A computational study of lambda-lac mutants.

Full Abstract

We present a comprehensive, computational study of the properties of bacteriophage lambda mutants designed by Atsumi and Little (2006 Proc. Natl. Acad. Sci. 103 4558-63). These phages underwent a genetic reconstruction where Cro was replaced by a dimeric form of the Lac repressor. To clarify the theoretical characteristics of these mutants, we built a detailed thermodynamic model. The mutants all have a different genetic wiring than the wild-type lambda. One group lacks regulation of P(RM) by the lytic protein. These mutants only exhibit the lysogenic equilibrium, with no transiently active P(R). The other group lacks the negative feedback from CI. In this group, we identify a handful of bi-stable mutants, although the majority only exhibit the lysogenic equilibrium. The experimental identification of functional phages differs from our predictions. From a theoretical perspective, there is no reason why only 4 out of 900 mutants should be functional. The differences between theory and experiment can be explained in two ways. Either, the view of the lambda phage as a bi-stable system needs to be revised, or the mutants have in fact not undergone a modular replacement, as intended by Atsumi and Little, but constitute instead a wider systemic change.

Author information

Author/s: Werner, Maria (M); Aurell, Erik (E);

Affiliation: Department of Computational Biology, KTH-Royal Institute of Technology, Albanova University Center, SE-10691 Stockholm, Sweden. mariawer(-atsign-)kth.se

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: Physical biology (Phys Biol), published in England. (Language: eng)

Reference: 2009-; vol 6 (issue 4) : pp 46007

Dates: Created 2009/10/07; Completed 2009/11/02;

PMID: 19809101, status: MEDLINE (last retrieval date: 11/2/2009, IMS Date: )

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