A melanin polyketide synthase (PKS) gene from Nodulisporium sp that shows homology to the pks1 gene of Colletotrichum lagenarium

The melanin polyketide synthase (pks) gene of Nodulisporium sp. MF5954 (ATC C74245) was cloned by exploiting its homology to the Colletotrichum lagenar ium pks1 gene. Sequence analysis demonstrated that this gene is 70% identic al to the C. lagenarium pks1 gene. A gene disruption construct, designed to replace both the ketoacyl synthase and acyl transferase domains with a hyg romycin resistance (Hy(r)) gene, was synthesized, and used to disrupt the N odulisporium melanin pks1 gene via homologous recombination, resulting in a mel(-) phenotype. Sequence analyses of the gene and of cDNA segments gener ated by RT-PCR indicate that there are three introns in the 5' half of the gene. The proposed 2159-amino acid product is 72% identical and 78% similar to the 2187-amino acid sequence deduced from the C. lagenarium pks1 gene. This similarity is notable, considering that C. lagenarium is a member of t he order Phyllachoales or Sordariales, whereas Nodulisporium is generally b elieved to be member of the order Xylariales. However, despite the strong r esemblance between the amino acid sequences in the acyl transferase domains of the two proteins, only one in five codons are conserved in the DNA sequ ences that encode this motif. The Nodulisporium sp. pks1 gene sequence and the amino acid sequence deduced from its coding region have been deposited in Genbank under Accession No. AF151533.