Functional analysis of different domains of Cpe^Sc and its homologues during clavulanic acid production in <i>S</i>. <i>clavuligerus</i>.

(A and B) LC-MS analysis of 96 hour SA culture supernatants after imidazole derivatization using the ammonium bicarbonate buffer system [38]. Cultures of wt S. clavuligerus or the Δcpe-INF mutant expressing Cpe from S. clavuligerus (pHM:cpeSc), S. flavogriseus (pHM:cpeSf), S. jumonjinensis/S. katsurahamanus (pHM:cpeSj/Sk) or the C-terminal domain of CpeSc (pHM:cpeCt) were used in the analysis. (A) Liquid chromatography profiles showing the elution of the peaks corresponding to imidazole-derivatized clavulanic acid (indicated by the star symbol). (B) Mass spectra of the major peaks corresponding imidazole-derivatized clavulanic acid [M+H]+ (m/z = 224) and the fragmented product [M-imidazole]+ (m/z = 156), which were only detected in supernatants from clavulanic acid producing strains shown in (A).