Halophilic archaea cultivated from surface sterilized middle-late eocene rock salt are polyploid

Peer reviewe

Insight into the assembly of viruses with vertical single β-barrel major capsid proteins

Archaeal viruses constitute the least explored niche within the virosphere. Structure-based approaches have revealed close relationships between viruses infecting organisms from different domains of life. Here, using biochemical and cryo-electron microscopy techniques, we solved the structure of euryarchaeal, halophilic, internal membrane-containing Haloarcula hispanica icosahedral virus 2 (HHIV-2). We show that the density of the two major capsid proteins (MCPs) recapitulates vertical single β-barrel proteins and that disulfide bridges stabilize the capsid. Below, ordered density is visible close to the membrane and at the five-fold vertices underneath the host-interacting vertex complex underpinning membrane-protein interactions. The HHIV-2 structure exemplifies the division of conserved architectural elements of a virion, such as the capsid, from those that evolve rapidly due to selective environmental pressure such as host-recognizing structures. We propose that in viruses with two vertical single β-barrel MCPs the vesicle is indispensable, and membrane-protein interactions serve as protein-railings for guiding the assembly

Crystal samples from 800 m visualized by light microscopy.

<p>(A) A salt crystal chiseled off from the surface sterilized isolation sample. (B) A magnification of a subsection of (A), showing liquid inclusions inside the crystal. (C) Cubic liquid inclusions. Bars represent 0.5 mm in A and C, and 0.1 mm in B.</p

Sampling location and the drill core sample.

<p>(A) The map of Yunying Depression, with the sampling site, Yingcheng (30° 55′ N, 113°34′ E), bolded and marked with a black dot. (B) Subsections of a drill core from the site. (C) The 600 m (D) and the 800 m samples, of which subsections were used for microbe isolation in this work. The bars in C and D represent 5 cm.</p

Archaeal strains isolated in this study.

<p>Archaeal strains isolated in this study.</p

Microbes isolated from rock salt drill core sample from the depth of 800 m.

<p>(A) The whole cell protein analysis of the isolates by SDS-PAGE. The numbers refer to strains YI80-1 to YI80-8. Molecular mass markers are shown on left. (B) Light microscopy pictures of the isolates in late stationary phase. The scale bar in YI80-1 represents 10 µm, and is applicable to all pictures. (C) Phenotypic characteristics of the isolates.</p

Oligonucleotides used in this study.

<p>Oligonucleotides used in this study.</p

Maximum likelihood phylogenetic tree of the 16S rRNA gene sequences.

<p>GenBank numbers are given in brackets. <i>Halolamina</i> species are marked with a pink background, and species of <i>Halobacterium</i> with light blue one. Strains isolated from the 800 m rock salt sample are bolded, and partial sequences marked with an asterisk (*). Bar represents inferred substitutions per nucleotide position. <i>Methanospirillum hungatei</i> is used as an outgroup.</p