PLANT PHYSIOLOGY , Vol 113, Issue 3 863-871, Copyright © 1997 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
A Cysteine Endopeptidase Isolated from Castor Bean Endosperm Microbodies Processes the Glyoxysomal Malate Dehydrogenase Precursor Protein
C. Gietl, B. Wimmer, J. Adamec and F. Kalousek
Institute of Botany, Technical University of Munich, Arcisstrasse 16, D-80333 Munich, Germany (C.G., B.W.)
A plant cysteine endopeptidase with a molecular mass of 35 kD was purified
from microbodies of germinating castor bean (Ricinus communis) endosperm by
virtue of its capacity to specifically process the glyoxysomal malate
dehydrogenase precursor protein to the mature subunit in vitro. Processing
of the glyoxysomal malate dehydrogenase precursor occurs sequentially in
three steps, the first intermediate resulting from cleavage after
arginine-13 within the presequence and the second from cleavage after
arginine-33. The endopeptidase is unable to remove the presequences of
prethiolases from rape (Brassica napus) glyoxysomes and rat peroxisomes at
the expected cleavage site. Protein sequence analysis of N-terminal and
internal peptides revealed high identity to the mature papain-type cysteine
endopeptidases from cotyledons of germinating mung bean (Vigna mungo) and
French bean (Phaseolus vulgaris) seeds. These endopeptidases are
synthesized with an extended pre-/prosequence at the N terminus and have
been considered to be processed in the endoplasmic reticulum and targeted
to protein-storing vacuoles.
