Summary:
EbgR (for "evolved β-galactosidase repressor") negatively regulates
genes involved in the evolved β-galactosidase system, which
constitutes an alternative for lactose utilization in cells with mutations
on the lacZ gene [2, 3].
The wild-type Ebg enzyme, encoded by the ebg operon, is not
efficient enough to permit growth on lactose. Mutations in ebgR and
ebgA, however, enhance its catalytic activity and enable rapid
growth on lactose as a sole carbon source [2, 3].
EbgR belongs to the GalR-LacI family of transcriptional regulators. There
is strong evidence that the ebg and lac operons share a
common origin in evolution [2]. EbgR diverged from other
repressors shortly after the divergence of the Gram positive from the Gram
negative eubacteria, approximately 2.2 billion years ago
[4]
Reviews: [3, 4]
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