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. 1994 Jan 15;13(2):367–372. doi: 10.1002/j.1460-2075.1994.tb06270.x

Mutagenesis supports water mediated recognition in the trp repressor-operator system.

A Joachimiak 1, T E Haran 1, P B Sigler 1
PMCID: PMC394817  PMID: 8313881

Abstract

High resolution crystallographic analysis of the trp repressor-operator complex indicates that the principal determinants of specificity are water mediated hydrogen bonds between the helix-turn-helix and the identity elements of the operator. One such hydration site involves a conserved G-C base pair (designated G6) six nucleotides away from the dyad which, if changed symmetrically to any other pair (e.g. G6-->A) reduces affinity to nonspecific levels. This same water site also contacts the conserved A5 which, if changed to G (mutation A5-->G), also diminishes affinity. The stereochemistry of the water mediated hydrogen bonding system predicts that the severe deterioration of in vitro binding caused by G6-->A should be reverted by a second deleterious mutation A5-->G. This proved to be the case. No other second mutation at conserved operator position 5 or 7 (flanking the G6-->A) reversed the effect of G6-->A.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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