Organelles that illuminate the origins of Trichomonas hydrogenosomes and Giardia mitosomes

Barthelonids represent a deep-branching Metamonad clade with mitochondrion-related organelles generating no ATP

“…(iv) The redundancy in the ATP-generating system allowed the secondary loss of substrate-level phosphorylation in the MRO prior to the separation of the D. brevis plus diplomonad clade. We here extend the scenario proposed by Leger et al (2017) by incorporating the data from Barthelona sp. strain PAP020 (See Fig.…”

“…Leger et al (2017) proposed that the ancestral fornicate species possessed an MRO with a metabolic capacity similar to that of the hydrogenosomes in parabasalids like Trichomonas vaginalis . Thus, we surveyed the transcriptomic data from strain PAP020 for transcripts encoding hydrogenosomal/MRO proteins that are homologous to Trichomonas proteins localized in the hydrogenosome.…”

“…We subjected the two ACS sequences to a phylogenetic analysis along with the homologues sampled from diverse bacteria, archaea and eukaryotes (Fig S3). The PAP020 ACS2 sequence formed a clade with fornicate “ACS2” sequences, which Leger et al (2017) proposed to be cytosolic enzymes. Thus, we suggest that ACS2 is most likely a cytosolic enzyme in strain PAP020 as well.…”

“…Leger et al (2017) proposed a complex evolution of ATP-generating mechanisms in the Fornicata clade, as follows: (i) The ancestral fornicate species possessed both substrate-level phosphorylation in the MRO as well as ACS2 in the cytosol. (ii) Substrate-level phosphorylation has been inherited vertically to the extant fornicate species, except D. brevis and diplomonads (see below).…”

Microbial Eukaryotes that Lack Sterols

“…tBlastX (Altschul et al 1997) was used to screen genes encoding oxidosqualene cyclase (OSC), squalene-tetrahymanol cyclase (STC), and squalene-hopene cyclase (SHC) in the transcriptome datasets of the anaerobic protists, B. motovehiculus (SRP081237 in Gawryluk et al 2016), K. bialata (SRP077666 in Leger et al 2017), C. marsupialis (DRX027417 in Noguchi et al 2015), and P. biforma (SRX246005 in Stairs et al 2014), by using the OSC sequence of Homo sapiens (GenBank accession number AAH35638), the STC sequence of Tetrahymena thermophila (GenBank accession number XM_001026696), and the SHC sequence of Thermosynechococcus elongatus (GenBank accession number WP_ 011058142) as queries, respectively. The deduced amino acid sequences of two copies of the STC gene from B. motovehiculus identified in this study were aligned with the triterpene cyclase protein family from various prokaryotic and eukaryotic species using MAFFT v7.164b (Katoh and Standley 2013).…”