A new family of plant antifungal proteins.
Plant seeds contain high concentrations of many antimicrobial proteins. These include chitinases, beta-1,3-glucanases, proteinase inhibitors, and ribosome-inactivating proteins. We recently reported the presence in corn seeds of zeamatin, a protein that has potent activity against a variety of fungi but has none of the above activities. Zeamatin is a 22-kDa protein that acts by causing membrane permeabilization Using a novel bioautography technique, we found similar antifungal proteins in the seeds of 6 of 12 plants examined. A polyclonal antiserum was raised against zeamatin and was used in immunoblots to confirm the presence of zeamatinlike proteins in these seeds. N-terminal amino acid sequencing was carried out on the antifungal proteins from corn, oats, sorghum, and wheat, and these sequences revealed considerable homology with each other. Interestingly, these N-terminal sequences are also similar to those of thaumatin, a pathogenesis-related protein from tobacco, and two salt stress-induced proteins. These results indicate that zeamatin is not unique but is a member of a previously unrecognized family of plant defense proteins that may include some species of pathogenesis-related proteins.
Vigers
A J
AJ
Department of Cellular and Structural Biology, University of Colorado Health Sciences Center, Denver 80262 U.S.A.
Roberts
W K
WK
Selitrennikoff
C P
CP
D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects; D003429:Cross Reactions; D004591:Electrophoresis, Polyacrylamide Gel; D015151:Immunoblotting; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D010944:Plants / Q000737:chemistry; D012639:Seeds / Q000737:chemistry; D014361:Trypsin Inhibitors
D000935:Antifungal Agents; D010940:Plant Proteins; D014361:Trypsin Inhibitors; C073468:zeamatin protein, Zea mays