Ty and Ty-mediated gene expression observed in haploid cells of Saccharomyces cerevisiae depends on several determinants, some of which are required for the expression of haploid-specific genes. We report here the cloning and molecular analysis of TECJ. TEC1 encodes a 486-amino-acid protein that is a trans-acting factor required for full Tyl expression and Tyl-mediated gene activation. However, mutation or deletion of the TEC1 gene had little effect on total Ty2 transcript levels. Our analysis provides clear evidence that TEC1 is not involved in mating or sporulation processes. Unlike most of the proteins involved in Ty and adjacent gene expression, the product of TEC1 has no known cellular function. Although there was no mating-type effect on TEC1 expression, our results indicate that the TEC1 and the alao diploid controls on Tyl expression are probably not cumulative.

The fla gene of Borrelia burgdorferi GeHo was analyzed and expressed in Escherichia coli. The structural gene encodes a flagellar protein of 336 amino acids. Comparative sequence analysis of the amino acid sequence revealed a high degree of sequence conservation with flagellins from both phylogenetically related and unrelated bacteria. The antigenic properties of the B. burgdorferi Fla protein were studied by synthesizing overlapping octapeptides, which were screened by using a battery of different monoclonal and polyclonal antibodies from various species directed against native and denatured flagellar proteins. No single species-independent immunodominant epitope could be located. However, immunoreactive oligopeptides clustered within the variable middle region (N-180 to I-260). This region could constitute a candidate antigen for more specific and sensitive serodiagnosis of Lyme borreliosis.

In S. cerevisiae, the synthesis of ureaamidolyase is subject to at least two different forms of regulation: nitrogen catabolite repression and induction by allophanate. Two positive regulatory genes DURM and DURL are involved in the induction process. We have measured the levels of mRNA homologous to the DUR2,1 gene in conditions of ureaamidolyase induction and in regulatory mutants. The amounts of DUR2,1 enzyme and messengers are well coordinated; moreover, the half life of DUR2,1 messengers is identical in the presence or absence of inducer. These data suggest that the ureaamidolyase production is probably controlled at the level of transcription. From a pool of hybrid plasmids carrying Sau3A fragments representing the entire yeast genome, a 13 kb DNA fragment containing the regulatory gene DURM was cloned by complementation of a durM mutation which prevents the growth on allantoin as sole nitrogen source. Cells containing the cloned DNA recover the inducibility of ureaamidolyase by allophanate. Four RNA transcripts have homology to this 13 kb DNA fragment but the study of subcloned restriction endonuclease fragments allowed us to map the DURM regulatory gene within a 4 kilobase pair region. This fragment encodes a 1 kb transcript. The level of this RNA is the same in induced and non-induced cells.

Ty and Ty-mediated gene expression observed in haploid cells of Saccharomyces cerevisiae depends on several determinants, some of which are required for the expression of haploid-specific genes. We report here the cloning and molecular analysis of TEC1. TEC1 encodes a 486-amino-acid protein that is a trans-acting factor required for full Ty1 expression and Ty1-mediated gene activation. However, mutation or deletion of the TEC1 gene had little effect on total Ty2 transcript levels. Our analysis provides clear evidence that TEC1 is not involved in mating or sporulation processes. Unlike most of the proteins involved in Ty and adjacent gene expression, the product of TEC1 has no known cellular function. Although there was no mating-type effect on TEC1 expression, our results indicate that the TEC1 and the a/alpha diploid controls on Ty1 expression are probably not cumulative.