Growth phase-dependent expression of Kluyveromyces lactis genes and involvement of 3′-UTR elements

The analysis of Kluyveromyces lactis gene expression by heterologous microarray hybridization and the study of individual genes from K. lactis relative to the growth phase are presented. A total of 248 open reading frames (ORFs) showed preferential expression at early or late logarithmic phases. Some individual genes were also analyzed by Northern blot in a comparative study between K. lactis and Saccharomyces cerevisiae for a more complete view of this regulatory mechanism in yeast. Taking into account the important role of 3′-untranslated regions (3′-UTR) elements in gene expression, the data obtained were used to analyze the 3′-UTR of these genes, searching for regulatory elements. As a result, two potential 3′-UTR cis-elements, MYC and GYC, involved in K. lactis growth phase-dependent regulation of mRNA levels were found in a specific set of genes of early and late logarithmic phases, respectively. The MYC consensus was proved to be functional on KlCYC1 as an element regulating early logarithmic mRNA abundance of its short transcript.