Functional analysis of the lysis genes of Staphylococcus aureus phage P68 in Escherichia coli.
Double-stranded DNA phages of both Gram-positive and Gram-negative bacteria typically use a holin-endolysin system to achieve lysis of their host. In this study, the lysis genes of Staphylococcus aureus phage P68 were characterized. P68 gene lys16 was shown to encode a cell-wall-degrading enzyme, which causes cell lysis when externally added to clinical isolates of S. aureus. Another gene, hol15, was identified embedded in the -1 reading frame at the 3' end of lys16. The deduced Hol15 protein has three putative transmembrane domains, and thus resembles class I holins. An additional candidate holin gene, hol12, was found downstream of the endolysin gene lys16 based on two predicted transmembrane domains of the encoded protein, which is a typical trait of class II holins. The synthesis of either Hol12 or Hol15 resulted in growth retardation of Escherichia coli, and both hol15 and hol12 were able to complement a phage lambda Sam mutation. The hol15 gene has a dual start motif beginning with the codons Met1-Lys2-Met3.... Evidence is presented that the hol15 gene encodes a lysis inhibitor (anti-holin) and a lysis effector (actual holin). As depolarization of the membrane converted the anti-holin to a functional holin, these studies suggested that hol15 functions as a typical dual start motif class I holin. The unusual arrangement of the P68 lysis genes is discussed.
Max F. Perutz Laboratories, Department of Microbiology and Immunobiology, University Departments at the Vienna Biocenter, Dr Bohrgasse 9/4, 1030 Vienna, Austria.
Marian
M
Takáč
Max F. Perutz Laboratories, Department of Microbiology and Immunobiology, University Departments at the Vienna Biocenter, Dr Bohrgasse 9/4, 1030 Vienna, Austria.
Angela
A
Witte
Max F. Perutz Laboratories, Department of Microbiology and Immunobiology, University Departments at the Vienna Biocenter, Dr Bohrgasse 9/4, 1030 Vienna, Austria.
Udo
U
Bläsi
D000595:Amino Acid Sequence; D001433:Bacteriolysis / Q000502:physiology*; D004279:DNA, Viral / Q000235:genetics; D004926:Escherichia coli / Q000502:physiology / Q000821:virology*; D008969:Molecular Sequence Data; D013204:Staphylococcus Phages / Q000201:enzymology / Q000235:genetics* / Q000502:physiology; D013211:Staphylococcus aureus / Q000821:virology*; D014764:Viral Proteins / Q000235:genetics*
D004279:DNA, Viral; D014764:Viral Proteins