The gene encoding T protein of the glycine decarboxylase complex involved in the mitochondrial step of the photorespiratory pathway in plants exhibits features of light-induced genes

摘要

A genomic clone encoding the 41 kDa monomer T-protein was isolated from pea (Pisum sativum cv. Alaska) and characterized. This gene, called gdcT, spans approximately 3 kb and is composed of four exons interrupted by three introns (of 321, 691 and 114 bp). The splice sites for donor and acceptor are in agreement with the canonical GT/AG rule. Primer extension strongly suggests the presence of two major transcription start sites. The first transcription start site, around 43 bases downstream of a putative TATA box, was assigned the +1 position. The second (+31) is not correlated with a putative TATA box, but revealed a pyrimidine-rich region which similar to the initiator element. Sequence analysis of the 5'-upstream region of the gene revealed three consensus regions found in the nuclear genes encoding the chloroplastic proteins of ribulose-bisphosphate carboxylase (rbcS) and the chlorophyll a/b-binding protein (cab), such as an AT-rich sequence localized at -539 to -530, a box II core sequence GGTTAA (-123 to -118) and, between -364 and -354, a tandem GATA motif. These elements are known to be involved in the regulation of light-responsiveness and cell-type specificity expression of plant genes. Gel shift assays indicated that the box II core sequence could bind protein nuclear factors similar to the trans-acting factor which interacts with the corresponding promoter region of rbcS gene. Nucleotide sequence data have been submitted to the EMBL/GenBank/DDBJ databases under the accession number AJ222771.