Identification of the gene structure and promoter region of H+-translocating inorganic pyrophosphatase in rice (Oryza sativa L. ).

In order to determine the gene structure and promoter region of vacuolar H+-translocating inorganic pyrophosphatase (V-PPase), we isolated the genomic clones using a rice BAC library and probes derived from rice V-PPase cDNA (OVP1). The entire OVP1 gene is approx. 5.4 kb in length, and seven introns interrupt the coding sequence of OVP1. The first intron is extremely large (1869 bp), while the other introns are between 82 and 170 bp. A transcription initiation site, identified by a primer extension analysis, indicated the first exon to be 366 bp. A 1.1 kb fragment containing the 5'-flanking region of the first exon with the GUS reporter gene showed specific promoter activity in rice cells. These data show that the OVP1 gene is composed of eight exons and seven introns, and regulatory elements are present within 1.1 kb upstream from the first exon.