Identification of a single‐copy gene encoding a Type I chlorophyll a/b‐binding polypeptide of photosystem I in Arabidopsis thaliana

Abstract

We have isolated and sequenced cDNA and genomic clones from Arabidopsis thaliana which specify a 241 residue protein with 84% sequence identity to a photosystem I Type I chlorophyll a/b‐binding (CAB) protein from tomato. The open reading frame is interrupted by three introns which are found at equivalent positions as the corresponding introns in the tomato gene. Comparison to the amino acid sequence of other CAB proteins confirms that all CAB proteins share two regions of very high similarity. However, near the N‐terminus and between the conserved regions this light‐harvesting complex I (LHCI) protein, as other LHCI proteins from other plant species, has sequence motifs which appear to be PSI‐specific. Restriction analysis of genomic DNA shows that the Arabidopsis protein is encoded by a single‐copy gene.