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A K Mattoo

Publications and source records attributed to A K Mattoo.

At least 37 records · Page 2Linked to original sources
PubMed1992

Accumulation of wound-inducible ACC synthase transcript in tomato fruit is inhibited by salicylic acid and polyamines.

Regulation of wound-inducible 1-aminocyclopropane-1-carboxylic acid (ACC) synthase expression was studied in tomato fruit (Lycopersicon esculentum cv. Pik-Red). A 70 base oligonucleotide probe homologous to published ACC synthase cDNA sequences was successfully used to identify and analyze regulation of a wound-inducible transcript. The 1.8 kb ACC synthase transcript increased upon wounding the fruit as well as during fruit ripening. Salicylic acid, an inhibitor of wound-responsive genes in tomato, inhibited the wound-induced accumulation of the ACC synthase transcript. Further, polyamines (putrescine, spermidine and spermine) that have anti-senescence properties and have been shown to inhibit the development of ACC synthase activity, inhibited the accumulation of the wound-inducible ACC synthase transcript. The inhibition by spermine was greater than that caused by putrescine or spermidine. The transcript level of a wound-repressible glycine-rich protein gene and that of the constitutively expressed rRNA were not affected as markedly by either salicylic acid or polyamines. These data suggest that salicylic acid and polyamines may specifically regulate ethylene biosynthesis at the level of ACC synthase transcript accumulation.

Base Sequence↗
PubMed1991

Wound-regulated accumulation of specific transcripts in tomato fruit: interactions with fruit development, ethylene and light.

Regulation of three cDNA clones (pT52, pT53, and pT58) was analyzed in terms of wounding alone and wounding in conjunction with developmental and environmental cues (ripening, ethylene, and light) in tomato fruit tissue. The pT52-specific transcript level is induced by wounding in early-red and red stage fruit and by ethylene. The pT58-specific transcript level is also induced by wounding and ethylene in early-red stage fruit but is not induced by wounding in red fruit. The pT53-specific transcript level is repressed by wounding in early-red and red stage fruit. Like the pT52- and pT58-specific transcripts, the pT53-specific transcript is induced by ethylene. Furthermore, the level of the pT52-specific transcript is regulated by light. Analysis of unwounded tissue showed that the abundance of each cDNA-specific transcript changes during fruit ripening and that each of the transcripts is present in other plant organs as well. This analysis provides information about the interactions between developmental and environmental factors affecting these genes.

DNA↗
PubMed1991

Translational modification of an 18 kilodalton polypeptide by spermidine in rice cell suspension cultures.

When rice (Oryza sativa) cell suspension cultures are grown in the presence of [terminal methylenes-(3)H]spermidine, label is incorporated in a single polypeptide with a molecular mass of 18 kilodaltons on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Preincubation of cell cultures with polyamine biosynthesis inhibitors difluoromethylarginine and difluoromethylornithine, resulted in increased incorporation of the label into the 18 kilodalton polypeptide. In cells in which protein synthesis was arrested by cycloheximide, no label was detected in the 18 kilodalton polypeptide, suggesting a requirement for de novo protein synthesis.

Journal Article↗
PubMed1990

A novel metabolic form of the 32 kDa-D1 protein in the grana-localized reaction center of photosystem II.

Two forms of the 32 kDa-D1 reaction center protein of photosystem II (PSII), having slightly different mobilities on denaturing polyacrylamide gels, have been resolved in Spirodela oligorrhiza, Glycine max L., Gossypium hirsutum L., Triticum aestivum L., and Zea mays L. The protein band with faster mobility is identified as the 32 kDa-D1 protein, and the less mobile band as a novel form, designated 32*. The two forms are structurally similar based on immunological and partial proteolytic tests. 32* is associated exclusively with the grana and is present in the PSII reaction center. Temporally, 32* appears several hours after the translocation of newly synthesized and processed 32 kDa-D1 protein from the stroma lamellae to the grana. Formation of the 32* is strictly light-dependent under physiological light intensities and correlates with a reciprocal loss of the 32-kDa form. Light induced formation of 32* is inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea but is not coupled to linear electron transport.

2,4-Dinitrophenol↗
PubMed1989

Visualization of acid phosphatase activity on nitrocellulose filters following electroblotting of polyacrylamide gels.

A method for visualizing acid phosphatase isoenzymes by activity staining on nitrocellulose filters after electroblotting of proteins fractionated on nondenaturing polyacrylamide gels is described. Reproducible results were obtained when 25 mM Tris-192 mM glycine was used as the transfer buffer instead of 0.7% acetic acid, 50 mM sodium acetate, pH 4, or 0.14 M acetic acid--0.35 M beta-alanine, pH 4.3. Dot-blot analysis of banana fruit extracts on nitrocellulose filters revealed that a minimum of 5 x 10(-3) units (nmol p-nitrophenyl phosphate hydrolyzed g-1.h-1) of acid phosphatase activity can be detected. This method can be suitable for screening a large number of biological samples for monitoring acid phosphatase activity.

Acid Phosphatase↗
PubMed1989

Identification of covalently bound fatty acids on acylated proteins immobilized on nitrocellulose paper.

A general method for identification of fatty acids covalently bound to acylated proteins following their electrophoretic transfer onto nitrocellulose paper is described. As demonstrated for [3H]palmitoylated RAS1 protein of Saccharomyces cerevisiae and the acylated acyl carrier protein of Spirodela oligorrhiza, this procedure alleviates the need for elution of proteins from polyacrylamide gel slices. Fatty acid ligands of such proteins are hydrolyzed directly from their immobilized state on the nitrocellulose paper, then derivatized with p-nitrophenacyl bromide, and finally resolved by reversed-phase high-performance liquid chromatography. The amount of acylated protein required for identification of acyl groups is minimized compared to that required for more conventional approaches by coupling a radioactive flow detector with the HPLC system.

Acylation↗
PubMed1989

Separate photosensitizers mediate degradation of the 32-kDa photosystem II reaction center protein in the visible and UV spectral regions.

A component of the photosystem II reaction center, the 32-kDa protein, is rapidly turned over in the light. The mechanism of its light-dependent metabolism is largely unknown. We quantified the rate of 32-kDa protein degradation over a broad spectral range (UV, visible, and far red). The quantum yield for degradation was highest in the UVB (280-320 nm) region. Spectral evidence demonstrates two distinctly different photosensitizers for 32-kDa protein degradation. The data implicate the bulk photosynthetic pigments (primarily chlorophyll) in the visible and far red regions, and plastoquinone (in one or more of its redox states) in the UV region. A significant portion of 32-kDa protein degradation in sunlight is attributed to UVB irradiance.

Chlorophyll↗
PubMed1989

Rapid in Vivo Acylation of Acyl Carrier Protein with Exogenous Fatty Acids in Spirodela oligorrhiza.

Posttranslational acylation of several chloroplast proteins with palmitic acid was recently demonstrated in Spirodela oligorrhiza (AK Mattoo, M Edelman [1987] Proc Natl Acad Sci USA 84: 1497-1501). We have now identified an in vivo acylated, soluble protein having an apparent M(r) of 10 kilodaltons on sodium dodecyl sulfate-polyacrylamide gel electrophoresis as an acylated form of acyl carrier protein (ACP). This 10-kilodalton protein is present in low abundance, and its acylation is light-stimulated. Turnover of the acyl moiety but not the apo-protein is rapid in the light. The acylated 10-kilodalton protein coelectrophoreses with in vitro synthesized palmitoyl-acyl carrier protein and is immunoprecipitated from soluble extracts with an antibody raised against spinach ACP. Cerulenin, an inhibitor of beta-ketoacyl-ACP synthetase, inhibited in vivo acylation of Spirodela ACP. Cell-free extracts of Spirodela plants were able to catalyze the transfer of palmitate from palmitoyl-CoA to ACP, suggesting the existence in higher plants of a pathway for acylation of ACP that involves transacylation from acyl-CoA.

Journal Article↗
PubMed1989

Changes in Sugars, Enzymic Activities and Acid Phosphatase Isoenzyme Profiles of Bananas Ripened in Air or Stored in 2.5% O(2) with and without Ethylene.

This study investigates the effect of 2.5% O(2), both alone and in combination with ethylene, on respiration, sugar accumulation and activities of pectin methylesterase and acid phosphatase during ripening of bananas (Musa paradisiaca sapientum). In addition, the changes in the phosphatase isoenzyme profiles are also analyzed. Low oxygen diminished respiration and slowed down the accumulation of sugars and development of the yellow color. Furthermore, low O(2) prevented the rise in acid phosphatase activities and this suppression was not reversed by the inclusion of 100 microliters per liter ethylene in 2.5% O(2) atmosphere. Gel electrophoresis of both the soluble and particulate cell-free fractions under nondenaturing conditions revealed the presence of 8 and 9 isoenzymes in the soluble and particulate fractions, respectively. Low O(2) suppressed the appearance of all isoenzymes, and the addition of 500 microliters per liter ethylene to the low oxygen atmosphere did not reverse this effect. Similarly, the decline in pectin methylesterase that was observed in air-ripened fruits was prevented by 2.5% O(2) alone and in combination with 500 microliters per liter ethylene.

Journal Article↗
PubMed1989

Hydrolytic Enzyme Activities and Protein Pattern of Avocado Fruit Ripened in Air and in Low Oxygen, with and without Ethylene.

The effect of 2.5% O(2) atmosphere with and without ethylene on the activities of hydrolytic enzymes associated with cell walls, and total protein profile during ripening of avocado fruits (Persea americana Mill., cv Hass) were investigated. The low 2.5% O(2) atmosphere prevented the rise in the activities of cellulase, polygalacturonase, and acid phosphatase in avocado fruits whose ripening was initiated with ethylene. Addition of 100 microliters per liter ethylene to low O(2) atmosphere did not alter these suppressive effects of 2.5% O(2). Furthermore, 2.5% O(2) atmosphere delayed the development of a number of polypeptides that appear during ripening of avocado fruits while at the same time new polypeptides accumulated. The composition of the extraction buffer and its pH greatly affected the recovery of cellulase activity and its total immunoreactive protein.

Journal Article↗
PubMed1989

Distribution of Thylakoid Proteins between Stromal and Granal Lamellae in Spirodela : Dual Location of Photosystem II Components.

We have quantified the lateral distribution of 12 thylakoid proteins of Spirodela oligorrhiza by immunoblot analysis of detergent-derived granal and stromal lamellae. The immunological, ultrastructural, cytochemical, and biophysical measurements each indicated the expected overall separation of photosystem II (PSII) and photosystem I (PSI) components; however, certain proteins were not completely localized to one lamellar fraction. The apoproteins of the light harvesting chlorophyll a/b complex, subunit 1 of PSI and the components of the PSII reaction center (the 32 kilodalton, D2, and cytochrome b(559) proteins) were dually located between granal and stromal lamellae. Proteins associated exclusively with one of the membrane types were: in granal lamellae, the 43 and 51 kilodalton PSII proteins, and in stromal lamellae, the alpha and beta subunits of the proton ATPase.

Journal Article↗
PubMed1988

Identification of a unique isoform of 1-aminocyclopropane-1-carboxylic acid synthase by monoclonal antibody.

1-Aminocyclopropane-1-carboxylic acid (ACC) synthase (EC 4.4.1.14) is a key enzyme regulating ethylene biosynthesis in higher plants. A monoclonal antibody (mAb T20C) that immunoprecipitates the ACC synthase activity from tomato pericarp tissue extracts revealed that mAb T20C immunodecorates an approximately 67-kDa polypeptide. On isoelectric focusing gels, ACC synthase activity in cell-free preparations was resolved into three distinct activity peaks with pI values 5.3, 7, and 9. mAb T20C specifically recognized the pI 7 form of the enzyme on electrophoretic transfer (Western) blots. When analyzed by sodium dodecyl sulfate gel electrophoresis under reducing conditions, the eluted pI 7 form was confirmed to migrate as a polypeptide of 67 kDa. The 67-kDa pI 7 isoform is a previously undescribed form of ACC synthase.

Journal Article↗
PubMed1987

Identification of a primary in vivo degradation product of the rapidly-turning-over 32 kd protein of photosystem II.

The 32 kd photosystem II protein of plant chloroplasts is rapidly turned over in the light. The initial events in the degradation of the 32 kd protein were studied. A 23.5 kd breakdown product was identified in Spirodela oligorrhiza membranes using immunological analysis. The 23.5 kd polypeptide was shown to be derived from the amino-terminal portion of the 32 kd protein using partial proteolytic fingerprinting. An in vivo precursor--product relationship between the 32 kd protein and the 23.5 kd polypeptide was kinetically demonstrated by radiolabeling and pulse-chase experiments. The cleavage site yielding the 23.5 kd polypeptide was localized to a functionally active region (between helices IV and V) of the 32 kd protein. We propose that an alpha-helix-destabilizing 'degradation' sequence, bordered by arginine residues 225 and 238, is involved in the formation of the 23.5 kd polypeptide.

Chlorophyll↗
PubMed1987

Intramembrane translocation and posttranslational palmitoylation of the chloroplast 32-kDa herbicide-binding protein.

The 32-kDa herbicide-binding protein, a component of photosystem II, is synthesized as a membrane-associated 33.5-kDa precursor within the chloroplast. We show that membrane attachment of the precursor and processing to the 32-kDa form occur in the unstacked stromal lamellae. Once processed, the 32-kDa protein translocates, within the thylakoids, to the topologically distinct stacked granal lamellae. Posttranslational palmitoylation of the processed 32-kDa protein is also shown to occur. This modification takes place in a membrane-protected domain and is mainly confined to the protein assembled in the granal lamellae, where functional photosystem II centers are concentrated.

Acylation↗
PubMed1987

Degradation of the 32 kD Herbicide Binding Protein in Far Red Light.

White light (400-700 nanometers) supports the activity of photosystem I (PSI) and photosystem II while far red light (>/=700 nanometers) supports PSI almost exclusively. In intact fronds of Spirodela oligorrhiza, turnover of the 32 kilodaltons herbicide binding protein is stimulated under both these light conditions, although not in the dark or at wavelengths >730 nanometers. As is the case in white light, the far red light induced degradation of the protein is inhibited by DCMU. The means by which far red light operates is unclear. Hypotheses considered include: PSI activated proteolysis, PSI-induced formation of semiquinone anions, and PSI-generated free radicals.

Journal Article↗