GONUTS has been updated to MW1.31 Most things seem to be working but be sure to report problems.
PMID:10419939
| Citation |
Loessner, MJ, Gaeng, S and Scherer, S (1999) Evidence for a holin-like protein gene fully embedded out of frame in the endolysin gene of Staphylococcus aureus bacteriophage 187. J. Bacteriol. 181:4452-60 |
|---|---|
| Abstract |
We have cloned, sequenced, and characterized the genes encoding the lytic system of the unique Staphylococcus aureus phage 187. The endolysin gene ply187 encodes a large cell wall-lytic enzyme (71.6 kDa). The catalytic site, responsible for the hydrolysis of staphylococcal peptidoglycan, was mapped to the N-terminal domain of the protein by the expression of defined ply187 domains. This enzymatically active N terminus showed convincing amino acid sequence homology to an N-acetylmuramoyl-L-alanine amidase, whereas the C-terminal part, whose function is unknown, revealed striking relatedness to major staphylococcal autolysins. An additional reading frame was identified entirely embedded out of frame (+1) within the 5' region of ply187 and was shown to encode a small, hydrophobic protein of holin-like function. The hol187 gene features a dual-start motif, possibly enabling the synthesis of two products of different lengths (57 and 55 amino acids, respectively). Overproduction of Hol187 in Escherichia coli resulted in growth retardation, leakiness of the cytoplasmic membrane, and loss of de novo ATP synthesis. Compared to other holins identified to date, Hol187 completely lacks the highly charged C terminus. The secondary structure of the polypeptide is predicted to consist of two small, antiparallel, hydrophobic, transmembrane helices. These are supposed to be essential for integration into the membrane, since site-specific introduction of negatively charged amino acids into the first transmembrane domain (V7D G8D) completely abolished the function of the Hol187 polypeptide. With antibodies raised against a synthetic 18-mer peptide representing a central part of the protein, it was possible to detect Hol187 in the cytoplasmic membrane of phage-infected S. aureus cells. An important indication that the protein actually functions as a holin in vivo was that the gene (but not the V7D G8D mutation) was able to complement a phage lambda Sam mutation in a nonsuppressing E. coli HB101 background. Plaque formation by lambdagt11::hol187 indicated that both phage genes have analogous functions. The data presented here indicate that a putative holin is encoded on a different reading frame within the enzymatically active domain of ply187 and that the holin is synthesized during the late stage of phage infection and found in the cytoplasmic membrane, where it causes membrane lesions which are thought to enable access of Ply187 to the peptidoglycan of phage-infected Staphylococcus cells. |
| Links | |
| Keywords |
Amino Acid Sequence; Base Sequence; Cloning, Molecular; DNA, Viral/genetics; Endopeptidases/genetics; Escherichia coli; Kinetics; Membrane Proteins/chemistry; Membrane Proteins/genetics; Membrane Proteins/metabolism; Molecular Sequence Data; Polymerase Chain Reaction; Protein Conformation; Recombinant Fusion Proteins/biosynthesis; Recombinant Fusion Proteins/chemistry; Recombinant Fusion Proteins/metabolism; Sequence Alignment; Sequence Homology, Amino Acid; Staphylococcus Phages/enzymology; Staphylococcus Phages/genetics; Staphylococcus Phages/physiology; Staphylococcus aureus/virology; Viral Proteins; beta-Galactosidase/genetics |
Significance
Annotations
| Gene product | Qualifier | GO Term | Evidence Code | with/from | Aspect | Extension | Notes | Status |
|---|---|---|---|---|---|---|---|---|
| GO:0016787: hydrolase activity |
ECO:0000314: |
F |
Expression of a fragment ply187 gave only 297 aa chain which represent only 47% of the protein entire length. Individual lysis activity only different fragments of the gene were performed and showed that peptidoglycan hydrolyzing activity were highest at N termites of the protein. (Shown in figure 3) |
complete | ||||
| GO:0034290: holin activity |
ECO:0000315: |
F |
Figure 1B and 4 showed the present of Ply-Holin protein embedded at beginning of N terminus of this whole gene. The graphs showed the protein as hydrophobic beta turn linker, dual start motif stretch of hydrophobic amino acid. When tested this holin sequence in Ecoli, it caused well wall degradation. Mutation at at cys residue to lysine caused less damage to the cell. |
complete | ||||
| GO:0034290: holin activity |
ECO:0000317: |
UniProtKB:9CAUD:O56785
|
F |
Figure 1B in this reference showed that this entire gene was embedded within ply 187 gene by changing the reading frame near N terminus of ply187. |
complete | |||
| GO:0020002: host cell plasma membrane |
ECO:0000314: |
C |
Figure 5: Hol187 is found in the cytoplasmic membrane of phage-infected cells. Immunoblotting with specific peptide antibodies against Hol187 showed Hol187 is synthesized in S. aureus host cells when infected with phage 187. Immunoblotting enabled the detection of Hol187 in membrane fractions of these cells. Uninfected control cells did not have a signal. |
complete | ||||
Notes
See also
References
See Help:References for how to manage references in GONUTS.
