Mean DNA bend angle and distribution of DNA bend angles in the CAP-DNA complex in solution.
In order to define the mean DNA bend angle and distribution of DNA bend angles in the catabolite activator protein (CAP)-DNA complex in solution under standard transcription initiation conditions, we have performed nanosecond time-resolved fluorescence measurements quantifying energy transfer betwee...
| Main Authors: | , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
2001
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| Summary: | In order to define the mean DNA bend angle and distribution of DNA bend angles in the catabolite activator protein (CAP)-DNA complex in solution under standard transcription initiation conditions, we have performed nanosecond time-resolved fluorescence measurements quantifying energy transfer between a probe incorporated at a specific site in CAP, and a complementary probe incorporated at each of five specific sites in DNA. The results indicate that the mean DNA bend angle is 77(+/-3) degrees - consistent with the mean DNA bend angle observed in crystallographic structures (80(+/-12) degrees ). Lifetime-distribution analysis indicates that the distribution of DNA bend angles is relatively narrow, with <10 % of DNA bend angles exceeding 100 degrees. Millisecond time-resolved luminescence measurements using lanthanide-chelate probes provide independent evidence that the upper limit of the distribution of DNA bend angles is approximately 100 degrees. The methods used here will permit mutational analysis of CAP-induced DNA bending and the role of CAP-induced DNA bending in transcriptional activation. |
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