Elicitor-inducib le Caffeoyl-Coenzyme A 3-0-Methyltransf erase fromPetroselinum crispum Cell Suspensions1 Purification, Partial Sequence, andAntigenicity

Parsley (Petroselinum crispum) cell cultures respond rapidly to treatment withfungal elicitor bytheaccumulation ofcoumarin phytoalexins intheculture fluid andbyincorporation offerulic esters intotheir cellwalls. S-Adenosyl-L-methionine:trans-caffeoyl-CoA 3-0-methyltransferase activity, specifically involved in theformation offerulic esters, isinduced under these conditions. Suchaninducible methyltransferase activity hasbeenfoundin plant cells ofvarious species. Themethyltransferase waspurified tohomogeneity fromparsley cells thathadbeentreated for12 hours withcrude cell wall elicitor fromPhytophthora megasperma f.sp.glycinea. Itconsists oftwoverysimilar oridentical subunits ofapproximately 24kilodaltons, whichareN-terminally blocked. Attempts togenerate antisera against thenative enzymeinrabbit ormousefailed, butanantiserum, cross-reactive inenzymelinked immunosorbent assays, wasraised inmousebyintraperitoneal injection oftheheat-denatured enzyme.Roughly 33%of theaminoacidsequence waselucidated bymicrosequencing of tryptic peptides ofthemethyltransferase. Theparsley enzyme mayberelated toadenine-specific methyltransferases known frombacterial sources. Antiserum generated inrabbit against a synthetic decapeptide, asinferred fromoneofthetryptic peptides andconjugated toovalbumin, specifically cross-reacted withthe methyltransferase protein inWestern blots developed after SDSpolyacrylamide electrophoresis. Thisserumdidnotreact, however, withnative parsley methyltransferase.