SCAN:Monofunctional transglycosylases are not essential for Staphylococcus aureus cell wall synthesis
Patricia Reed Post-Doctoral at Bacterial Cell Biology Laboratory
| When |
22 Jun, 2011
from
12:00 pm to 01:00 pm |
|---|---|
| Where | Auditorium |
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ITQB- SCAN Seminar
Title: Monofunctional transglycosylases are not essential for Staphylococcus aureus cell wall synthesis
Speaker: Patricia Reed
From: Bacterial Cell Biology Laboratory
Abstract:
Polymerisation of peptidoglycan is the result of two types of enzymatic activities: transglycosylation, the formation of linear glycan chains, and transpeptidation, the formation of peptide cross-bridges between the glycan strands. S. aureus has four penicillin binding proteins (PBPs 1-4) with transpeptidation activity, one of which, PBP2 is a bi-functional enzyme also capable of catalysing transglycosylation reactions. Additionally, two monofunctional transglycosylases have been reported in S. aureus: MGT that has been shown to have in vitro transglycosylase activity, and a second putative transglycosylase, SgtA, identified only by sequence analysis. We have now shown that purified SgtA has in vitro transglycosylase activity and that both MGT and SgtA are not essential in S. aureus. However, in the absence of PBP2 transglycosylase activity, MGT but not SgtA becomes essential for cell viability. This indicates that S. aureus cells require one transglycosylase for survival, either PBP2 or MGT, both of which can act as the sole synthetic transglycosylase for cell wall synthesis. We have also shown that both MGT and SgtA interact with PBP2 and other enzymes involved in cell wall synthesis in a bacterial two-hybrid assay, suggesting that these enzymes may work in collaboration as part of a larger, yet uncharacterised cell wall synthetic complex.
