Identification and molecular characterization of novel peroxidase with structural protein-like properties.
Elicitor treatment or mechanical damage to Scutellaria baicalensis Georgi (skullcap plants) callus causes an immediate insolubilization of a 36-kDa protein into cell walls. The 36-kDa protein was identified as peroxidase 1 by analysis of its internal amino acid sequence and by immunoblotting using affinity-purified anti-peroxidase 1. Insolubilized peroxidase 1 is cross-linked to lignin through covalent bonds, and the cross-linking is catalyzed in the presence of H(2)O(2) by peroxidase 1 itself. The properties of insolubilized peroxidase 1 resemble those of defense-related structural proteins (extensins and proline-rich proteins) cross-linked to cell wall. Although the isozymes peroxidases 2 and 3 have enzyme activities similar to peroxidase 1, they are not insolubilized by stress treatment. Molecular characterization established that peroxidase 1 contains regions characteristic of structural proteins, but peroxidases 2 and 3 do not have such regions. These results suggest that among the three isozymes, only peroxidase 1 has a structural protein-like function as well as an enzymatic function.
Morimoto
S
S
Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan. morimoto@shoyaku.phar.kyushu-u.ac.jp
Tateishi
N
N
Inuyama
M
M
Taura
F
F
Tanaka
H
H
Shoyama
Y
Y
D000595:Amino Acid Sequence; D001483:Base Sequence; D002473:Cell Wall / Q000201:enzymology; D003001:Cloning, Molecular; D018076:DNA, Complementary; D007700:Kinetics; D008969:Molecular Sequence Data; D009195:Peroxidase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010944:Plants / Q000201:enzymology; D017386:Sequence Homology, Amino Acid; D012995:Solubility
D018076:DNA, Complementary; D009195:Peroxidase