TY - JOUR
T1 - The "open" and "closed" x-ray structures of the type-C inorganic pyrophosphatases from Bacillus subtilis and Streptococcus gordonii
AU - Ahn, Shinbyoung
AU - Futterer, Klaus
AU - Young, Thomas
AU - White, Scott
AU - Milner, Andrew
AU - Konopka, Monika
AU - Ilias, Mohammad
PY - 2001/11/2
Y1 - 2001/11/2
N2 - Recently, a new class of soluble inorganic pyrophosphatase (type-C PPase) has been described that is not homologous in amino acid sequence or kinetic properties to the well-studied PPases (types A and B) found in many organisms from bacteria to humans and thought to be essential to the cell. Structural studies of the type-C PPases from Streptococcus gordonii and Bacillus subtilis reveal a homodimeric structure, with each polypeptide folding into two domains joined by a flexible hinge. The active site, formed at the interface between the N and C-terminal domains, binds two manganese ions approximately 3.6 A apart in a conformation resembling binuclear metal centres found in other hydrolytic enzymes. An activated water molecule bridging the two metal ions is likely poised for nucleophilic attack of the substrate. Importantly, the S. gordonii and B. subtilis enzymes have crystallised in strikingly different conformations. In both subunits of the S. gordonii crystal structure (1.5 A resolution) the C-terminal domain is positioned such that the active site is occluded, with a sulphate ion bound in the active site. In contrast, in the B. subtilis structure (3.0 A resolution) the C-terminal domain is rotated by about 90 degrees, leaving the active site wide open and accessible for substrate binding.
AB - Recently, a new class of soluble inorganic pyrophosphatase (type-C PPase) has been described that is not homologous in amino acid sequence or kinetic properties to the well-studied PPases (types A and B) found in many organisms from bacteria to humans and thought to be essential to the cell. Structural studies of the type-C PPases from Streptococcus gordonii and Bacillus subtilis reveal a homodimeric structure, with each polypeptide folding into two domains joined by a flexible hinge. The active site, formed at the interface between the N and C-terminal domains, binds two manganese ions approximately 3.6 A apart in a conformation resembling binuclear metal centres found in other hydrolytic enzymes. An activated water molecule bridging the two metal ions is likely poised for nucleophilic attack of the substrate. Importantly, the S. gordonii and B. subtilis enzymes have crystallised in strikingly different conformations. In both subunits of the S. gordonii crystal structure (1.5 A resolution) the C-terminal domain is positioned such that the active site is occluded, with a sulphate ion bound in the active site. In contrast, in the B. subtilis structure (3.0 A resolution) the C-terminal domain is rotated by about 90 degrees, leaving the active site wide open and accessible for substrate binding.
KW - X-ray crystallography
KW - enzyme mechanism
KW - phosphoryl transfer
KW - inorganic pyrophosphate
KW - binuclear manganese
UR - http://www.scopus.com/inward/record.url?scp=0035798394&partnerID=8YFLogxK
U2 - 10.1006/jmbi.2001.5070
DO - 10.1006/jmbi.2001.5070
M3 - Article
C2 - 11697905
VL - 313
SP - 797
EP - 811
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
ER -