Open AccessStructure of the Streptococcus agalactiae family II inorganic pyrophosphatase at 2.80 Å resolution
Author(s) -
Rantanen Mika K.,
Lehtiö Lari,
Rajagopal Lakshmi,
Rubens Craig E.,
Goldman Adrian
Publication year - 2007
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
ISSN - 1399-0047
DOI - 10.1107/s0907444907019695
Subject(s) - active site , dimer , chemistry , hydrolase , serine , threonine , molecular replacement , stereochemistry , crystallography , monomer , phosphatase , enzyme , binding site , streptococcus agalactiae , biochemistry , biology , bacteria , streptococcus , genetics , organic chemistry , polymer
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 Å 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.