FIG. 3.

Protein levels for the key enzymes of penicillin biosynthesis as a function of the genomic copy number of the penicillin gene cluster. (A) Relative levels of the enzymes ACVS, AT, IPNS, and PCL, as determined by Western blotting and immunostaining using specific polyclonal antibodies. Samples used for Western blotting were normalized with antibodies directed at elongation factor EF1-α. Strains analyzed are as follows: lane 1, DS47274 (1 copy); lane 2, DS47273 (3 copies); lane 3, DS47276 (4 copies); lane 4, DS47272 (7 copies); lane 5, DS50652 (cluster free); lane 6, Wisconsin54-1255; and lane 7, DS17690 (8 copies). (B) Quantitation of the protein levels as a function of the biosynthetic gene cluster number. Protein levels of ACVS (closed squares), IPNS (closed triangles), AT (open squares), and PCL (open triangles). The protein level in the single-copy strain DS47274 was set at 12.5% to relate to the 8-fold-increased copy number of the P. chrysogenum DS17690 strain.