Modular organization of the lytic enzymes of Streptococcus pneumoniae and its bacteriophages

Gene. 1990 Jan 31;86(1):81-8. doi: 10.1016/0378-1119(90)90116-9.


The nucleotide sequences of genes cpl7 and cpl9 of the Streptococcus pneumoniae bacteriophages Cp-7 and Cp-9, encoding the muramidases CPL-7 and CPL-9, respectively, have been determined. The N-terminal domains of CPL-7 and CPL-9 were virtually identical to that previously reported for the CPL-1 muramidase. The C-terminal domain of the CPL-7 muramidase, however, was different from those of the host amidase and the phage Cp-1 and Cp-9 lysozymes. Whereas all enzymes studied are characterized by repeated sequences at their C termini, the repeat-unit lengths are 20 amino acids (aa) in CPL-1, CPL-9 and in the host amidase, but 48 aa in CPL-7. Six repeated sequences represent the C-terminal domains of CPL-1, CPL-9 and the host amidase, and 2.8 perfect tandem repetitions that of CPL-7. The peculiar characteristics of the structure of CPL-7 muramidase correlate with its biochemical and biological properties. Whereas CPL-1, CPL-9 and the pneumococcal amidase strictly depend on the presence of choline-containing cell walls for activity, CPL-7 is able to degrade cell walls containing either choline or ethanolamine. These results support the previously postulated role for the C-terminal domain of these lytic enzymes in substrate recognition and provide further experimental evidence supporting the notion that the proteins have evolved by an exchange of modular units.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacteriophages / enzymology
  • Bacteriophages / genetics*
  • Base Sequence
  • Blotting, Southern
  • Cloning, Molecular
  • Genes, Viral
  • Molecular Sequence Data
  • Muramidase / genetics*
  • Muramidase / metabolism
  • Restriction Mapping
  • Streptococcus pneumoniae / enzymology*
  • Streptococcus pneumoniae / genetics
  • Substrate Specificity
  • Viral Structural Proteins / genetics


  • Viral Structural Proteins
  • Muramidase

Associated data

  • GENBANK/M34779
  • GENBANK/M34780