FIG. 1.

Map of the glnK amtB region and construction of glnKY51F. To construct the glnKY51F mutation, the 5′ half of glnK was amplified with a mutagenic primer that contained the TAC → TTC base change encoding residue 51. The mutation of Y51 prevents uridylylation of the encoded protein and introduces a new EcoRI site. For selection of A. vinelandii transformants carrying the point mutation, a tetracycline resistance gene was introduced into the 5′ end of the downstream amtB gene carried on the plasmid. A. vinelandii mutants were selected on the basis of Tet^r and screened for sensitivity to vector-borne Amp^r. Of these, glnK was amplified and digested with EcoRI to identify mutants carrying the glnKY51F allele. The genetic structure of the stable gln-71 transformants MV577 and MV578 is shown. A, AvaI; E, EcoRI; H, HincII; Hd, HindIII; N, NspV; P PstI.