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A defective signal peptide in the maize high-lysine mutant floury 2.

ABSTRACT: The maize floury 2 (fl2) mutation enhances the lysine content of the grain, but the soft texture of the endosperm makes it unsuitable for commercial production. The mutant phenotype is linked with the appearance of a 24-kDa alpha-zein protein and increased synthesis of binding protein, both of which are associated with irregularly shaped protein bodies. We have cloned the gene encoding the 24-kDa protein and show that it is expressed as a 22-kDa alpha-zein with an uncleaved signal peptide. Comparison of the deduced N-terminal amino acid sequence of the 24-kDa alpha-zein protein with other alpha-zeins revealed an alanine to valine substitution at the C-terminal position of the signal peptide, a histidine insertion within the seventh alpha-helical repeat, and an alanine to threonine substitution with the same alpha-helical repeat of the protein. Structural defects associated with this alpha-zein explain many of the phenotypic effects of the fl2 mutation.

SUBMITTER: Coleman CE

PROVIDER: S-EPMC41422 | biostudies-other | 1995 Jul

REPOSITORIES: biostudies-other

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A defective signal peptide in the maize high-lysine mutant floury 2.

Coleman C E CE Lopes M A MA Gillikin J W JW Boston R S RS Larkins B A BA

Proceedings of the National Academy of Sciences of the United States of America 19950701 15

The maize floury 2 (fl2) mutation enhances the lysine content of the grain, but the soft texture of the endosperm makes it unsuitable for commercial production. The mutant phenotype is linked with the appearance of a 24-kDa alpha-zein protein and increased synthesis of binding protein, both of which are associated with irregularly shaped protein bodies. We have cloned the gene encoding the 24-kDa protein and show that it is expressed as a 22-kDa alpha-zein with an uncleaved signal peptide. Compa ...[more]

PMID: 7624327

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