The Mucorales contain an atypical Trl1 ortholog with only the “sealing” domain. (A) Schematic of the tRNA splicing pathway in yeast and human. (B) Domain architecture of Saccharomyces cerevisiae Trl1 and orthologs from Mucorales (Rhizopus arrhizus, Mucor circinelloides, Phycomyces blakesleeanus, Lichtheimia corymbifera), the closely related Umbelopsidales Umbelopsis vinacea, and the more distantly related Rhizophagus irregularis and Entomortierella lignicola. (LIG) ligase domain, (KIN) kinase domain, and (CPD) cyclic phosphodiesterase domain. The species tree is from Zhao et al. (2022). (C) The tRNA LIG of M. circinelloides and R. arrhizus express as sealing-only single domain Trl1s, whereas R. irregularis Trl1 contains three domains. Shown is RNA-seq read coverage of the TRL1 orthologs of M. circinelloides, R. arrhizus (both Mucorales), and the related R. irregularis tRNA LIG. Colors reflect domains as in A. (D) The Mucorales contain a minimal set of intron-containing tRNAs. The number of intronless isodecoders (white), intron-containing isodecoders (gray), and intron-containing Tyr GUA (decoding UAC and UAU codons) and Ile UAU (decoding AUA codons) (dark gray) isodecoders in the genomes of major pathogenic fungi is shown.
