cDNA, amino acid and carbohydrate sequence of barley seed-specific peroxidase BP 1.
The major peroxidase of barley seed BP 1 was characterized. Previous studies showed a low carbohydrate content, low specific activity and tissue-specific expression, and suggested that this basic peroxidase could be particularly useful in the elucidation of the structure-function relationship and in the study of the biological roles of plant peroxidases (S.K. Rasmussen, K.G. Welinder and J. Hejgaard (1991) Plant Mol Biol 16: 317-327). A cDNA library was prepared from mRNA isolated from seeds 15 days after flowering. Full-length clones were obtained and showed 3' end length variants, a G+C content of 69% in the translated region, a 90% G or C preference in the wobble position of the codons and a typical signal peptide sequence. N-terminal amino acid sequencing and sequence analysis of tryptic peptides verified 98% of the sequence of the mature BP 1 which contains 309 amino acid residues. BP 1 is the first characterized plant peroxidase which is not blocked by pyroglutamate. BP 1 polymorphism was observed. BP 1 is less than 50% identical to other plant peroxidases which, taken together with its developmentally dependent expression in the endosperm 15-20 days after flowering, suggests a unique biological role of this enzyme. The barley peroxidase is processed at the C-terminus and might be targeted to the vacuole. The single site of glycosylation is located near the C-terminus in the N-glycosylation sequon -Asn-Cys-Ser- in which Cys forms part of a disulphide bridge. The major glycan is a typical plant modified-type structure, Man alpha 1-6(Xyl beta 1-2)Man beta 1-4GlcNAc beta 1-4(Fuc alpha 1-3)GlcNAc. The BP 1 gene was RFLP-mapped on barley chromosome 3, and we propose Prx5 as the name for this new peroxidase locus.
Environmental Science and Technology Department, Risø National Laboratory, Roskilde, Denmark.
A
A
Johansson
S K
SK
Rasmussen
J E
JE
Harthill
K G
KG
Welinder
D000595:Amino Acid Sequence; D001483:Base Sequence; D002240:Carbohydrate Sequence; D003001:Cloning, Molecular; D001467:Hordeum / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D009195:Peroxidase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012150:Polymorphism, Restriction Fragment Length; D011499:Protein Processing, Post-Translational; D012639:Seeds / Q000201:enzymology* / Q000235:genetics
D009195:Peroxidase