Glucanase activity in coleoptiles of Avena

Heyn, A. N. J.

doi:10.1016/0003-9861(69)90387-7

Cited by 51 publications

(17 citation statements)

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“…Such involvement might be in agreement with findings that certain antibiotics inhibit cell elongation and plasticization of the cell wall (4)(5)(6) and that protein synthesis, as well as synthesis of DNA and RNA, is a requirement for cell elongation (7)(8)(9)(10)(11)(12). In that study, the presence of enzymes in elongating coleoptiles was investigated, and several glucanases were found to be associated with the cell walls (13).…”

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Molecular basis of auxin-regulated extension growth and role of dextranase

Heyn

1981

Proc. Natl. Acad. Sci. U.S.A.

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The first step in the extension growth ofthe plant cell is a process in which the cell wall becomes ductile or plastic, after which the actual enlargement takes place passively under the influence of turgor. The nature of this process has not been explained, although much research has been carried out concerning it. In the present report, it is shown that a specific enzyme, which is identical or nearly so with dextranase (a-1,6-D-glucan 6-glucanohydrolase, EC 3.2.1.11) and is associated with the cell walls of growing coleoptiles, plays a prominent role in this process. The action ofthis enzyme is dependent on the level ofgrowth hormone, auxin, in the tissue. Under its action, certain cell wall components are broken down to yield arabinose and glucose. These sugars are also released during autolysis ofcell wall material. The molecular linkages broken in the process are probably the arabinogalactan crosslinks of the hemicellulose matrix, which are the main constituents of the wall containing arabinose. This is substantiated by the finding that dextranase can break down arabinan and compounds containing arabinose chains with the release of arabinose, just as in the action of the enzyme on the wall. The breaking of these crosslinks will impart the necessary plasticity to the wall for cell extension to occur.The essential step in auxin-regulated extension growth (elongation) of the plant cell is plasticization ("loosening") of the cell wall. Thereafter, the cell wall may be irreversibly extended under the influence of the turgor to bring about the actual enlargement of the cell (1-3). The nature of this physical modification of the wall and the underlying process have remained unknown until now.In 1968, I undertook a study of the possible involvement of enzymes in this process. Such involvement might be in agreement with findings that certain antibiotics inhibit cell elongation and plasticization of the cell wall (4-6) and that protein synthesis, as well as synthesis of DNA and RNA, is a requirement for cell elongation (7-12). In that study, the presence of enzymes in elongating coleoptiles was investigated, and several glucanases were found to be associated with the cell walls (13).In an effort to screen out the enzyme actually involved in the process of the modification of the cell wall under the influence of the hormone, the effect of the hormone concentration in the tissue on the activity of the enzymes, at optimal pH range, was studied. The activity ofonly one glucanase was found to depend on the auxin level in the tissue and to be higher at higher auxin concentration. This enzyme is dextranase (a-1,6-D-glucan 6-glucanohydrolase, EC 3.2. 1.11) (14,15).Whether this outstanding behavior is due to a special, direct sensitivity of the enzyme to the hormone or to a more complicated situation such as the interplay of more than one enzyme need not be considered at this point. The special behavior of this enzyme, however, made it first choice for being investigated as the possible "master" enzyme in the process...

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confidence: 86%

Molecular basis of auxin-regulated extension growth and role of dextranase

Heyn

1981

Proc. Natl. Acad. Sci. U.S.A.

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confidence: 99%

“…Our specific interest has been the latter possibility. There are numerous reports of wall "bound" enzymes and of their apparent ability to break down wall polysaccharides (10,11,15,17 vance is the work of Masuda and co-workers on the participation of glucanohydrolase enzymes in oat coleoptile elongation (19,24,27).The purpose of this research was to determine if enzymes capable of cleaving glycosidic bonds are present in hypocotyl tissue and how their activities vary during hypocotyl development. Particular attention was devoted to changes in enzymatic activity during the period immediately preceding maximal elongation and to correlating enzyme activities with observed changes in cell wall composition.…”

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confidence: 99%

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Relation of Glycosidases to Bean Hypocotyl Growth

Nevins

1970

Plant Physiol.

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The enzymes ,3-glucosidase, a-glucosidase, 3-galactosidase, a-galactosidase, and 3-xylosidase were detected in Phaseolus vulgaris L. var. Red Kidney bean hypocotyl tissue throughout the first 13 days of development with p-nitrophenyl glycosides as substrates. Activities of all enzymes except B-glucosidase declined as a function of increasing tissue age. In contrast, B-glucosidase activity increased rapidly 3 days after imbibition to a maximal activity at 5 days and then subsided to one-third the maximum by day 7.This activity peak immnediately preceded the logarithmic phase of hypocotyl growth. This enzyme is strongly associated with cell walls during extraction, suggesting that it is wall-bound in situ. Various polysaccharide substrates were used to evaluate the specificity of this enzyme.Plant cell walls play an important role in mediating physiological events in plant development and are specifically involved in the mechanism of cell elongation. Tissues with the potential to elongate undergo changes in wall compliance, i.e., an increase in extensibility, as measured by various types of stress-strain analyzers, subsequent to the application of growth-promoting hormones (6-9, 20, 26). To account for such changes in the physical characteristics of the cell wall, one may postulate an alteration or alterations of the chemical nature of the wall structure prior to any major change in mechanical extensibility. The precise nature of such a wall alteration is unknown. It is known, however, that the cell wall is composed largely of noncellulosic polysaccharides prior to the onset of the most rapid elongation phase of growth (2, 21). During this period the relative amount of cellulose is generally rather low (2). As the tissue elongates, the relative amount of noncellulosic polysaccharide declines, and during this period changes in individual monosaccharides of the polymer fraction occur at different rates (21). These dramatic changes in polysaccharide composition reflect, in part, complex changes in the chemical constituency (bonding) of the wall which might in some physiochemical sense affect wall compliance values. The observed changes in wall composition may result from net synthesis or net removal of polysaccharide segments containing specific monosaccharides or groups of monosaccharides. Our specific interest has been the latter possibility. There are numerous reports of wall "bound" enzymes and of their apparent ability to break down wall polysaccharides (10,11,15,17 vance is the work of Masuda and co-workers on the participation of glucanohydrolase enzymes in oat coleoptile elongation (19,24,27).The purpose of this research was to determine if enzymes capable of cleaving glycosidic bonds are present in hypocotyl tissue and how their activities vary during hypocotyl development. Particular attention was devoted to changes in enzymatic activity during the period immediately preceding maximal elongation and to correlating enzyme activities with observed changes in cell wall composition. METHODS AND MATERIAL...

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“…Among these are two reports of ,B-1 ,3-glucanase activity in suspension-cultured plant cells (10,18). Recently, Heyn reported a number of glucanase activities in Avena coleoptiles, including a very active 0-1,3-glucanase (11). Masuda has presented evidence that cell wall-degrading enzymes, especially B-1,3-glucanase, may play an important role in auxin-induced growth (19,20,28,29).…”

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confidence: 99%

The Involvement of Glycosidases in the Cell Wall Metabolism of Suspension-cultured Acer pseudoplatanus Cells

Keegstra

Albersheim

1970

Plant Physiol.

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Several glycosidases have been isolated from suspensioncultured sycamore (Acer pseudoplatanus) cells. These include an a-galactosidase, an a-mannosidase, a f-N-acetylglucosaminidase, a ,B-glucosidase, and two ,3-galactosidases.The pH optimum of each of these enzymes was determined. Glycosidases have been reported in a variety of bacteria, fungi, animals, and higher plants. In plants, glycosidases have long been known to be present in seeds and storage material (1,2,4,8,9,15,17,(24)(25)(26)(27). Recently, there has been considerable interest in these glycosidases. One of the major reasons for the increased interest in these enzymes has been their usefulness as tools for studying the structure of oligo-and polysaccharides. Li has studied an a-mannosidase from jack bean meal and has used it to study a-mannosides present in glycoproteins (15-17). Agrawal and Bahl have studied the glycosidases from the cotyledons of Phaseolus vulgaris (1, 4). They have used these enzymes to study the structure of the saccharide portion of a glycoprotein hormone (3). An a-galactosidase from coffee beans has been used to study various galactomannans (7).Further interest in these enzymes stems from the possibility that they may be involved in growth of microbial and plant cells. ,-1 , 3-Glucanases have been reported to be widespread in higher plants (6). Among these are two reports of ,B-1 ,3-glucanase activity in suspension-cultured plant cells (10,18 growth (19,20,28,29). Cell wall-degrading enzymes have been reported to be present in crude preparations of cell walls (12)(13)(14). These findings suggest that glycosidases partially degrade cell walls and, in so doing, facilitate cell growth.In this report we describe a number of glycosidases of sycamore cells (Acer pseudoplatanus) grown in suspension culture. Some of the glycosidases are found associated with the cell walls. The activity of some of these hydrolytic enzymes is greater during log phase growth than prior to or after the growth period of these suspension-cultured cells.MATERIAL AND METHODS Sycamore cells (A. pseudoplatanus) were grown on M-6 media as described earlier (5) except that 20 g/liter of sucrose was used rather than 40 g/liter.For the growth experiments, cells were grown in 2800-ml Fernbach flasks with a three-way stopcock attached near the bottom. The stopcock was sterilized by passing 70% ethanol through it before and after each use. Cells were withdrawn while the culture was agitated by a magnetic stirrer. Representative samples of the cell population could be obtained in this manner.The cells were collected on a coarse scintered glass funnel. The collected cells were washed with 5 volumes of 0.5 M potassium phosphate, pH 7.0, and the wash solution was saved. The washed cells were suspended in additional phosphate buffer (1.0 ml of buffer for each g of cells) and disrupted by forcing the suspension through a French pressure cell at 2,000 p.s.i. The resulting preparation was centrifuged for 60 min at 40,000g.The enzymes in the 0.5 M wash from the whole ...

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Glucanase activity in coleoptiles of Avena

Cited by 51 publications

References 43 publications

Molecular basis of auxin-regulated extension growth and role of dextranase

Molecular basis of auxin-regulated extension growth and role of dextranase

Relation of Glycosidases to Bean Hypocotyl Growth

The Involvement of Glycosidases in the Cell Wall Metabolism of Suspension-cultured Acer pseudoplatanus Cells

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