TABLE 3.

Summary of library construction and DRTA results

Chromosomal DNA sourceaEnzymebVectorcInsert size (kb)CFU screeneddDRTA-positive cloneseClones identifiedf (no.)
C7(−)Sau3AIpKSX650.5-310,00022CD-1 (4), CD-2 (4), CD-3, CD-4, CD-sid (2), IRP3, IRP1 (2), NH (2), NF (5)
MspIpCM2.63-73,50013CD-7-4 (2), CD-40, CD-frg, IRP1 (4), IRP2 (2), NH (2), NF (1)
1716Sau3AIpKSX650.5-310,00023CD-1, CD-3 (3), CD-7-4, CD-20, CD-40 (4), CD-50, CD-sid, IRP4, hmuO, tox (4), NF (5)
  • a Chromosomal DNA from the indicated C. diphtheriae strain was used for library construction.

  • b Restriction endonuclease used in the construction of the library.

  • c Plasmid vector used for library construction.

  • d Total number of CFU that were screened for the library.

  • e Total number of DRTA-positive clones (blue colonies) that were identified in the library.

  • f Numbers in parentheses indicate the number of additional or duplicate clones that were identified. NH, DNA sequence of the insert had no (or minimal) homology to the genome sequence of C. diphtheriae strain NCTC 13129 or to any sequences in GenBank. NF, a DtxR binding site was not found within 7 kb of the tagged sequence on these DRTA-positive clones.