Comparison of MCR patterns for carbon fixation in “<i>Ca</i>. C. subterraneum” and three thaumarchaeotic species.

<p><b>1.</b> MCR patterns of six major carbon fixation pathways. 3–HP bicycle, 3–hydroxypropionate bicycle; HP–HB cycle, hydroxypropionate–hydroxybutyrate cycle; dicarboxylate HB cycle, dicarboxylate hydroxybutyrate cycle; <b>2,</b> Mapping patterns of genes to two carbon fixation modules. Numbers in parentheses show the order of reaction steps in each module. In each “K number” set of components of the module, the vertically connected and horizontally located K numbers indicate complexes and alternatives, respectively [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132994#pone.0132994.ref019" target="_blank">19</a>]. <b>(A)</b> Reductive TCA cycle (M00173). *Specific enzymes for this pathway; §found only in <i>Cenarchaeum symbiosum</i>. <b>(B)</b> HP–HB cycle (M00375). Numbers in red show the reaction steps for which the corresponding genes were not identified in the genomes of the three thaumarchaeotic species, although their enzymatic activities have been detected experimentally [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132994#pone.0132994.ref044" target="_blank">44</a>]. *The gene responsible for step 3 has been experimentally identified in the <i>N</i>. <i>maritimus</i> genome very recently, whereas the K number has not yet been assigned to the gene (Nmar_1110) by KEGG [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132994#pone.0132994.ref048" target="_blank">48</a>]. **Because the K numbers were incorrectly assigned to the genes of thaumarchaeotic species, the genes responsible for steps 10 and 11 have not yet been identified in their genomes.