Our focus lies on the fascinating world of microsporidia, eukaryotic obligate intracellular parasites that share a close evolutionary relationship with fungi. These organisms showcase a remarkable example of genome compaction as an evolutionary adaptation to their parasitic lifestyle. Microsporidia have notably reduced genomes, having lost several key biological components over time, a consequence of their co-evolution with host species.

Our research investigates the intriguing hypothesis that microsporidia may selectively eliminate complex multi-gene transcription machinery during their evolutionary reduction, balancing the necessity to maintain essential genes for basic gene expression with the benefits of a streamlined genome. Despite conserving core transcription machinery, microsporidia appear to lack genes that regulate finer aspects of transcriptional control, potentially leading to less precise or controllable gene expression. Furthermore, similar to their specialized structures like the polar tube, microsporidia might employ specialized factors to regulate RNA synthesis uniquely. This exploration of microsporidian genome strategies enhances our understanding of intracellular parasitism and evolutionary biology.