As research into the biosynthesis of natural products has matured, the biosynthetic pathways of common skeletons have been identified one after another, and attention is now being focused on research into the biosynthetic machineries of compounds with rare skeletons. Such research has the potential for leading to the discovery of new biosynthetic enzymes and artificial biosynthesis of unnatural compounds. In this study, I introduce the biosynthetic research on altemicidin, SB-203207, and SB-203208, which are rare natural products containing sulfonamide and azaindane skeletons. Further, self-resistance gene mining, the biosynthetic machineries of aminoacyl transferases, the synthesis of sulfonamides and azaindanes, and the structural basis and reaction mechanism of the biosynthetic enzyme SzbP, which uses beta-nicotinamide adenine dinucleotide (β-NAD) and S-adenosylmethionine (SAM) as substrates to create the first intermediate in the biosynthesis, are discussed in detail.