OVERLAPPING CODING REGIONS AND TRANSCRIPTIONAL UNITS OF 2 ESSENTIAL CHROMOSOMAL GENES (CCT8, TRP1) IN THE FUNGAL PATHOGEN CANDIDA-ALBICANS

Sequencing of the 3'-untranslated region of the CCT8 gene of the funga l pathogen Candida albicans revealed that the CCT8 coding region overl aps 13 bp with the coding region of the convergently orientated TRP1 g ene. The same overlap was found in three strains with different geneti c backgrounds. 3'-RACE was used to determine that the CCT8 and TRP1 tr anscripts extended significantly into the coding region of the adjacen t gene, which also contained sequences encoding the poly(A) addition s ite. A strain retaining one wild-type CCT8/TRP1 locus on one chromosom e and a deletion on the other homologous chromosome contained both CCT 8 and TRP1 transcripts; this result indicates that both transcripts ar e synthesized from the same gene locus. The CCT8/TRP1 gene pair of C,a lbicans constitutes an extreme natural case of transcriptional overlap in a eukaryote, The results confirm that convergent overlapping trans cription units are compatible with expression of the overlapping genes .