Publication Date:
2014-04-03
Description:
Klebsiella pneumoniae PmrA is a polymyxin-resistance-associated response regulator. The C-terminal effector/DNA-binding domain of PmrA (PmrA C ) recognizes tandem imperfect repeat sequences on the promoters of genes to induce antimicrobial peptide resistance after phosphorylation and dimerization of its N-terminal receiver domain (PmrA N ). However, structural information concerning how phosphorylation of the response regulator enhances DNA recognition remains elusive. To gain insights, we determined the nuclear magnetic resonance solution structure of PmrA C and characterized the interactions between PmrA C or BeF 3 – -activated full-length PmrA (PmrA F ) and two DNA sequences from the pbgP promoter of K. pneumoniae . We showed that PmrA C binds to the PmrA box, which was verified to contain two half-sites, 5'-CTTAAT-3' and 5'-CCTAAG-3', in a head-to-tail fashion with much stronger affinity to the first than the second site without cooperativity. The structural basis for the PmrA C –DNA complex was investigated using HADDOCK docking and confirmed by paramagnetic relaxation enhancement. Unlike PmrA C , PmrA F recognizes the two sites simultaneously and specifically. In the PmrA F –DNA complex, PmrA N may maintain an activated homodimeric conformation analogous to that in the free form and the interactions between two PmrA C molecules aid in bending and binding of the DNA duplex for transcription activation.
Print ISSN:
0305-1048
Electronic ISSN:
1362-4962
Topics:
Biology
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