Structure-based analysis of CysZ-mediated cellular uptake of sulfate

• Main Authors: Zahra Assur Sanghai, Qun Liu, Oliver B Clarke, Meagan Belcher-Dufrisne, Pattama Wiriyasermkul, M Hunter Giese, Edgar Leal-Pinto, Brian Kloss, Shantelle Tabuso, James Love, Marco Punta, Surajit Banerjee, Kanagalaghatta R Rajashankar, Burkhard Rost, Diomedes Logothetis, Matthias Quick, Wayne A Hendrickson, Filippo Mancia
• Format: Article
• Language: English
• Published: eLife Sciences Publications Ltd 2018-05-01
• Series: eLife
• Subjects: Pseudomonas denitrificans; Pseudomonas fragi; Idiomarina loihiensis
• Online Access: https://elifesciences.org/articles/27829

Sulfur, most abundantly found in the environment as sulfate (SO42-), is an essential element in metabolites required by all living cells, including amino acids, co-factors and vitamins. However, current understanding of the cellular delivery of SO42- at the molecular level is limited. CysZ has been described as a SO42- permease, but its sequence family is without known structural precedent. Based on crystallographic structure information, SO42- binding and flux experiments, we provide insight into the molecular mechanism of CysZ-mediated translocation of SO42- across membranes. CysZ structures from three different bacterial species display a hitherto unknown fold and have subunits organized with inverted transmembrane topology. CysZ from Pseudomonas denitrificans assembles as a trimer of antiparallel dimers and the CysZ structures from two other species recapitulate dimers from this assembly. Mutational studies highlight the functional relevance of conserved CysZ residues.