Characterization of the catalytic activity of the gamma-phage lysin, PlyG, specific for Bacillus anthracis.
Bacillus anthracis causes anthrax, a lethal disease affecting humans that has attracted attention due to its bioterrorism potential. PlyG is a lysin of gamma-phage, which specifically infects B. anthracis and lyses its cell wall. PlyG contains a T7 lysozyme-like amidase domain, which appears to be the catalytic domain, in the N-terminal region and has a high degree of sequence similarity with PlyL, which is an N-acetylmuramoyl-l-alanine amidase encoded by the B. anthracis genome. Here, we demonstrated that two amino acid residues of PlyG, H29 and E90, are necessary for its catalytic activity in B. anthracis. These residues are structurally analogous to residues whose mutation in T7 lysozyme abolished its catalytic activity. A C-terminal deletion mutant of PlyG lacking the core sequence for binding to B. anthracis showed completely abolished binding activity, unlike PlyL, despite high sequence similarity with PlyL in the N-terminal region. This suggests that the C-terminal binding domain, as well as the N-terminal catalytic domain, is essential for the catalytic activity of PlyG. Our observations provide new insights into the mechanism of specific catalysis of PlyG in B. anthracis and may contribute to the establishment of new methods for anthrax therapy.
Kikkawa
Hitomi S
HS
Third Department of Forensic Science, National Research Institute of Police Science, Kashiwa, Japan.
Ueda
Takuya
T
Suzuki
Shin-Ichi
S
Yasuda
Jiro
J
D000581:Amidohydrolases / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D017103:Bacillus Phages / Q000201:enzymology*; D001408:Bacillus anthracis / Q000821:virology*; D001426:Bacterial Proteins / Q000235:genetics; D020134:Catalytic Domain; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017384:Sequence Deletion; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D014764:Viral Proteins; C465450:PlyG lysin, gamma phage; D000581:Amidohydrolases; C506058:PlyL protein, Bacillus anthracis; D009238:N-Acetylmuramoyl-L-alanine Amidase; C019665:amidase