Transcriptional control of 2,4-dinitrotoluene degradation in Burkholderia sp. R34 bears a regulatory patch that eases pathway evolution
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Date
2021-05Author
Pérez Pantoja, Danilo
Nikel Mayer, Pablo Iván
Chavarría Vargas, Max
de Lorenzo, Víctor
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The dnt pathway of Burkholderia sp. R34 is in the
midst of an evolutionary journey from its ancestral,
natural substrate (naphthalene) towards a new xenobiotic
one [2,4-dinitrotoluene (DNT)]. The gene cluster
encoding the leading multicomponent ring
dioxygenase (DntA) has activity on the old and the
new substrate, but it is induced by neither. Instead, the
transcriptional factor encoded by the adjacent gene
(dntR) activates expression of the dnt cluster upon
addition of salicylate, one degradation intermediate of
the ancestral naphthalene route but not any longer a
substrate/product of the evolved DntA enzyme. Fluorescence
of cells bearing dntA-gfp fusions revealed
that induction of the dnt genes by salicylate was
enhanced upon exposure to bona fide DntA substrates,
i.e., naphthalene or DNT. Such amplification
was dependent on effective dioxygenation of these
pathway-specific head compounds, which thereby fostered
expression of the cognate catabolic operon. The
phenomenon seems to happen not through direct
binding to a cognate transcriptional factor but through
the interplay of a non-specific regulator with a
substrate-specific enzyme. This regulatory scenario
may ease transition of complete catabolic operons
(i.e. enzymes plus regulatory devices) from one substrate
to another without loss of fitness during the evolutionary
roadmap between two optimal specificities.
External link to the item
10.1111/1462-2920.15472Collections
- Química [360]