title: An atypical segment swap in the DN and DC domains of the Acr_tran family resistance-nodulation-cell division pump.
abstract: Domain/segment swapping is an exchange of equivalent secondary structure element(s) among two or more protein domains resulting in the reconstitution of the original fold while simultaneously causing oligomerization. Here we report an example of the outer membrane factor docking region of the Acr_tran family (PF00873) resistance-nodulation-cell division pump, in which a swapped, misfolded state, of the ferredoxin-like fold of the DN and DC domains, effectuates oligomerization. The atypical segment swap and the associated displacement of a region of the ferredoxin-like fold leads to a topology that is distinct from the original fold. To our knowledge, such segment swaps and associated fold change are rare. This exemplifies the role of functional constraints including oligomerization that determine the interplay between sequence and the three-dimensional structure of proteins.
authors.affiliation: CSIR-Institute of Microbial Technology (IMTECH), Sector 39-A, Chandigarh 160036, India.
authors.forename: Giriraj
authors.initials: G
authors.lastname: Acharya
authors.affiliation: CSIR-Institute of Microbial Technology (IMTECH), Sector 39-A, Chandigarh 160036, India.
authors.forename: Gurmeet
authors.initials: G
authors.lastname: Kaur
authors.affiliation: CSIR-Institute of Microbial Technology (IMTECH), Sector 39-A, Chandigarh 160036, India. Electronic address: krishna@imtech.res.in.
authors.forename: Srikrishna
authors.initials: S
authors.lastname: Subramanian
mesh_terms: D000595:Amino Acid Sequence / Q000235:genetics*; D002455:Cell Division; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000648:ultrastructure; D008958:Models, Molecular; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000737:chemistry* / Q000648:ultrastructure; D000072417:Protein Domains; D017510:Protein Folding; D055503:Protein Multimerization / Q000235:genetics; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry* / Q000648:ultrastructure; D017386:Sequence Homology, Amino Acid
chemical_list: D029968:Escherichia coli Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D011506:Proteins; C083496:AcrB protein, E coli
keywords: Domain duplication; Domain swapping; Fold change; Membrane proteins; Metamorphic proteins; RND pump