A structural and biochemical basis for PAPS-independent sulfuryl transfer by aryl sulfotransferase from uropathogenic Escherichia coli.
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-A resolution, and 2 catalytic intermediates, at 2.1-A and 2.4-A 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 beta-propeller domain and a C-terminal beta-sandwich domain. The active sites of the dimer are situated at the center of the channel formed by each beta-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.
Malojcić
Goran
G
Institute of Molecular Biology and Biophysics, ETH Zurich, CH-8093 Zurich, Switzerland. goran@mol.biol.ethz.ch
Owen
Robin L
RL
Grimshaw
John P A
JP
Brozzo
Maurice S
MS
Dreher-Teo
Hiang
H
Glockshuber
Rudi
R
D000818:Animals; D015239:Arylsulfotransferase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020134:Catalytic Domain; D003461:Crystallography; D019281:Dimerization; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008322:Mammals; D016297:Mutagenesis, Site-Directed; D010724:Phosphoadenosine Phosphosulfate / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011704:Pyelonephritis / Q000382:microbiology; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D037521:Virulence Factors / Q000737:chemistry / Q000378:metabolism
D029968:Escherichia coli Proteins; D037521:Virulence Factors; D010724:Phosphoadenosine Phosphosulfate; D015239:Arylsulfotransferase; C090707:arylsulfate sulfotransferase