2v4n
From Proteopedia
Crystal structure of Salmonella typhimurium SurE at 1.7 angstrom resolution in orthorhombic form
Structural highlights
FunctionSURE_SALTY Nucleotidase with a broad substrate specificity as it can dephosphorylate various ribo- and deoxyribonucleoside 5'-monophosphates and ribonucleoside 3'-monophosphates with highest affinity to 3'-AMP. Also hydrolyzes polyphosphate (exopolyphosphatase activity) with the preference for short-chain-length substrates (P20-25). Might be involved in the regulation of dNTP and NTP pools, and in the turnover of 3'-mononucleotides produced by numerous intracellular RNases (T1, T2, and F) during the degradation of various RNAs.[HAMAP-Rule:MF_00060] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedSurE, the stationary-phase survival protein of Salmonella typhimurium, forms part of a stress survival operon regulated by the stationary-phase RNA polymerase alternative sigma factor. SurE is known to improve bacterial viability during stress conditions. It functions as a phosphatase specific to nucleoside monophosphates. In the present study we reported the X-ray crystal structure of SurE from Salmonella typhimurium. The protein crystallized in two forms: orthorhombic F222; and monoclinic C2. The two structures were determined to resolutions of 1.7 and 2.7 A, respectively. The protein exists as a domain-swapped dimer. The residue D230 is involved in several interactions that are probably crucial for domain swapping. A divalent metal ion is found at the active site of the enzyme, which is consistent with the divalent metal ion-dependent activity of the enzyme. Interactions of the conserved DD motif present at the N-terminus with the phosphate and the Mg(2+) present in the active site suggest that these residues play an important role in enzyme activity. The divalent metal ion specificity and the kinetic constants of SurE were determined using the generic phosphatase substrate para-nitrophenyl phosphate. The enzyme was inactive in the absence of divalent cations and was most active in the presence of Mg(2+). Thermal denaturation studies showed that S. typhimurium SurE is much less stable than its homologues and an attempt was made to understand the molecular basis of the lower thermal stability based on solvation free-energy. This is the first detailed crystal structure analysis of SurE from a mesophilic organism. Structural and functional studies on a mesophilic stationary phase survival protein (Sur E) from Salmonella typhimurium.,Pappachan A, Savithri HS, Murthy MR FEBS J. 2008 Dec;275(23):5855-64. PMID:19021761[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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