The oxygenating constituent of 3,6-diketocamphane monooxygenase from the CAM plasmid of Pseudomonas putida: the first crystal structure of a type II Baeyer-Villiger monooxygenase. Corrigendum.

A statement is amended in the article by Isupov et al. [(2015). Acta Cryst.

The oxygenating constituent of 3,6-diketocamphane monooxygenase from the CAM plasmid of Pseudomonas putida: the first crystal structure of a type II Baeyer-Villiger monooxygenase.

The three-dimensional structures of the native enzyme and the FMN complex of the overexpressed form of the oxygenating component of the type II Baeyer-Villiger 3,6-diketocamphane monooxygenase have been determined to 1.9 Å resolution. The structure of this dimeric FMN-dependent enzyme, which is encoded on the large CAM plasmid of Pseudomonas putida, has been solved by a combination of multiple anomalous dispersion from a bromine crystal soak and molecular replacement using a bacterial luciferase model.

The bacterial cytoskeleton modulates motility, type 3 secretion, and colonization in Salmonella.

Although there have been great advances in our understanding of the bacterial cytoskeleton, major gaps remain in our knowledge of its importance to virulence. In this study we have explored the contribution of the bacterial cytoskeleton to the ability of Salmonella to express and assemble virulence factors and cause disease. The bacterial actin-like protein MreB polymerises into helical filaments and interacts with other cytoskeletal elements including MreC to control cell-shape.

WAVE regulatory complex activation by cooperating GTPases Arf and Rac1.

The WAVE regulatory complex (WRC) is a critical element in the control of actin polymerization at the eukaryotic cell membrane, but how WRC is activated remains uncertain. While Rho GTPase Rac1 can bind and activate WRC in vitro, this interaction is of low affinity, suggesting other factors may be important. By reconstituting WAVE-dependent actin assembly on membrane-coated beads in mammalian cell extracts, we found that Rac1 was not sufficient to engender bead motility, and we uncovered a key requirement for Arf GTPases.

Salmonella takes control: effector-driven manipulation of the host.

Salmonella pathogenesis relies upon the delivery of over thirty specialised effector proteins into the host cell via two distinct type III secretion systems. These effectors act in concert to subvert the host cell cytoskeleton, signal transduction pathways, membrane trafficking and pro-inflammatory responses. This allows Salmonella to invade non-phagocytic epithelial cells, establish and maintain an intracellular replicative niche and, in some cases, disseminate to cause systemic disease.

Repetitive N-WASP-binding elements of the enterohemorrhagic Escherichia coli effector EspF(U) synergistically activate actin assembly.

Enterohemorrhagic Escherichia coli (EHEC) generate F-actin-rich adhesion pedestals by delivering effector proteins into mammalian cells. These effectors include the translocated receptor Tir, along with EspF(U), a protein that associates indirectly with Tir and contains multiple peptide repeats that stimulate actin polymerization. In vitro, the EspF(U) repeat region is capable of binding and activating recombinant derivatives of N-WASP, a host actin nucleation-promoting factor.

Cholesterol binding by the bacterial type III translocon is essential for virulence effector delivery into mammalian cells.

A ubiquitous early step in infection of man and animals by enteric bacterial pathogens like Salmonella, Shigella and enteropathogenic Escherichia coli (EPEC) is the translocation of virulence effector proteins into mammalian cells via specialized type III secretion systems (TTSSs). Translocated effectors subvert the host cytoskeleton and stimulate signalling to promote bacterial internalization or survival. Target cell plasma membrane cholesterol is central to pathogen-host cross-talk, but the precise nature of its critical contribution remains unknown.

Control of actin turnover by a salmonella invasion protein.

Salmonella force their way into nonphagocytic host intestinal cells to initiate infection. Uptake is triggered by delivery into the target cell of bacterial effector proteins that stimulate cytoskeletal rearrangements and membrane ruffling. The Salmonella invasion protein A (SipA) effector is an actin binding protein that enhances uptake efficiency by promoting actin polymerization.

The purified Shigella IpaB and Salmonella SipB translocators share biochemical properties and membrane topology.

An essential early event in Shigella and Salmonella pathogenesis is invasion of non-phagocytic intestinal epithelial cells. Pathogen entry is triggered by the delivery of multiple bacterial effector proteins into target mammalian cells. The Shigella invasion plasmid antigen B (IpaB), which inserts into the host plasma membrane, is required for effector delivery and invasion.

A Salmonella SipB-derived polypeptide blocks the 'trigger' mechanism of bacterial entry into eukaryotic cells.

Entry into non-phagocytic mammalian cells by the invasive pathogens Salmonella and Shigella is triggered by the delivery of bacterial virulence effector proteins into the host cell. This is dependent upon Salmonella SipB or its Shigella homologue IpaB, which insert into the eukaryotic cell plasma membrane. Here we show that a SipB-derived 166 residue alpha-helical polypeptide is a potent inhibitor of SipB-directed liposome fusion in vitro, preventing the membrane-associated form of SipB from inserting deeply into the bilayer.

Topology of the Salmonella invasion protein SipB in a model bilayer.

A critical early event in Salmonella infection is entry into intestinal epithelial cells. The Salmonella invasion protein SipB is required for the delivery of bacterial effector proteins into target eukaryotic cells, which subvert signal transduction pathways and cytoskeletal dynamics. SipB inserts into the host plasma membrane during infection, and the purified protein has membrane affinity and heterotypic membrane fusion activity in vitro.