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PMID:16818874

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Citation

Nelson, D, Schuch, R, Chahales, P, Zhu, S and Fischetti, VA (2006) PlyC: a multimeric bacteriophage lysin. Proc. Natl. Acad. Sci. U.S.A. 103:10765-70

Abstract

Lysins are murein hydrolases produced by bacteriophage that act on the bacterial host cell wall to release progeny phage. When added extrinsically in their purified form, these enzymes produce total lysis of susceptible Gram-positive bacteria within seconds, suggesting a unique antimicrobial strategy. All known Gram-positive lysins are produced as a single polypeptide containing a catalytic activity domain, which cleaves one of the four major peptidoglycan bonds, and a cell-wall-binding domain, which may bind a species-specific carbohydrate epitope in the cell wall. Here, we have cloned and expressed a unique lysin from the streptococcal bacteriophage C(1), termed PlyC. Molecular characterization of the plyC operon reveals that PlyC is, surprisingly, composed of two separate gene products, PlyCA and PlyCB. Based on biochemical and biophysical studies, the catalytically active PlyC holoenzyme is composed of eight PlyCB subunits for each PlyCA. Inhibitor studies predicted the presence of an active-site cysteine, and bioinformatic analysis revealed a cysteine, histidine-dependent amidohydrolase/peptidase domain within PlyCA. Point mutagenesis confirmed that PlyCA is responsible for the observed catalytic activity, and Cys-333 and His-420 are the active-site residues. PlyCB was found to self-assemble into an octamer, and this complex alone was able to direct streptococcal cell-wall-specific binding. Similar to no other proteins in sequence databases, PlyC defines a previously uncharacterized structural family of cell-wall hydrolases.

Links

PubMed PMC1487170 Online version:10.1073/pnas.0604521103

Keywords

Cell Wall/enzymology; Cell Wall/genetics; Enzymes/chemistry; Enzymes/genetics; Enzymes/physiology; Molecular Sequence Data; Mutagenesis, Site-Directed; N-Acetylmuramoyl-L-alanine Amidase/chemistry; N-Acetylmuramoyl-L-alanine Amidase/genetics; N-Acetylmuramoyl-L-alanine Amidase/physiology; Streptococcus Phages/chemistry; Streptococcus Phages/enzymology; Streptococcus Phages/genetics

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

9CAUD:Q7Y3F1

enables

GO:0005515: protein binding

ECO:0000353: physical interaction evidence used in manual assertion

UniProtKB:Q7Y3F3

F

Seeded From UniProt

complete

9CAUD:Q7Y3F3

enables

GO:0005515: protein binding

ECO:0000353: physical interaction evidence used in manual assertion

UniProtKB:Q7Y3F1

F

Seeded From UniProt

complete

9CAUD:Q7Y3F1

GO:0003796: lysozyme activity

ECO:0000315:

F

FIGURE 6 shows that PlyCA contains a functional Cysteine, Histidine-Dependent Amidohydrolase Peptidase (CHAP) Domain confirming it to have amidase activity, because it is able to cleave the amide bond between N-acetyl muramic acid and L-alanine in the streptococcal peptidoglycan (Fischetti et al., 1972).

complete
CACAO 12766

Notes

See also

References

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