Crystallization and preliminary X-ray analysis of betaC-S lyases from two oral Streptococci.

Hydrogen sulfide, which causes oral malodour, is generally produced from L-cysteine by the action of betaC-S lyase from oral bacteria. The betaC-S lyases from two oral bacteria, Streptococcus anginosus and S. gordonii, have been cloned, overproduced, purified and crystallized. X-ray diffraction data were collected from the two types of crystals using synchrotron radiation. The crystal of S. anginosus betaC-S lyase belonged to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 67.0, b = 111.1, c = 216.4 A, and the crystal of S. gordonii betaC-S lyase belonged to the same space group, with unit-cell parameters a = 58.0, b = 73.9. c = 187.6 A. The structures of the betaC-S lyases were solved by molecular-replacement techniques.