Regulation of Catalase Activity in Leaves of Nicotiana sylvestris by High CO₂

Abstract

The effect of high CO2 (1% C02/21% 02) on the activity of specific forms of catalase (CAT-1, -2, and -3) (EA Havir, NA McHale [1987] Plant Physiol 84: 450-455) in seedling leaves of tobacco (Nicotiana sylvestris, Nicotiana tabacum) was examined. In high C02, total catalase activity decreased by 50% in the first 2 days, followed by a more gradual decline in the next 4 days. The loss of total activity resulted primarily from a decrease in CAT-1 catalase. In contrast, the activity of CAT-3 catalase, a form with enhanced peroxidatic activity, increased 3-fold in high CO2 relative to aiontrols after 4 days. Short-term exposure to high CO2 indicated that the 50% loss of total activity occurs in the first 12 hours. Catalase levels increased to normal within 12 hours after seedlings were retumed to air. When seedlings were transferred to air after prolonged exposure to high CO2 (13 days), the levels of CAT-1 catalase were partially restored while CAT-3 remained at its elevated level. Levels of superoxide dismutase activity and those of several peroxisomal enzymes were not affected by high CO2. Total catalase levels did not decline when seedlings were exposed to atmospheres of 0.04% C02/5% 02 or 0.04% C02/1% 02, indicating that regulation of catalase in high CO2 is not related directly to suppression of photorespiration. Antibodies prepared against CAT-1 catalase from N. tabacum reacted strongly against CAT-1 catalase from both N. sylvestris and N. tabacum but not against CAT-3 catalase from either species. This observation, along with the rapid changes in CAT-I and the much slower changes in CAT-3 suggest that one form is not directly derived from the other. concentration (5, 19) have been shown to influence catalase activity in mature plants. For example, Fair et al. (5) demonstrated that catalase activity was suppressed when barley was grown in 1 to 5% CO2 and in 2% 02. Other peroxisomal enzymes were suppressed also and thus the effect in barley may be generally on peroxisomal turnover. In cases where catalase regulation is independent of peroxisomal turnover (e.g. Refs. 4, 6, and this paper) the mechanism of regulation has not been determined but could be the result of changes in rates of synthesis, degradation, or by covalent modification of the protein. The determination by Eising et al. (3) that the sharp decline in catalase activity in greening sunflower cotyledons was due to the formation of an inactive but largely intact protein molecule may be pertinent to studies of environmentally related changes in catalase activity.We previously showed that catalase activity in leaves of tobacco seedlings was distributed among several forms, one ofwhich had enhanced peroxidatic activity and that there was a change in distribution with time of development (l1). Furthermore, transfer of the seedlings to 1% C02/2 1% 02 for 4 d reduced total catalase activity by about 50% and altered the distribution ofthe activities. Here we show that the decline in catalase in high CO2 is very rapid and results primarily from the los...

Enhanced-Peroxidatic Activity in Specific Catalase Isozymes of Tobacco, Barley, and Maize

“…In maize, EP-CAT is the product of the Cat3 gene (14,15). In other plant species such as tobacco (4,5) and barley the evidence for separate genetic control is indirect. In barley, reduction of the level of T-CAT catalase in the CAT(-) mutant or in dark-grown wild-type does not affect the EP-CAT form.…”

“…These results suggest that this catalase isozyme is under separate genetic control in barley. This may also be the case in tobacco where the catalase isozyme with enhanced peroxidatic activity is an immunologically distinct protein (EA Havir, NA McHale [1989] Plant Physiol 89: 952-957). …”

“…3-5, 8, 9, 15) are known but it has been generally assumed that all forms of the enzyme exhibit the same catalytic properties. However, recently we demonstrated that in tobacco and spinach leaves there are two forms of catalase, distinguishable by their ratios of peroxidatic/catalatic activity (4,5). In tobacco the peroxidatic activity was enhanced 30-to 50-fold in the form of catalase, designated by its order of elution from a chromatofocusing column, as CAT-3.…”

“…CAT-3 were controlled separately (4,5). These included (a) the different time frames during development for expression of activity, (b) the different responses to C02-enrichment, and (c) the lack of cross-reactivity of CAT-3 with the antibody raised against CAT-1 (4, 5).…”

Análise da resposta antioxidativa de células in vitro de fumo (Nicotiana tabacum cv BY-2) submetidas ao metal pesado níquel

“…A Fe-SOD é rara em plantas, sendo encontrada em arabidopsis, com a função de catalisar a produção de H 2 O 2 formado durante a β-oxidação de ácidos graxos e nos peroxissomos das folhas, durante a fotorrespiração, transformando o glicolato em glioxilato (KLIEBENSTEIN et al, 1998;HAVIR;McHALE, 1989;GRATÃO, 2003).…”