English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

OccR is a LysR-type transcriptional regulator of Agrobacterium tumefaciens that positively regulates the octopine catabolism operon of the Ti plasmid. Positive control of the occ genes occurs in response to octopine, a nutrient released from crown gall tumors. OccR also functions as an autorepressor in the presence or absence of octopine. OccR binds to a site between occQ and occR in the presence or absence of octopine, although octopine triggers a conformational change that shortens the DNA footprint and relaxes a DNA bend. In order to determine the roles of this conformational change in transcriptional activation, we isolated 11 OccR mutants that were defective in activation of the occQ promoter but were still capable of autorepression. The mutations in these mutants spanned most of the length of the protein. Two additional positive-control mutants were isolated using site-directed mutagenesis. Twelve mutant proteins displayed a high-angle DNA bend in the presence or absence of octopine. One mutant, the L26A mutant, showed ligand-responsive DNA binding similar to that of wild-type OccR and therefore must be impaired in a subsequent step in activation.

Most Mutant OccR Proteins That Are Defective in Positive Control Hold Operator DNA in a Locked High-Angle Bend