Polygalacturonases Release Cell-Wall-bound Proteins

Abstract

Puified polygaacturonases from two fungi released proteins from wai fractions prepared from three plant species. Peroxidase activity was associated with the proteins released from the ceil wails, and several of the protein fractions released contained hydroxyproline. Ceilulase, purifled free of pectic enzyme activity, was ineffective in releasing ceil wail proteins. Specific inhibition of endopolygalacturonase activity prevented release of the proteins.Endopolygalacturonases and endopectate lyases, enzymes that degrade the galacturonate polymers of plant cell walls, cause cell death when applied to excised tissues (3,4,13,20), leaves and cuttings (5, 13), and intact plants (14). Peroxide appears to be involved in the endoPG2-induced damage to cotton leaf tissue (13). Peroxidases are associated with plant cell walls (2,16,17, 24), and are released from isolated cell walls by purified endopectate lyase (3) and purified endoPG (22). Release of peroxidases from cell walls may be important in the endoPG-induced damage of some plant tissues. In addition, the release of proteins by pectic enzymes is important to our understanding of the localization of proteins in plant cell walls and could be a means of obtaining cell wall proteins in a relatively native state. We have studied the release of wall proteins using cell walls from three plant species and purified pectic enzymes from two fungi. MATERIALS AND METHODSCell Wail Preparation. A modification of Barnett's technique (2) was used to prepare cell walls from potato tuber tissues, carrot xylem parenchyma, and etiolated cotton hypocotyls. Potato tubers and carrots were purchased locally. Cotton hypocotyls were grown in the dark for 8 days in Jiffy-Mix (Jiffy Products of America, West Chicago, Ill.) at 26 to 29 C. Excised tissues were homogenized in a chilled Sorvall Omni-Mixer for 2 min in 0.1 M sodium phosphate, pH 7.4, containing 1% (v/v) 1-octanol. Homogenized material was rinsed on Miracloth with several liters of ice-cold deionized H20, suspended in 100 ml of the phosphate buffer containing 2 M NaCl, and allowed to stand for at least 30 min at 4 C. The cold water rinse was repeated, and the osmotically shocked material was passed through a prechilled French pressure cell at 10,000 to 12,000 p.

Investigation and optimization of a novel enzymatic approach for the isolation of proteins from potato pulp

“…The increase of temperature seems to have more effect on the yield than the PGase 371 units. A previous study confirms the necessity in hydrolysing the galacturonide segments to 372 release cell-wall proteins which was previously conducted with polygalacturonase purified from 373 Verticillium alboatrum(Strand et al, 1976).374 Like protein yield, extracted patatin was also affected by the interaction of units of PGase 375 and temperature (x 1 x 4 , Table 3 and Fig. 3B).…”

Release of Protein from Normal and Mutant Tomato Cell Walls

“…The release of protein through PG action has previously been shown to occur with various plant species (12,19), with enzymic activity also being shown (12,19,21). Salt extraction of tomato cell walls resulted in a protein fraction displaying a restricted range of metabolic activities.…”

“…A number of enzymes present in whole cell concentrates and having high activity (9) were either absent or possibly not released from the CWP under our experimental conditions. On balance, it seems unlikely that PG has the ability to release the hydroxyproline-rich protein from cell walls (12,19).…”

“…But as well as an expected breakdown of pectic material in cell walls derived from a number of plant tissues (5,13), substantial quantities of protein (12,19) are also released.…”

Localization of the Ethylene-synthesizing System in Apple Tissue

“…It is now apparent that plasma membrane and cell wall may share proteins and glycoproteins (13,25,27,29,33,34) and hormone-binding receptors or components (4,12,20,28); also the involvement of plant hormones, viz. IAA, gibberellins, cytokinins, and ABA with ethylene production has been pointed out (8,14,15).…”