A chlorophyll a/b-protein encoded by a gene containing an intron with characteristics of a transposable element

Abstract

We have sequenced a genomic subclone (pLg AB19/H5c) of Lemna gibba nuclear DNA containing a complete chlorophyll a/b protein coding region and 5' and 3' flanking nucleotides. The coding region contains an intron of 84 nucleotides that has features characteristic of a transposable element. Evidence from S1 nuclease mapping experiments is consistent with correct transcription and splicing of the AB19 or another closely related intron-containing gene. The encoded precursor polypeptide of 264 amino acid residues has a predicted Mr of 28,327. Approximately 35 N-terminal residues are cleaved from this protein to form the mature apoprotein. We have used theoretical considerations of protein structure to propose an experimentally testable model of the structure of this protein in thylakoid membranes.