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Crystal structure of the putative peptide‐binding protein AppA from Clostridium difficile
Author(s) -
Hughes Adam,
Wilson Samuel,
Dodson Eleanor J.,
Turkenburg Johan P.,
Wilkinson Anthony J.
Publication year - 2019
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 37
ISSN - 2053-230X
DOI - 10.1107/s2053230x1900178x
Subject(s) - oligopeptide , bacillus subtilis , peptide , biochemistry , transporter , biology , atp binding cassette transporter , chemistry , bacteria , gene , genetics
Peptides play an important signalling role in Bacillus subtilis , where their uptake by one of two ABC‐type oligopeptide transporters, Opp and App, is required for efficient sporulation. Homologues of these transporters in Clostridium difficile have been characterized, but their role, and hence that of peptides, in regulating sporulation in this organism is less clear. Here, the oligopeptide‐binding receptor proteins for these transporters, Cd AppA and Cd OppA, have been purified and partially characterized, and the crystal structure of Cd AppA has been determined in an open unliganded form. Peptide binding to either protein could not be observed in Thermofluor assays with a set of ten peptides of varying lengths and compositions. Re‐examination of the protein sequences together with structure comparisons prompts the proposal that Cd AppA is not a versatile peptide‐binding protein but instead may bind a restricted set of peptides. Meanwhile, Cd OppA is likely to be the receptor protein for a nickel‐uptake system.