Purification and characterization of chaperonin 60 and heat-shock protein 70 from chromoplasts of Narcissus pseudonarcissus.
In chromoplast differentiation during flower formation in Narcissus pseudonarcissus, the molecular chaperones chaperonin 60 (Cpn60; alpha and beta) and heat-shock protein 70 (Hsp70) greatly increase in abundance. Both were purified and shown to be present in a functional form in chromoplasts, indicating their requirement in the extensive structural rearrangements during the chloroplast-to-chromoplast transition. The purified proteins, sequenced N terminally and from internal peptides, showed strong homology to plastid Cpn60 and Hsp 70 representatives from other plant species. During chromoplast differentiation, the carotenoid biosynthetic pathway is strongly induced. The corresponding enzymes are all nuclear encoded and form a large, soluble, hetero-oligomeric protein complex after import but prior to their membrane attachment. By immunoprecipitations we have shown that the plastid Hsp70 is a structural constituent of a soluble entity also containing phytoene desaturase.
Bonk
M
M
Institut für Biologie II der Universität, Zellbiologie, Belgium.
Tadros
M
M
Vandekerckhove
J
J
Al-Babili
S
S
Beyer
P
P
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D018834:Chaperonin 60 / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D015388:Organelles / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D010944:Plants / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014357:Trypsin
D018834:Chaperonin 60; D018840:HSP70 Heat-Shock Proteins; D010446:Peptide Fragments; D014357:Trypsin; D000251:Adenosine Triphosphatases