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PMID:17526702
| Citation |
Kohler, PL, Hamilton, HL, Cloud-Hansen, K and Dillard, JP (2007) AtlA functions as a peptidoglycan lytic transglycosylase in the Neisseria gonorrhoeae type IV secretion system. J. Bacteriol. 189:5421-8 |
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| Abstract |
Type IV secretion systems require peptidoglycan lytic transglycosylases for efficient secretion, but the function of these enzymes is not clear. The type IV secretion system gene cluster of Neisseria gonorrhoeae encodes two peptidoglycan transglycosylase homologues. One, LtgX, is similar to peptidoglycan transglycosylases from other type IV secretion systems. The other, AtlA, is similar to endolysins from bacteriophages and is not similar to any described type IV secretion component. We characterized the enzymatic function of AtlA in order to examine its role in the type IV secretion system. Purified AtlA was found to degrade macromolecular peptidoglycan and to produce 1,6-anhydro peptidoglycan monomers, characteristic of lytic transglycosylase activity. We found that AtlA can functionally replace the lambda endolysin to lyse Escherichia coli. In contrast, a sensitive measure of lysis demonstrated that AtlA does not lyse gonococci expressing it or gonococci cocultured with an AtlA-expressing strain. The gonococcal type IV secretion system secretes DNA during growth. A deletion of ltgX or a substitution in the putative active site of AtlA severely decreased DNA secretion. These results indicate that AtlA and LtgX are actively involved in type IV secretion and that AtlA is not involved in lysis of gonococci to release DNA. This is the first demonstration that a type IV secretion peptidoglycanase has lytic transglycosylase activity. These data show that AtlA plays a role in type IV secretion of DNA that requires peptidoglycan breakdown without cell lysis. |
| Links |
PubMed PMC1951824 Online version:10.1128/JB.00531-07 |
| Keywords |
Bacterial Proteins/genetics; Bacterial Proteins/isolation & purification; Bacterial Proteins/metabolism; Bacteriolysis; Bacteriophage lambda/growth & development; Biological Transport/physiology; DNA, Bacterial/metabolism; Escherichia coli/genetics; Escherichia coli/virology; Mutation; Neisseria gonorrhoeae/enzymology; Neisseria gonorrhoeae/genetics; Peptidoglycan/metabolism; Peptidoglycan Glycosyltransferase/genetics; Peptidoglycan Glycosyltransferase/isolation & purification; Peptidoglycan Glycosyltransferase/metabolism |
Significance
Annotations
| Gene product | Qualifier | GO Term | Evidence Code | with/from | Aspect | Extension | Notes | Status |
|---|---|---|---|---|---|---|---|---|
| GO:0008933: lytic transglycosylase activity |
ECO:0000314: |
F |
Figure 2 HPLC Analysis to compare Atla-generated PG monomers, PG monomoers generated by hen egg white lysozyme and 1,6-anhydro PG monomers released by growing gonococci. PG monomers liberated by AtlA activity consisted primarily of 1,6-anhydro disaccharide tetrapeptide PG monomers, and a small portion of the released monomers consisted of the 1,6-anhydro disaccharide tripeptide. These data demonstrate that AtlA functions as a lytic transglycosylase. |
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Notes
See also
References
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