Crystallization and preliminary X-ray crystallographic studies of succinic semialdehyde dehydrogenase from Streptococcus pyogenes

Abstract

Succinic semialdehyde dehydrogenase (SSADH) plays a critical role in the metabolism of the inhibitory neurotransmitter ?-aminobutyric acid (GABA) and catalyzes the NAD(P)+-coupled oxidation of succinic semialdehyde (SSA) to succinic acid (SA). SSADH from Streptococcus pyogenes has been purified and crystallized as the apoenzyme and in a complex with NAD+. The crystals of native and NAD+-complexed SSADH diffracted to resolutions of 1.6 and 1.7 angstrom, respectively, using a synchrotron-radiation source. Both crystals belonged to the orthorhombic space group P212121, with unit-cell parameters a = 93.3, b = 100.3, c = 105.1 angstrom for the native crystal and a = 93.3, b = 100.3, c = 105.0 angstrom for the complex crystal. Preliminary molecular replacement confirmed the presence of one dimer in both crystals, corresponding to a Matthews coefficient (VM) of 2.37 angstrom 3 Da-1 and a solvent content of 48.0%.