Complex evolutionary history of translation Elongation Factor 2 and diphthamide biosynthesis in Archaea and parabasalids
Diphthamide is a modified histidine residue which is uniquely present in archaeal and eukaryotic elongation factor 2 (EF-2), an essential GTPase responsible for catalyzing the coordinated translocation of tRNA and mRNA through the ribosome. In part due to the role of diphthamide in maintaining translational fidelity, it was previously assumed that diphthamide biosynthesis genes (dph) are conserved across all eukaryotes and archaea. Here, comparative analysis of new and existing genomes reveals that some archaea (i.e., members of the Asgard superphylum, Geoarchaea, and Korarchaeota) and eukaryotes (i.e., parabasalids) lack dph. In addition, while EF-2 was thought to exist as a single copy in archaea, many of these dph-lacking archaeal genomes encode a second EF-2 paralog missing key-residues required for diphthamide modification and for normal translocase function, perhaps suggesting functional divergence linked to loss of diphthamide biosynthesis. Interestingly, some Heimdallarchaeota previously suggested to be most closely related to the eukaryotic ancestor maintain dph genes and a single gene encoding canonical EF-2. Our findings reveal that the ability to produce diphthamide, once thought to be a universal feature in archaea and eukaryotes, has been lost multiple times during evolution, and suggest that anticipated compensatory mechanisms evolved independently.
Here is some of the press that covered the impacts of the storm on my lab, institute, lab members, and family.
Congrats Nina and Kiley!
This paper details the genetic diversity of these sediments and describes genomes belonging to a uncultured archaeal group (GoM-Arc1) that contain novel pathways for hydrocarbon cycling, related to ANME (anaerobic methane oxidizers).
In addition to Theionarchaea, this new paper that appears in ISME Journal also details a variety of archaeal genomes there were obtained from the White Oak River Estuary in North Carolina. This digram summarizes the ecological roles we have inferred from these genomes. This is important because NONE of these lineages have been grown in a laboratory, so having their genomes has significantly advanced our understanding of what they do in nature.
This week our new paper describing the discovery of 4 archaea phyla that are related to eukaryotes was published in Nature. These phyla are belong to the same branch of life and have been named after different Norse gods, Thor, Odin, Heimdall, and Loki. This is a collaboration with Thijs Ettema’s lab in Sweden. Last year we published the discovery of Thorarchaeota in ISME.
This paper adds 2 additional phyla, Odinarchaeota and Heimdallarchaeota. The focus of this paper is further resolve the phylogenetic position of eukaryotes in this new superphylum. It also examines the presence of several new ESPs or eukaryotic signature proteins. These proteins were mostly thought to exist in eukaryotes, but these genomes contain a variety of them!
Press releases to accompany this study: