TANDEM ORGANIZATION AND HIGHLY DISPARATE EXPRESSION OF THE 2 LACCASE GENES LCC1 AND LCC2 IN THE CULTIVATED MUSHROOM AGARICUS-BISPORUS

Two non-allelic laccase genes (lcc1 and lcc2) in Agaricus bisporus hav e been mapped to the same cosmid clone and are close together, in tand em. The intergenic region consists of 1562 bp between the stop codon o f lcc1 and the start codon of lcc2. Differences between the 5' non-cod ing regions of the two genes suggest the potential for their different ial regulation. By employing competitive RT-PCR and specific primer pa irs that discriminate between lcc1 and lcc2, it has been shown that th e level of lcc2 mRNA is approximately 300 times higher than that of lc c1 mRNA in malt extract liquid cultures; in compost cultures lcc2 mRNA is almost 7000 times more abundant than lcc1 mRNA.