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An ATP‐binding cassette‐type cysteine transporter in Campylobacter jejuni inferred from the structure of an extracytoplasmic solute receptor protein
Author(s) -
Müller Axel,
Thomas Gavin H.,
Horler Richard,
Brannigan James A.,
Blagova Elena,
Levdikov Vladimir M.,
Fogg Mark J.,
Wilson Keith S.,
Wilkinson Anthony J.
Publication year - 2005
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2005.04691.x
Subject(s) - campylobacter jejuni , biology , cysteine , atp binding cassette transporter , transporter , biochemistry , amino acid , receptor , microbiology and biotechnology , gene , genetics , bacteria , enzyme
Summary Campylobacter jejuni is a Gram‐negative food‐borne pathogen associated with gastroenteritis in humans as well as cases of the autoimmune disease Guillain–Barré syndrome. C. jejuni is asaccharolytic because it lacks an active glycolytic pathway for the use of sugars as a carbon source. This suggests an increased reliance on amino acids as nutrients and indeed the genome sequence of this organism indicates the presence of a number of amino acid uptake systems. Cj0982, also known as CjaA, is a putative extracytoplasmic solute receptor for one such uptake system as well as a major surface antigen and vaccine candidate. The crystal structure of Cj0982 reveals a two‐domain protein with density in the enclosed cavity between the domains that clearly defines the presence of a bound cysteine ligand. Fluorescence titration experiments were used to demonstrate that Cj0982 binds cysteine tightly and specifically with a K d of ∼10 −7 M consistent with a role as a receptor for a high‐affinity transporter. These data imply that Cj0982 is the binding protein component of an ABC‐type cysteine transporter system and that cysteine uptake is important in the physiology of C. jejuni.