Two proteins with different functions are derived from the KlHEM13 gene

Area of Science:

• Molecular Biology
• Yeast Genetics
• Gene Regulation

Background:

• The KlHEM13 gene in Kluyveromyces lactis encodes two N-terminal variants: l-KlCpo and s-KlCpo.
• Gene expression is regulated by heme availability, influencing transcriptional start site (TSS) selection.

Purpose of the Study:

• To investigate the functional roles and regulatory mechanisms of l-KlCpo and s-KlCpo.
• To elucidate the heme-dependent regulation of the KlHEM13 gene.

Main Methods:

• Primer extension assays to detect transcriptional start sites.
• Functional complementation assays using a Δhem13 deletion mutant.
• Immune detection in subcellular fractions.
• Directed mutagenesis and chromatin immunoprecipitation (ChIP) assays.

Main Results:

• Two distinct TSS pools were identified, with selection dependent on heme levels.
• Only the s-KlCpo protein could rescue the heme deficiency phenotype in Δhem13 mutants.
• Evidence suggests l-KlCpo plays a regulatory role in KlHEM13 transcription.

Conclusions:

• The KlHEM13 gene produces two functional proteins with distinct roles.
• Heme-dependent regulation controls KlHEM13 gene expression through differential TSS selection.
• l-KlCpo acts as a transcriptional regulator of the KlHEM13 gene.