Difference between revisions of "Part:BBa K079043"

Latest revision as of 17:39, 29 October 2008

Lambda OR3 - operator library member

This parts have been extracted from the Lambda Operator Library.

Right Regulatory Elements position in natural cI genetic switch

Lambda Genetic switch is a complex and deeply characterized system. A Review on the natural phage behavior can be useful to delve into this operator set characteristics

Test System used to assay Biological Activity

ΔG of cI Binding to it's different operator sites and resulting Biological repression strength expressed as reduction in LacZ Activity

K079041: Lambda OR1 is the most affine wild type operator sequence in the Lambda system. In the natural switch overlaps with Cro Promoter PR.

K079042: Lambda OR2 is located upstream of OR1 partially overlapping the PR promoter. cI binding affinity for the operator sequence is significantly lower than OR1 (Higher Free Energy)

K079043: Lambda OR3 recruits cI with interaction energy comparable to OR2. The different biological role in the switch systems is related to positional effects being OR3 farther from PR sequence and overlapping cI promoter P.

The resuming table clearly shows as, to determine the actual repression strength both binding affinity and positional effects are key elements. For Example OR3 has the strongest repression despite the lower binding affinity and a very different repression efficiency compared to the similarly binding OR2.

Relative Cro Binding Strength defined as ORn/OR1

OR2 and OR3 have been selected despite the similar cI binding properties because OR sites can be specifically recognized as well by Cro repressor protein. In Cro interaction the increasing affinity order become OR3, OR1 and OR2, determining a very significant difference in OR2 and OR3 regulatory behavior.

Cooperative effects between naturally spaced operator sequences has been well characterized costituting a solid guideline to individual or cooperative assembly with Constitutive Promoter Family Differential specificity, wide characterization and extended cooperative interactions make this operator set especially well suited to design complex regulatory interactions.

Sequence and Features