ELECTROPHORETIC KARYOTYPE OF THE AMYLOLYTIC YEAST LIPOMYCES-STARKEYI AND CLONING, SEQUENCING AND CHROMOSOMAL LOCALIZATION OF ITS TRP1 GENE

The genome of the amylolytic yeast strain Lipomyces starkeyi NCYC 1436 was analysed using contour-clamped homogeneous electric field gel ele ctrophoresis (CHEF). The banding pattern under a variety of running co nditions indicating the presence of 11 different chromosome-sized DNA molecules. The sizes of these chromosome bands were determined by comp arison with chromosomes from standard strains of Schizosaccharomyces p ombe and Saccharomyces cerevisiae. The chromosomal bands were estimate d to be within the range 0.7-2.8 Mb, with the genome (excluding mitoch ondrial DNA) estimated at 15 Mb. The molecular cloning of the TRP1 gen e, isolated from a genomic library of this strain, is also reported: t he gene was present on a 6.5-kb Sau3A DNA fragment, and complemented t he trpC gene of E. coli. The DNA sequence was determined (EMBL accessi on No. Z68292) and compared to other tryptophan biosynthetic genes enc oding N-(5'-phosphoribosyl) anthranilate isomerase (PRAI) activity. Th e gene was also used as a probe in hybridization studies, and by this means, its chromosomal location was identified.