PLANT PHYSIOLOGY , Vol 105, Issue 1 233-241, Copyright © 1994 by American Society of Plant Biologists
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MOLECULAR BIOLOGY AND GENE REGULATION |
Brassica napus Plastid and Mitochondrial Chaperonin-60 Proteins Contain Multiple Distinct Polypeptides
L. P. Cloney, D. R. Bekkaoui, G. L. Feist, W. S. Lane and S. M. Hemmingsen
Plant Biotechnology Institute, National Research Council, 110 Gymnasium Place, Saskatoon, Saskatchewan, Canada S7N 0W9 (L.P.C., D.R.B., G.L.F., S.M.H.)
Plastid chaperonin-60 protein was purified to apparent homogeneity from
Brassica napus using a novel protocol. The purified protein, which migrated
as a single species by nondenaturing polyacrylamide gel electrophoresis,
contained four polypeptides: three variants of p60cpn60[alpha] and
p60cpn60[beta]. Partial amino acid sequence determination demonstrated that
each variant of p60cpn60[alpha] is a distinct translation product. During
this study, additional chaperonin-60 proteins were purified. These
proteins, which were free from contaminating plastid chaperonin-60, were
separated into at least two high molecular weight species that were
resolved only by nondenaturing polyacrylamide gel electrophoresis. These
proteins contained three 60-kD polypeptides. Two of these polypeptides were
recognized by existing antisera, whereas the third was not. Partial amino
acid sequence data revealed that each of these, including the
immunologically distinct polypeptide, is a chaperonin-60 subunit of
putative mitochondrial origin. The behavior of chaperonin-60 proteins
during blue A Dyematrex chromatography suggests that this matrix may be
generally useful for the identification of chaperonin-60 proteins.
