title: Structure of the Streptococcus agalactiae family II inorganic pyrophosphatase at 2.80 A resolution.
abstract: Streptococcus agalactiae, a prokaryote that causes infections in neonates and immunocompromised adults, has a serine/threonine protein kinase (STK) signalling cascade. The structure of one of the targets, a family II inorganic pyrophosphatase, has been solved by molecular replacement and refined at 2.80 A resolution to an R factor of 19.2% (R(free) = 26.7%). The two monomers in the asymmetric unit are related by a noncrystallographic twofold axis, but the biological dimer is formed by a crystallographic twofold. Each monomer contains the pyrophosphate analogue imidodiphosphate (PNP) and three metal ions per active site: two Mn(2+) ions in sites M1 and M2 and an Mg(2+) ion in site M3. The enzyme is in the closed conformation. Like other family II enzymes, the structure consists of two domains (residues 1-191 and 198-311), with the active site located between them. The conformation of Lys298 in the active site is different from those observed previously and it coordinates to the conserved DHH motif in a unique way. The structure suggests that Ser150, Ser194, Ser195 and Ser296 are the most likely targets for the Ser/Thr kinase and phosphatase because they are surface-accessible and either in the active site or in the hinge region between the two domains.
authors.affiliation: Institute of Biotechnology, University of Helsinki, PO Box 65, Helsinki, FIN-00014, Finland.
authors.forename: Mika K
authors.initials: MK
authors.lastname: Rantanen
authors.forename: Lari
authors.initials: L
authors.lastname: Lehtiö
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Rajagopal
authors.forename: Craig E
authors.initials: CE
authors.lastname: Rubens
authors.forename: Adrian
authors.initials: A
authors.lastname: Goldman
mesh_terms: D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D006801:Humans; D043564:Inorganic Pyrophosphatase / Q000737:chemistry*; D008958:Models, Molecular; D011487:Protein Conformation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry; D017434:Protein Structure, Tertiary; D012694:Serine / Q000737:chemistry; D055672:Static Electricity; D013292:Streptococcus agalactiae / Q000201:enzymology* / Q000472:pathogenicity
chemical_list: D012694:Serine; D017346:Protein Serine-Threonine Kinases; D043564:Inorganic Pyrophosphatase