Under anaerobic conditions, structurally diverse aromatic compounds are catabolized by bacteria to form @entity68620 ( @entity68620 ), the starting compound for a central reductive pathway for aromatic ring degradation. The structural genes required for the conversion of @entity16366 ( @entity48853 ) to @entity68620 by @entity16993 have been identified. Here we describe a regulatory gene, hbaR, that is part of the @entity48853 degradation gene cluster. An hbaR mutant that was constructed was unable to grow anaerobically on @entity48853 . However, the mutant retained the ability to grow aerobically on @entity48853 by an @entity26 -requiring pathway distinct from the anaerobic route of @entity48853 degradation. The effect of the HbaR protein on expression of hbaA encoding @entity48853 -CoA ligase, the first enzyme for @entity48853 degradation, was investigated by using hbaA::'lacZ transcriptional fusions. HbaR was required for a 20-fold induction of beta-galactosidase activity that was observed with a chromosomal hbaA::'lacZ fusion when cells grown anaerobically on succinate were switched to anaerobic growth on @entity4588 and @entity48853 . HbaR also activated expression from a plasmid-borne hbaA-'lacZ fusion when it was expressed in aerobically grown @entity796 cells, indicating that the activity of this regulator is not sensitive to @entity26 . The deduced @entity535 sequence of HbaR indicates that it is a member of the FNR-CRP superfamily of regulatory proteins. It is most closely related to transcriptional activators that are involved in regulating @entity1507 reduction. Previously, it has been shown that @entity16993 has an FNR homologue, called AadR, that is also required for @entity48853 degradation. Our evidence indicates that AadR activates expression of hbaR in response to anaerobiosis and that HbaR, in turn, activates expression of @entity48853 degradation in response to @entity48853 as an effector molecule.

HbaR, a @entity16366 sensor and FNR-CRP superfamily member, regulates anaerobic XXXX degradation by @entity16993 .

@entity48853 :: ('MESH:C459561', 'Chemical') :: ['4-HBA'] @entity796 :: ('287', 'Species') :: ['Pseudomonas aeruginosa'] @entity16993 :: ('1076', 'Species') :: ['R. palustris', 'Rhodopseudomonas palustris'] @entity4588 :: ('MESH:D019802', 'Chemical') :: ['succinate'] @entity535 :: ('CHEBI:33704', 'Chemical') :: ['amino acid'] @entity26 :: ('MESH:D010100', 'Chemical') :: ['oxygen'] @entity1507 :: ('CHEBI:48107', 'Chemical') :: ['nitrate'] @entity16366 :: ('MESH:C038193', 'Chemical') :: ['4-hydroxybenzoate'] @entity68620 :: ('MESH:C037817', 'Chemical') :: ['benzoyl-coenzyme A', 'benzoyl-CoA']
@entity16366 :: (MESH:C038193,Chemical) :: ['4-hydroxybenzoate']
