Four regions without a close known match.
Four of the 12 predicted regions in the public N4 genome lack a close reference: terpene regions 1.3 and 1.6, terpene-precursor region 1.8, and type III PKS region 1.7, whose best match shares only 16% of reference genes. These are the least characterized places to look first.
1. What this genome supports
Four of the 12 predicted regions lack a close known-cluster match. Terpene region 1.6 includes sqhC, annotated as sporulenol synthase, at 2,242,255–2,244,153 bp. Type III PKS region 1.7 includes bpsA, a type III polyketide synthase, and bpsB, an alkylpyrone methyltransferase, at 2,322,089–2,323,696 bp; its best reference match, a carbapenem cluster, shares only 16% of reference genes. Region 1.8 contains the isoprenoid-precursor genes dxs and ispA. Terpene region 1.3 includes farP, annotated as a farnesyl diphosphate phosphatase, but its annotations name no product.
2. What published research adds
Bosak et al. (2008) identified sporulenes, polycyclic terpenoids in B. subtilis spores, and showed that they increase spore resistance to a reactive oxygen species. Nakano et al. (2009) showed that BpsA synthesizes triketide pyrones and BpsB methylates them into alkylpyrone methyl ethers in B. subtilis. The signature genes of regions 1.6 and 1.7 therefore already have published explanations, and the 16% carbapenem match is weak context, not evidence of a carbapenem pathway. These studies do not establish what N4 itself produces.
3. How I would follow the evidence
Treat regions 1.6 and 1.7 as likely known chemistry until a measurement says otherwise, and start with region 1.3, the least explained of the four. Check each region’s boundaries and annotated genes against the sequence, then profile N4’s metabolites under relevant growth conditions and compare them with known sporulenes and alkylpyrones. That separates rediscovery from a genuinely new compound before you commit lab time. A useful follow-up is: “Which genes in region 1.3 lack a characterized homolog?”