leaf Tissue

Cited by 29 publications

References 4 publications

Differential Oxygen Response of Photosynthesis in Soybean and Panicum milioides

Differential Oxygen Response of Photosynthesis in Soybean and Panicum milioides

The Cytoplasmic Carbonic Anhydrases βCA2 and βCA4 Are Required for Optimal Plant Growth at Low CO2

Comparative Characterization of Phosphoenolpyruvate Carboxylase in C3, C4, and C3-C4 Intermediate Panicum Species

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The Cytoplasmic Carbonic Anhydrases βCA2 and βCA4 Are Required for Optimal Plant Growth at Low CO₂

Comparative Characterization of Phosphoenolpyruvate Carboxylase in C₃, C₄, and C₃-C₄ Intermediate Panicum Species