Identification and characterization of maize pathogenesis-related proteins. Four maize PR proteins are chitinases

Abstract

Eight pathogenesis-related proteins extractable at pH 2.8 were found to accumulate in maize leaves after mercuric chloride treatment or brome mosaic virus infection. These proteins were called PRm (pathogenesis-related maize) proteins. Seven PRm proteins were purified to homogeneity by preparative polyacrylamide gel electrophoresis and their amino acid compositions determined. Estimated molecular weights in SDS-containing gels were: PRm 1 14.2 kDa; Prm 2 16.5 kDa; PRm 3 and PRm 4 25 kDa; PRm 6b 30.5 kDa; PRm 6a 32 kDa; PRm 7 34.5 kDa. Antisera raised against either PRm 3 or PRm 4 reacted specifically each with PRm 3 or PRm 4. Antisera raised against PRm 6b reacted with PRm 6b as well as with PRm 6a and antisera against PRm 7 reacted with PRm 7 and PRm 5. Tobacco anti-PR 1b antisera reacted with maize PRm 2.Chitinase (poly[1,4-(N-acetyl-β-D-glucosamide)]glycanhydrolase, EC 3.2.1.14) activity was found for PRm 3, PRm 4, PRm 5, and PRm 7.

Xylanase, a Novel Elicitor of Pathogenesis-Related Proteins in Tobacco, Uses a Non-Ethylene Pathway for Induction

“…When the extracts of TMVtreated leaves were fractionated on denaturing SDS-PAGE the polypeptides of each PR protein class migrated at the following apparent molecular masses; PR-la, lb, lc at 19.5 kD; PR-2,N,O at 34 kD and PR-P,Q at 25 kD (Fig. 1B) (15,17,23). When all three antisera were applied simultaneously to the immunoblot ( Fig.…”

“…Specifically, the plant (1-3)-,6-glucanases, which are normally a part of the concerted response, were underrepresented. These experiments have revealed the presence of a novel ethylene-independent pathway for pathogenesis-related protein induction that is activated by xylanase.The de novo synthesis of PR2 proteins is a ubiquitous reaction of monocot (10,23,33) …”

“…The de novo synthesis of PR2 proteins is a ubiquitous reaction of monocot (10,23,33) and dicot plants (2,15) to pathogen attack. Originally characterized in relation to the hypersensitive response induced by TMV in tobacco plants containing the N gene (30), they appear to be part of a nonspecific host response to pathogens (22).…”

Purification and Characterization of Abundant Secreted Protein in Suspension-Cultured Pumpkin Cells

“…However, their biological function has largely remained elusive. Recently, three of them were shown to have 3-1,3-glucanase activity (15, 17), and four proteins have been identified as chitinases ( 17,19,22); it may catalyze the hydrolysis ofthe d-1,4 linkages of N-acetyl-D-glucosamine polymer chitin present in the cell walls of many fungi.…”

“…However, their biological function has largely remained elusive. Recently, three of them were shown to have 3-1,3-glucanase activity (15, 17), and four proteins have been identified as chitinases ( 17,19,22); it may catalyze the hydrolysis ofthe d-1,4 linkages of N-acetyl-D-glucosamine polymer chitin present in the cell walls of many fungi.When the culture medium in pumpkin cell suspension cultures was analyzed by SDS-PAGE, a major polypeptide band was observed at the position corresponding to Mr of 32,000 (10). In the present study, we have purified the abundant secreted protein (SP32) and prepared an antiserum against it.…”