A structural and biochemical basis for PAPS-independent sulfuryl transfer by aryl sulfotransferase from uropathogenic Escherichia coli |
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| Authors: | Goran Maloj?i? Robin L. Owen John P. A. Grimshaw Maurice S. Brozzo Hiang Dreher-Teo Rudi Glockshuber |
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| Affiliation: | aInstitute of Molecular Biology and Biophysics, ETH Zurich, CH-8093 Zurich, Switzerland; and ;bSwiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland |
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| Abstract: | Sulfotransferases are a versatile class of enzymes involved in numerous physiological processes. In mammals, adenosine 3′-phosphate-5′-phosphosulfate (PAPS) is the universal sulfuryl donor, and PAPS-dependent sulfurylation of small molecules, including hormones, sugars, and antibiotics, is a critical step in hepatic detoxification and extracellular signaling. In contrast, little is known about sulfotransferases in bacteria, which make use of sulfurylated molecules as mediators of cell–cell interactions and host–pathogen interactions. Bacterial arylsulfate sulfotransferases (also termed aryl sulfotransferases), in contrast to PAPS-dependent sulfotransferases, transfer sulfuryl groups exclusively among phenolic compounds in a PAPS-independent manner. Here, we report the crystal structure of the virulence factor arylsulfate sulfotransferase (ASST) from the prototypic, pyelonephritogenic Escherichia coli strain CFT073 at 2.0-Å resolution, and 2 catalytic intermediates, at 2.1-Å and 2.4-Å resolution, with substrates bound in the active site. ASST is one of the largest periplasmic enzymes and its 3D structure differs fundamentally from all other structurally characterized sulfotransferases. Each 63.8-kDa subunit of the ASST homodimer comprises a 6-bladed β-propeller domain and a C-terminal β-sandwich domain. The active sites of the dimer are situated at the center of the channel formed by each β-propeller and are defined by the side chains of His-252, His-356, Arg-374, and His-436. We show that ASST follows a ping-pong bi–bi reaction mechanism, in which the catalytic residue His-436 undergoes transient sulfurylation, a previously unreported covalent protein modification. The data provide a framework for understanding PAPS-independent sulfotransfer and a basis for drug design targeting this bacterial virulence factor. |
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| Keywords: | beta propeller crystal structure pyelonephritis uropathogenic Escherichia coli CFT073 periplasm |
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