%A Gurmeet Kaur
%A Srikrishna Subramanian
%O Copyright of this article belongs to Elsevier Science.
%J Journal of structural biology
%T The Ku-Mar zinc finger: A segment-swapped zinc ribbon in MarR-like transcription regulators related to the Ku bridge.
%X Two putative oxidative-stress sensor proteins from Pseudomonas aeruginosa, PA1607 and PA1374, belong to the MarR family of transcription regulators and possess a unique mode of dimerization. In these proteins, in addition to the ?-helices involved in dimerization, inter-subunit contacts are strengthened by additional C-terminal ?-strands. Using sequence and structure analysis we show that these ?-strands constitute a novel segment-swapped zinc ribbon domain. We detect the presence of the zinc ribbon domain in MarR proteins from many bacterial homologs. While the metal-chelating residues of the zinc ribbons are absent in most members of this family, we could however identify several species of Proteobacteria, Actinobacteria and Firmicutes that possess intact zinc-chelating sites. Conservation pattern of metal-chelating residues together with the extensive structural resemblance to zinc ribbons, in particular to the bridge-region of the dsDNA break repair protein Ku, suggests that the C-terminal ?-rich region of these proteins is a zinc ribbon. Sequence analysis also supports a distant evolutionary connection between the zinc ribbons of the MarR and Ku families. However, unlike Ku where the segment-swapped zinc ribbons play a role in DNA-binding and obligate dimerization, their primary role in MarR appears to be in dimerization and strengthening of inter-subunit contacts.
%N 3
%K Zinc ribbon; 
Segment-swapping; 
DNA-binding proteins; 
Helix-turn-helix domain; 
Dimerization; 
Multidrug resistance

%P 281-9
%V 191
%D 2015
%I Elsevier Science
%L open1761