Structure, evolution and anaerobic regulation of a nuclear gene encoding cytosolic glyceraldehyde-3-phosphate...

A nuclear gene encoding cytosolic glyceraldehyde-3-phosphate dehydrogenase from maize (subunit GAPC1, gene Gpc1) and 2.2 x 10(3) base-pairs of its 5' flanking region have been cloned and sequenced. The structure of the maize Gpc1 gene (10 introns) is different from that of the maize gene encoding subunit GAPA of chloroplast glyceraldehyde-3-phosphate dehydrogenase (1 intron) and relatively similar to that of the chicken gene (11 introns). Introns in the Gpc1 gene show a positional polarity; the more 3' their position, the more they are displaced relative to introns in the chicken gene. The Gpc1 gene and other nuclear genes from maize are associated with CpG islands, the relative size of which determines the degree of codon bias in the gene. The promoter of the maize Gpc1 gene contains an anaerobic regulatory element and a pyrimidine box upstream from the TATA box and within intron 1. Southern blotting analyses and Northern hybridizations suggest that there are three functional Gpc genes in maize whose transcript levels are controlled differentially by anaerobiosis. In spite of its "typical" anaerobic promoter, the Gpc1 gene does not seem to be an anaerobic gene in vivo.