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Accessibility to Peptidoglycan Is Important for the Recognition of Gram-Positive Bacteria in Drosophila
Publication . Vaz, Filipa; Kounatidis, Ilias; Covas, Gonçalo; Parton, Richard M.; Harkiolaki, Maria; Davis, Ilan; Filipe, Sergio Raposo; Ligoxygakis, Petros; Instituto de Tecnologia Química e Biológica António Xavier (ITQB); DCV - Departamento de Ciências da Vida; UCIBIO - Applied Molecular Biosciences Unit; Elsevier
In Drosophila, it is thought that peptidoglycan recognition proteins (PGRPs) SA and LC structurally discriminate between bacterial peptidoglycans with lysine (Lys) or diaminopimelic (DAP) acid, respectively, thus inducing differential antimicrobial transcription response. Here, we find that accessibility to PG at the cell wall plays a central role in immunity to infection. When wall teichoic acids (WTAs) are genetically removed from S. aureus (Lys type) and Bacillus subtilis (DAP type), thus increasing accessibility, the binding of both PGRPs to either bacterium is increased. PGRP-SA and -LC double mutant flies are more susceptible to infection with both WTA-less bacteria. In addition, WTA-less bacteria grow better in PGRP-SA/-LC double mutant flies. Finally, infection with WTA-less bacteria abolishes any differential activation of downstream antimicrobial transcription. Our results indicate that accessibility to cell wall PG is a major factor in PGRP-mediated immunity and may be the cause for discrimination between classes of pathogens. It is widely believed that preference in recognition of structural features of bacterial peptidoglycan (PG) drives specificity in the Drosophila antibacterial response. Vaz et al. challenge this dogma by showing that accessibility to PG plays a central role in bacterial sensing and that structural discrimination is much less stringent than previously thought.
Bacteria present mechanisms to evade cellular and humoral responses mediated through peptidoglycan recognition by PGRP-SA and PGRP-LC
Publication . Vaz, Filipa Baltazar da Costa; Filipe, Sérgio Raposo
The Host presents different innate immune components to fight
bacterial infections, most of which are evolutionary conserved strategies.
Conversely, Bacteria present numerous mechanisms of virulence and
evasion, transversal to different bacterial species, that confer resistance or
subvert the activity of the Host components. This thesis presents a study
on how the Host perceives the Bacteria and reacts to them and how the
Bacteria protect themselves from those responses.(...)
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Fundação para a Ciência e a Tecnologia
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SFRH
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SFRH/BD/78748/2011