<p>These proteins are members of the wider radical SAM superfamily of enzymes that enzymes utilise an iron-sulphur redox cluster and S-adenosylmethionine to carry out diverse radical mediated reactions [<cite idref="PUB00010539"/>]. The <taxon tax_id="243159">Acidithiobacillus ferrooxidans ATCC 23270</taxon> protein (AFE_0975) is encoded in the same locus as the genes for squalene-hopene cyclase (SHC, <db_xref db="INTERPRO" dbkey="IPR006400"/>) and other proteins associated with the biosynthesis of hopanoid natural products. Similarly, in <taxon tax_id="264198">Ralstonia eutropha</taxon> (strain JMP134) (Alcaligenes eutrophus) (Reut_B4901) this protein is encoded adjacent to the genes for HpnAB, IspH and HpnH (<db_xref db="INTERPRO" dbkey="IPR017833"/>), although SHC itself is elsewhere in the genome. Notably, this protein (here named HpnJ) and three others form a conserved set (HpnIJKL) which occur in a subset of all genomes containing the SHC enzyme. This relationship was discerned using the method of partial phylogenetic profiling [<cite idref="PUB00034422"/>]. This group includes <taxon tax_id="542">Zymomonas mobilis</taxon> the organism where the initial hopanoid biosynthesis locus was described consisting of the genes HpnA-E and SHC (HpnF) [<cite idref="PUB00042985"/>]. Continuing past SHC are genes encoding a phosphorylase enzyme (ZMO0873, i.e. HpnG, <db_xref db="INTERPRO" dbkey="IPR017831"/>) and another radical SAM enzyme (ZMO0874), HpnH. Although discontinuous in Z. mobilis, we continue the gene symbol sequence with HpnIJKL. One of the well-described hopanoid intermediates is bacteriohopanetetrol. In the conversion from hopene several reactions must occur in the side chain for which a radical mechanism might be reasonable. These include the four (presumably anaerobic) hydroxylations and a methyl shift.</p> Hopanoid biosynthesis associated radical SAM protein HpnJ