The secondary structure of Nosema apis large subunit ribosomal RNA.

The microsporidia are a group of obligate intracellular eukaryotic parasites, that lack mitochondria. Their ribosomes show several prokaryote-like features. This paper presents the secondary structure of the large subunit ribosomal RNA (LSU rRNA) of the microsporidium Nosema apis. With its 2481 bases, it is the shortest known non-mitochondrial LSU rRNA. The seemingly prokaryote-like features of the molecule cannot be used as evidence for the ancient origin of the microsporidia. The reduction in size can be attributed to changes in the regions of the LSU rRNA that are known to show great variability in length and sequence within the eukaryotes. The lack of fragmentation commonly seen in other eukaryotes may also be a derived feature.