Table 3.

Activation of histidase formation and repression of GDH formation in vivo by modified forms of NAC

NAC source and strainaPlasmidbNAC productcSp actd of:
HistidaseGDH
E. coli
 KC2725NoneNone31413
 KC3568pCB774NACE41546
 KC3210pCB594MBP-NACE34435
 KC3555pCB771NACE-his689021
 KC3973pCB941NACE100-his642354
K. aerogenes
 KC3572pCB778NACK52059
 KC3981pCB606MBP-NACK37417
 KC3578pCB781NACK-his665035
 KC3580pCB782NACK-DFGRSGHDTSL72032
 KC3615pCB800NACK120-his6295NDe
 KC3591pCB788NACK100-his645335
  • a All strains are derived from K. aerogenes KC2725 (nac-203::Tn5-131), grown in glucose minimal medium to mid-log phase, and assayed as previously described (12). IPTG (0.5 mM) was included for strain KC3981 to guarantee expression from the pMalC2 vector.

  • b All plasmids except pCB594 and PCB606 were derived from pGD103 as described in Materials and Methods. Plasmids pCB594 and pCB606 were derived from pMalC2.

  • c The code is described in detail in the text. Subscripts indicate derivation from E. coli (E) or K. aerogenes (K). MBP indicates MBP fused to the N terminus of NAC. his6 indicates six histidine residues added to the C terminus. DFGRSGHTDSL indicates fusion of 11 amino acids to the C terminus of NAC (amino acids are indicated by the one-letter code). NAC100 and NAC120 indicate that only the first 100 or 120 amino acids of NAC were present.

  • d Specific activity is reported as nanomoles per minute per milligram of cell protein.

  • e ND, not determined.