Restriction map of a 17-kb insert DNA in lambda clone 311 containing H. pseudoflava CO-DH genes. EcoRI (E), SmaI (M), and SalI (S) were used for restriction mapping. The probe binding site, a 1.5-kb SalI fragment in pBKS2, and a 3.5-kb SmaI fragment in pBKX1 are indicated under the map. ORFs for large (cutL), medium (cutM), and small (cutS) subunits of CO-DH are shown by arrows.