FIG 1 .

Aerobic 9,10-seco degradation pathways for cholesterol, cholate, and testosterone. The steroid nucleus is degraded by oxygen-dependent opening and subsequent hydrolytic cleavage of rings A and B, leading to the formation and further degradation of (3′-propanoate)-7aβ-methylhexahydro-1,5-indanediones (HIP) and 2-hydroxyhexa-2,4-dienonic acid (HPDOA). Names of characterized steroid degradation protein families with available hidden Markov models are highlighted in red. Dashed arrows indicate multiple enzymatic reactions.