The maize floury1 gene encodes a novel endoplasmic reticulum protein involved in zein protein body formation.
The maize (Zea mays) floury1 (fl1) mutant was first reported almost 100 years ago, but its molecular identity has remained unknown. We report the cloning of Fl1, which encodes a novel zein protein body membrane protein with three predicted transmembrane domains and a C-terminal plant-specific domain of unknown function (DUF593). In wild-type endosperm, the FL1 protein accumulates at a high level during the period of zein synthesis and protein body development and declines to a low level at kernel maturity. Immunogold labeling showed that FL1 resides in the endoplasmic reticulum surrounding the protein body. Zein protein bodies in fl1 mutants are of normal size, shape, and abundance. However, mutant protein bodies ectopically accumulate 22-kD alpha-zeins in the gamma-zein-rich periphery and center of the core, rather than their normal discrete location in a ring at outer edge of the core. The 19-kD alpha-zein is uniformly distributed throughout the core in wild-type protein bodies, and this distribution is unaffected in fl1 mutants. Pairwise yeast two-hybrid experiments showed that FL1 DUF593 interacts with the 22-kD alpha-zein. Results of these studies suggest that FL1 participates in protein body formation by facilitating the localization of 22-kD alpha-zein and that this is essential for the formation of vitreous endosperm.
Holding
David R
DR
Department of Plant Sciences, University of Arizona, Tucson, Arizona, 85721, USA.
Otegui
Marisa S
MS
Li
Bailin
B
Meeley
Robert B
RB
Dam
Thao
T
Hunter
Brenda G
BG
Jung
Rudolf
R
Larkins
Brian A
BA
D000483:Alleles; D000595:Amino Acid Sequence; D017124:Conserved Sequence; D004721:Endoplasmic Reticulum / Q000378:metabolism* / Q000648:ultrastructure; D018506:Gene Expression Regulation, Plant; D007425:Intracellular Membranes / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics*; D011485:Protein Binding; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000166:cytology / Q000648:ultrastructure; D020798:Two-Hybrid System Techniques; D003313:Zea mays / Q000166:cytology / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D015028:Zein / Q000378:metabolism* / Q000648:ultrastructure
D008565:Membrane Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; D015028:Zein
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