Abstract
Intracellular replication of Salmonella enterica serovar Typhimurium within membrane-bound compartments, called Salmonella-containing vacuoles, depends on the activities of several effector proteins translocated by the Salmonella pathogenicity island 2 (SPI-2)-encoded type III secretion system. The SPI-2 effector protein SseJ shows similarity at the amino acid level to several GDSL lipases with glycerophospholipid : cholesterol acyltransferase (GCAT) activity. In this study, we show that catalytic serine-dependent phospholipase A (PLA) and GCAT activity of recombinant SseJ is potentiated by factor(s) present in HeLa cells, RAW macrophages and Saccharomyces cerevisiae. SseJ activity was enhanced with increasing amounts of, or preincubation with, eukaryotic cell extracts. Analysis of the activating factor(s) shows that it is soluble and heat- and protease-sensitive. We conclude that PLA and GCAT activities of SseJ are potentiated by proteinaceous eukaryotic factor(s).
Highlights
Numerous Salmonella virulence genes are required for growth of this pathogen in mice; several of these are associated with the Salmonella pathogenicity island 2 (SPI-2) type III secretion system (T3SS)
We show that SseJ exhibits phospholipase A (PLA) and glycerophospholipid : cholesterol acyltransferase (GCAT) activity and that both enzymic activities require the presence of a eukaryotic activator
No enzymic activity was detected at pH 7.4 when GST–SseJ was incubated with paranitrophenyl butyrate (PNPB) (Fig. 1b) or DPPC liposomes (Fig. 1c)
Summary
Numerous Salmonella virulence genes are required for growth of this pathogen in mice; several of these are associated with the Salmonella pathogenicity island 2 (SPI-2) type III secretion system (T3SS). This is expressed upon bacterial entry into host cells and translocates a variety of effector proteins across the SCV into the host cell (Cirillo et al, 1998; Waterman & Holden, 2003). 20 SPI-2 effectors have been identified to date, but their molecular functions remain largely unknown (Haraga et al, 2008; Waterman & Holden, 2003)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
