Construction of homo- and heteropolymers of plant ferritin subunits using an in vitro protein expression system.
Ferritin is a class of iron storage protein composed of 24 subunits. Although many studies on gene expression analyses of plant ferritin have been conducted, the functions and oligomeric assembly of plant ferritin subunits are still largely unknown. In order to characterize the ability to form multimeric protein shells and determine the iron incorporating activity, we produced ferritin homo- and heteropolymers by expressing four cDNAs of ferritin subunits from soybean, sfer1, sfer2, sfer3, and sfer4, using an in vitro protein expression system. Using SDS-PAGE analysis followed by Prussian blue stain, homopolymers of SFER1, SFER2, and SFER3, and heteropolymers of SFER1/SFER2 and SFER1/SFER3 were detected as assembled polymers with iron incorporating activity, whereas only a small amount of SFER4 related homo- and heteropolymer was detected, suggesting that the SFER4 was not competent for oligomeric assembly, unlike every other ferritin. We conclude that certain combinations of plant ferritin subunits can form heteropolymers and that their iron incorporating activities depend on the formation of multimeric protein.
Masuda
Taro
T
Laboratory of Food Quality Design and Development, Division of Agronomy and Horticultural Science, Graduate School of Agriculture, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan. masutaro@kais.kyoto-u.ac.jp
Goto
Fumiyuki
F
Yoshihara
Toshihiro
T
Ezure
Toru
T
Suzuki
Takashi
T
Kobayashi
Shinichiro
S
Shikata
Masamitsu
M
Utsumi
Shigeru
S
D000595:Amino Acid Sequence; D001704:Biopolymers / Q000378:metabolism*; D018076:DNA, Complementary; D005293:Ferritins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005822:Genetic Vectors; D006801:Humans; D007501:Iron / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015202:Protein Engineering; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D001704:Biopolymers; D018076:DNA, Complementary; D010940:Plant Proteins; D021122:Protein Subunits; D005293:Ferritins; D007501:Iron