Nucleotide sequence of a rice cDNA encoding a transkelotase-like protein homologous to the Arabidopsis CLA1gene product (Accession No. AF024512) (PGR 97-169)

Abstract

The Arabidopsis gene CLA1 is required for normal chloroplast development. Disruption of this gene has a recessive pleiotropic effect consisting on arrest of chloroplast development at an early stage, reduction of the expression of several photosynthetic genes, and absence of accumulation of photosynthetic pigments. Database searches show that the protein encoded by the CLA 1gene is highly conserved in evolution. We report the sequencing of a cDNA clone from rice that is homologous to the Arabidopsis CLA1. This is the first homolog of CLA1 characterized in monocot plants. The cDNA is 1785 basepairs in length. It contains an open reading frame (ORF) coding for 594 amino acids. The TPP binding sequence of the Arabidopsis CLA1 (residues 217 to 247) is well conserved in the rice homolog. The product of the CLA1 gene has significant similarity to transketolases and other enzymes that require thiamin pyrophosphate (TPP) as cofactor, suggesting an enzymatic function for this protein. It could may have a novel catalytic activity necessary for chloroplast development.