Acenaphthylene and acenaphthalene, polyaromatic hydrocarbons (PAHs), are constituents of coal tar and tobacco smoke. Their degradation serves as a model for bridged PAH metabolism.
Rhizobium sp. CU-A1 and Stenotrophomonas sp. RMSK can use acenaphthylene as their sole source of carbon and energy. The pathway involves dioxygenation at the bridge double bond to form 1,2-dihydroxyacenaphthalene, a tautomer of 1-hydroxy-2-ketoacenaphthene. Naphthalene 1,2-dioxygenase, the enzyme which can initiate this route of bacterial acenaphthylene metabolism (Selifonov et al., 1996), has many other catalytic abilities, which are documented in a table of Reactions of Naphthalene 1,2-Dioxygenase.
1-Hydroxy-2-ketoacenaphthene is oxidized to acenaphthenequinone, which is oxidatively cleaved to form naphthalene-1,8-dicarboxylate. This is decarboxylated to 1-naphthoic acid, which is further metabolized to salicylate, which can be transformed to gentisate or catechol (Poonthrigpun et al., 2006 and Nayak et al., 2009). A Beijerinckia sp. can metabolize acenaphthylene to acenaphthenequinone by a similar pathway, but no further (Schocken & Gibson, 1984).
Acenaphthalene is also degraded through acenaphthenequinone, though the inital metabolites are different. Beijerinchia sp., Pseudomonas sp. BR, BC and A2279, and Sphingomonas sp. A4 can transform acenaphthalene to 1-acenaphthalenol. This compound is either hydroxylated to form 1,2-dihydro-1,2-acenaphthylenediol, or the hydroxyl group is oxidized to form 1-ketoacenaphthene. Both of these compounds are oxidized to 1-hydroxy-2-ketoacenaphthene and from there to acenaphthenequinone (Schocken & Gibson, 1984, Selifonov et al., 1998, and Kouzuma et al., 2006).
The following is a text-format acenaphthylene map. An organism which can initiate the pathway is given, but other organisms may also carry out later steps. Follow the links for more information on compounds or reactions. This map is also available in graphic (10k) format.
Acenaphthylene Acenaphthalene Rhizobium sp. CU-A1 Beijerinckia sp. Stenotrophomonas sp. RMSK Pseudomonas sp. BR, BC, and A2279 Beijerinckia sp. Sphingomonas sp. A4 | | | naphthalene | acenaphthalene | 1,2-dioxygenase | monooxygenase | 1-acenaphthalenol | v 2-monooxygenase v [1,2-Dihydro-1,2-acenaphthylenediol] <------------------ 1-Acenaphthalenol | | | | | 1,2-dihydro-1,2-acenaphthylenediol | 1-acenaphthalenol | dehydrogenase | dehydrogenase | 1-ketoacenaphthalene | v 2-monooxygenase v [1-Hydroxy-2-ketoacenaphthene] <------------------- 1-Ketoacenaphthalene | | | 1-hydroxy-2-ketoacenaphthene | dehydrogenase | v Acenaphthenequinone not Beijerinckia | | A (spontaneous) | | v Naphthalene-1,8-dicarboxylate | | | naphthalene-1,8-dicarboxylate | decarboxylase | v 1-Naphthoic Acid | | | v to the 1-Naphthoic Acid Pathway
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