1RZS : Solution structure of P22 Cro

  • Matthew Hj Cordes (Contributor)
  • Tracey Newlove (Contributor)
  • Jay H. Konieczka (Contributor)



Experimental Technique/Method:SOLUTION NMR
Release Date:2004-06-01
Deposition Date:2003-12-28
Revision Date:2008-04-29#2011-07-13
Molecular Weight:6837.77
Macromolecule Type:Protein
Residue Count:61
Atom Site Count:482

We report the solution structure of the Cro protein from bacteriophage P22. Comparisons of its sequence and structure to those of lambda Cro strongly suggest an alpha-to-beta secondary structure switching event during Cro evolution. The folds of P22 Cro and lambda Cro share a three alpha helix fragment comprising the N-terminal half of the domain. However, P22 Cro's C terminus folds as two helices, while lambda Cro's folds as a beta hairpin. The all-alpha fold found for P22 Cro appears to be ancestral, since it also occurs in cI proteins, which are anciently duplicated paralogues of Cro. PSI-BLAST and transitive homology analyses strongly suggest that the sequences of P22 Cro and lambda Cro are globally homologous despite encoding different folds. The alpha+beta fold of lambda Cro therefore likely evolved from its all-alpha ancestor by homologous secondary structure switching, rather than by nonhomologous replacement of both sequence and structure.
Date made available2004

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