Scanning electron microscopy images of dehydrated cells of <i>D</i>. <i>radiodurans</i> deposited on aluminum plates and used in experimental set up of Tanpopo mission.

<p>(<b>A</b>, <b>B</b>) Scanning electron microscopy images, showing upper surface and inner content of multilayers of dehydrated <i>D</i>. <i>radiodurans</i> cells deposited on aluminum plates. (<b>C</b>, <b>D</b>) Higher magnification images displaying upper surface of multilayers of dehydrated cells of <i>D</i>. <i>radiodurans</i>. (<b>E</b>, <b>F</b>) Magnified images of tetracocci and diplococci of <i>D</i>. <i>radiodurans</i> taken from the inner part of dehydrated multilayers. (<b>A</b>, <b>C</b>, <b>E</b>) control cells of <i>D</i>. <i>radiodurans</i>; (<b>B</b>, <b>D</b>, <b>F</b>) cells of <i>D</i>. <i>radiodurans</i> exposed to UVC-vacuum conditions.</p

Molecular response of <i>D</i>. <i>radiodurans</i> experienced under UVC and vacuum conditions.

<p>First two levels of molecular pathways are represented which are affected by UVC irradiation under vacuum conditions.</p

Bar plot of KEGG categories (x-axis) with corresponding enrichment factors (y-axis).

<p><b>Categories with a minimum enrichment factor of two for either UVC/vacuum (blue) treated or control (red) conditions are mapped.</b> An enrichment factor of zero means that not a single protein in this category was upregulated in the displayed condition.</p

Heatmap of metabolites, which were considered different between cells of <i>D</i>. <i>radiodurans</i> exposed to UVC/vacuum and non-exposed control cells.

<p>Eucledian distance was used for calculating the dendrogram. *Identification was based on database research and not on a reference substance.</p

First two levels of gene ontology annotations of all proteins of <i>D</i>. <i>radiodurans</i>, which were identified in at least three out of four replicates in at least one condition.

<p>First two levels of gene ontology annotations of all proteins of <i>D</i>. <i>radiodurans</i>, which were identified in at least three out of four replicates in at least one condition.</p

Boxplot of genes encoding important damage response proteins in <i>D</i>. <i>radiodurans</i> under the conditions of UVC/vacuum exposure.

<p>For every gene, the z-scored LFQ intensities are compared between the control and UVC/vacuum condition. The lower and the upper hinges correspond to the first and the third quartiles. The whiskers extend a maximum of 1.5 times the inter-quartile range. Outliers are indicated as dots. Proteins which are encoded by the mapped genes: Clp protease subunits (clpP and clpX), DNA damage response proteins (ddrB and ddrD), chaperone (dnaK), DNA gyrase subunit A (gyrA), radiation response metalloprotease (irrE), DNA polymerase (polA), DNA repair protein (pprA), recombinase (recA), single-stranded DNA-binding protein (ssb); catalase (katA), uncharacterized protein (DR_A0146), superoxide dismutase (sodA), phytoene dehydrogenase (DR_0861), Pyridoxal 5’-phosphate synthase (pdxS and pdxT), thioredoxin reductase (DR_1982), putative peroxidase (DR_A0145), peptide methionine sulfoxide reductase (msrA), tellurium resistance protein (DR_2220 and DR_2221).</p

Proteometabolomic response of <i>Deinococcus radiodurans</i> exposed to UVC and vacuum conditions: Initial studies prior to the Tanpopo space mission

<div><p>The multiple extremes resistant bacterium <i>Deinococcus radiodurans</i> is able to withstand harsh conditions of simulated outer space environment. The Tanpopo orbital mission performs a long-term space exposure of <i>D</i>. <i>radiodurans</i> aiming to investigate the possibility of interplanetary transfer of life. The revealing of molecular machinery responsible for survivability of <i>D</i>. <i>radiodurans</i> in the outer space environment can improve our understanding of underlying stress response mechanisms. In this paper, we have evaluated the molecular response of <i>D</i>. <i>radiodurans</i> after the exposure to space-related conditions of UVC irradiation and vacuum. Notably, scanning electron microscopy investigations showed that neither morphology nor cellular integrity of irradiated cells was affected, while integrated proteomic and metabolomic analysis revealed numerous molecular alterations in metabolic and stress response pathways. Several molecular key mechanisms of <i>D</i>. <i>radiodurans</i>, including the tricarboxylic acid cycle, the DNA damage response systems, ROS scavenging systems and transcriptional regulators responded in order to cope with the stressful situation caused by UVC irradiation under vacuum conditions. These results reveal the effectiveness of the integrative proteometabolomic approach as a tool in molecular analysis of microbial stress response caused by space-related factors.</p></div

PCA score-plot of the z-scored label free quantification intensities.

<p>A clear separation can be observed on the PC1 level, which explains 34.62% of the data’s variance, between the UVC/vacuum treated samples (red) and the control samples (green).</p