FIG 1.
Characterization of the identified Dasypus novemcinctus candidate env genes. (A) Schematic representation of a retroviral Env protein delineating the surface (SU) and transmembrane (TM) subunits. The furin cleavage site (consensus, R-X-R/K-R) between the two subunits, the C-X-X-C motif involved in the SU-TM interaction, the hydrophobic signal peptide (purple), the fusion peptide (green), the transmembrane domain (red), and the putative immunosuppressive domain (ISD) (blue) along with the conserved C-X5,6,7-C motif are indicated. (B) Retroviral envelope protein-based phylogenetic tree with the newly identified Dasy-Env protein candidates and families. Shown is a maximum likelihood tree using TM subunit amino acid sequences from a series of endogenous and infectious retroviruses and the syncytins. The horizontal branch length is proportional to the percentage of amino acid substitutions from the node (bar on the left), and the percent bootstrap values (>50%) obtained from 1,000 replicates are indicated at the nodes. Green, Dasypus novemcinctus candidate env genes; red, functional dasy-env1.1; blue, syncytin genes (“syn”) so far identified; black, selected series of infectious or endogenous retroviral env genes. RevA, avian reticuloendotheliosis virus; MPMV, Mason-Pfizer monkey virus; Env-Cav1, “syncytin-like” Cavia porcellus Env1 protein; GaLV, gibbon ape leukemia virus; PERV, porcine endogenous retrovirus; BaEV, baboon endogenous virus; HIV1, human immunodeficiency virus type 1; HERV, human endogenous retrovirus; MoMLV, Moloney murine leukemia virus; HTLV-2, human T-lymphotropic virus type 2; BLV, bovine leukemia virus; JSRV, Jaagsiekte retrovirus; MMTV, murine mammary tumor virus; FeLV, feline leukemia virus; RD114, feline endogenous type C retrovirus. (C) Characterization of the candidate Dasypus Env proteins. (Left) Hydrophobicity profile for representative candidates within each family is shown with the canonical structural features highlighted in panel A positioned, when present (same color code). Genomic coordinates for the Env protein-encoding sequences are given in Table S1 in the supplemental material, together with the identity of the representative Env candidates. (Right) Number of full-length env gene ORFs within each family of elements.