Tubulin Polymerization Promoting Proteins (TPPPs) of Aphelidiomycota: Correlation between the Incidence of p25alpha Domain and the Eukaryotic Flagellum

Abstract

The seven most early diverging lineages of the 18 phyla of fungi are the non-terrestrial fungi, which reproduce through motile flagellated zoospores. There are genes/proteins that are present only in organisms with flagellum or cilium. It was suggested that TPPP-like proteins (proteins containing at least one complete or partial p25alpha domain) are among them, and a correlation between the incidence of the p25alpha domain and the eukaryotic flagellum was hypothesized. Of the seven phyla of flagellated fungi, six have been known to contain TPPP-like proteins. Aphelidiomycota, one of the early-branching phyla, has some species (e.g., Paraphelidium tribonematis) that retain the flagellum, whereas the Amoeboaphelidium genus has lost the flagellum. The first two Aphelidiomycota genomes (Amoeboaphelidium protococcorum and Amoeboaphelidium occidentale) were sequenced and published last year. A BLASTP search revealed that A. occidentale does not have a TPPP, but A. protococcorum, which possesses pseudocilium, does have a TPPP. This TPPP is the ‘long-type’ which occurs mostly in animals as well as other Opisthokonta. P. tribonematis has a ‘fungal-type’ TPPP, which is found only in some flagellated fungi. These data on Aphelidiomycota TPPP proteins strengthen the correlation between the incidence of p25alpha domain-containing proteins and that of the eukaryotic flagellum/cilium.

The Unicellular, Parasitic Fungi, Sanchytriomycota, Possess a DNA Sequence Possibly Encoding a Long Tubulin Polymerization Promoting Protein (TPPP) but Not a Fungal-Type One

“…An interesting point is that not all Chytridiomycota TPPP/p25alpha domain can be found in the same clade. The unusual (different from the species phylogeny) position of Caulochytrium TPPP was found earlier, too [ 22 , 23 ]; the reason for it is not known. Another case is the species included in the dotted box in Figure 6 labeled with ‘2’ following the species name.…”

“…The very same alga has other fungal parasites, Aphelidium tribonematis [ 32 ] and Paraphelidium tribonematis [ 33 ], which belong to the phylum Aphelidiomycota and did not lose their flagellum [ 34 ]. Based on the genomic/proteomic data published in references [ 11 ] and [ 35 ], it has been shown that both of them possess a fungal-type TPPP ( Figure S1 and [ 22 ]). However, species of another genus of the phylum, Amoeboaphelidium , are characterized by the presence of a non-motile pseudocilium [ 10 , 36 ], similarly to sanchytrids.…”

“…There is only long TPPP in animals thus long TPPP is also named ‘animal-type’ TPPP [ 12 , 22 ]. A special, ‘fungal-type’ TPPP, which contains both a full and a partial p25alpha domain ( Figure 1 ), is present only in certain fungi [ 12 , 22 , 23 ]. In general, there is high homology between the C-terminus of the full-length domain and the partial domain [ 23 ].…”

“…It was shown earlier that members of all phyla of flagellated fungi contain TPPP-like proteins: Rozellomycota, Chytridiomycota, Neocallimastigomycota, Monoblepharomycota, and Blastocladiomycota [ 12 ]; Olpidiomycota [ 23 ]; Aphelidiomycota [ 22 ]. On the other hand, terrestrial fungi do not contain these kinds of proteins [ 12 ].…”

Presence of p25alpha-Domain in Seed Plants (Spermatophyta): Microbial/Animal Contaminations and/or Orthologs

“…In this study, the sequences of seed plants (Spermatophyta) deposited in the NCBI databases were systematically examined for the presence of the p25alpha domain. This domain is found in TPPP-like proteins, which are absent in land plants [ 10 , 23 ]. The reason for this is that the p25alpha domain is connected to the presence of flagellum/cilium, which was lost from most land plants during evolution [ 11 ].…”