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Journal articleBotella H, Vaubourgeix J, 2019,
Building walls: Work that never ends
, Trends in Microbiology, Vol: 27, Pages: 4-7, ISSN: 0966-842XFluorescent amino acid analogs have proven to be useful tools for studying the dynamics of peptidoglycan metabolism. García-Heredia and colleagues showed that their route of incorporation differs depending on the adjunct fluorophore and applied this property to investigate mycobacterial peptidoglycan synthesis and remodeling with heightened granularity.
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Journal articleJewell P, Dixon L, Singanayagam A, et al., 2019,
Severe disseminated infection with emerging lineage of methicillin-sensitive staphylococcus aureus
, Emerging Infectious Diseases, Vol: 25, Pages: 187-189, ISSN: 1080-6040We report a case of severe disseminated infection in an immunocompetent man caused by an emerging lineage of methicillin-sensitive Staphylococcus aureus clonal complex 398. Genes encoding classic virulence factors were absent. The patient made a slow recovery after multiple surgical interventions and a protracted course of intravenous flucloxacillin.
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Book chapterHaag AF, Ross Fitzgerald J, Penadés JR, 2019,
Staphylococcus aureus in animals
, Gram-Positive Pathogens, Pages: 731-746, ISBN: 9781683670124The genus Staphylococcus currently comprises 81 species and subspecies (https://www.dsmz.de/bacterial-diversity/prokaryotic-nomenclature-up-to-date/prokaryotic-nomenclature-up-to-date.html), and most members of the genus are mammalian commensals or opportunistic pathogens that colonize niches such as skin, nares, and diverse mucosal membranes. Several species are of significant medical or veterinary importance. Staphylococcus pseudintermedius (1) is a leading cause of pyoderma in dogs and is considered to be a significant reservoir of antimicrobial resistance factors for the genus (2, 3). S. pseudintermedius is very similar to Staphylococcus intermedius and can be distinguished from other coagulase-positive staphylococci by positive arginine dihydrolase and acid production from β-gentiobiose and d-mannitol (4) or by using a multiplex-PCR approach targeting the nuclease gene nuc (5). Staphylococcus saprophyticus is the second leading cause of uncomplicated urinary tract infections (6). While Staphylococcus epidermidis is a normal component of the epidermal microbiota, it is a leading cause of biofilm contamination of medical devices (7). The most promiscuous and most significant human pathogenic staphylococcal species is Staphylococcus aureus, which is the causal agent of a variety of disease symptoms that can range from cosmetic to lethal manifestations. S. aureus is distinguished from most members of the genus by its abundant production of secreted coagulase, an enzyme which converts serum fibrinogen to fibrin and promotes clotting. However, the S. intermedius group and some strains of Staphylococcus lugdunensis have coagulase activity (5, 8, 9).
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Journal articleGodlee C, Cerny O, durkin C, et al., 2019,
SrcA is a chaperone for the Salmonella SPI-2 type three secretion system effector SteD
, Microbiology, Vol: 165, Pages: 15-25, ISSN: 1350-0872Effector proteins of type three secretion systems (T3SS) often require cytosolic chaperones for their stabilization, to interact with the secretion machinery and to enable effector delivery into host cells. We found that deletion of srcA, previously shown to encode a chaperone for the Salmonella pathogenicity island 2 (SPI-2) T3SS effectors SseL and PipB2, prevented the reduction of mature Major Histocompatibility Complex class II (mMHCII) from the surface of antigen-presenting cells during Salmonella infection. This activity was shown previously to be caused by the SPI-2 T3SS effector SteD. Since srcA and steD are located in the same operon on the Salmonella chromosome, this suggested that the srcA phenotype might be due to an indirect effect on SteD. We found that SrcA is not translocated by the SPI-2 T3SS but interacts directly and forms a stable complex with SteD in bacteria with a 2 : 1 stoichiometry. We found that SrcA was not required for SPI-2 T3SS-dependent, neutral pH-induced secretion of either SseL or PipB2 but was essential for secretion of SteD. SrcA therefore functions as a chaperone for SteD, explaining its requirement for the reduction in surface levels of mMHCII.
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Journal articleGollan B, Grabe G, Michaux C, et al., 2019,
Bacterial Persisters and Infection: Past, Present, and Progressing
, ANNUAL REVIEW OF MICROBIOLOGY, VOL 73, Vol: 73, Pages: 359-385, ISSN: 0066-4227- Author Web Link
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Journal articleSo EC, Mousnier A, Frankel G, et al., 2019,
Determination of In Vivo Interactomes of Dot/Icm Type IV Secretion System Effectors by Tandem Affinity Purification.
, Methods Mol Biol, Vol: 1921, Pages: 289-303The Dot/Icm type IV secretion system (T4SS) is essential for the pathogenesis of Legionella species and translocates a multitude of effector proteins into host cells. The identification of host cell targets of these effectors is often critical to unravel their roles in controlling the host. Here we describe a method to characterize the protein complexes associated with effectors in infected host cells. To achieve this, Legionella expressing an effector of interest fused to a Bio-tag, a combination of hexahistidine tags and a specific recognition sequence for the biotin ligase BirA, are used to infect host cells expressing BirA, which leads to biotinylation of the translocated effector. Following chemical cross-linking, effector interactomes are isolated by tandem affinity purification employing metal affinity and NeutrAvidin resins and identified by western blotting or mass spectrometry.
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Book chapterCosta TRD, Francis MK, Farag SI, et al., 2019,
Measurement of Yersinia Translocon Pore Formation in Erythrocytes
, Methods in Molecular Biology, Publisher: Springer New York, Pages: 211-229, ISBN: 9781493995400 -
Journal articleFrankel G, Schroeder GN, 2019,
The Galleria mellonella Infection Model for Investigating the Molecular Mechanisms of Legionella Virulence.
, Methods Mol Biol, Vol: 1921, Pages: 333-346Legionella species evolved virulence factors to exploit protozoa as replicative niches in the environment. Cell culture infection models demonstrated that many of these factors also enable the bacteria to thrive in human macrophages; however, these models do not recapitulate the complex interactions between macrophages, lung epithelial, and additional immune cells, which are crucial to control bacterial infections. Thus, suitable infection models are required to understand which bacterial factors are important to trigger disease. Guinea pigs and, most frequently, mice have been successfully used as mammalian model hosts; however, ethical and economic considerations impede their use in high-throughput screening studies of Legionella isolates or small molecule inhibitors.Here, we describe the larvae of the lepidopteran Galleria mellonella as insect model of Legionella pathogenesis. Larvae can be obtained from commercial suppliers in large numbers, maintained without the need of specialized equipment, and infected by injection. Although lacking the complexity of a mammalian immune system, the larvae mount humoral and cellular immune responses to infection. L. pneumophila strain 130b and other prototype isolates withstand these responses and use the Defective in organelle trafficking/Intracellular multiplication (Dot/Icm) type IV secretion system (T4SS ) to inject effectors enabling survival and replication in hemocytes, insect phagocytes, ultimately leading to the death of the larvae. Differences in virulence between L. pneumophila isolates or gene deletion mutants can be analyzed using indicators of larval health and immune induction, such as pigmentation, mobility, histopathology, and survival. Bacterial replication can be measured by plating hemolymph or by immunofluorescence microscopy of isolated circulating hemocytes from infected larvae. Combined, these straightforward experimental readouts make G. mellonella larvae a versatile model host to rapidly assess the v
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Journal articleLarrouy-Maumus GJ, 2019,
Lipids as biomarkers of cancer and bacterial infections
, Current Medicinal Chemistry, Vol: 26, Pages: 1924-1932, ISSN: 0929-8673Lipids are ubiquitous molecules, known to play important roles in various cellular processes. Alterations to the lipidome can therefore be used as a read-out of the signs of disease, highlighting the importance to consider lipids as biomarkers in addition of nucleic acid and proteins. This mini-review exposes the current knowledge and limitations of the use of lipids as biomarkers of the top global killers which are cancer and bacterial infections.
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Journal articleKrokowski S, Lobato-Marquez D, Chastanet A, et al., 2018,
Septins recognize and entrap dividing bacterial cells for delivery to lysosomes
, Cell Host and Microbe, Vol: 24, Pages: 866-874, ISSN: 1931-3128The cytoskeleton occupies a central role in cellular immunity by promoting bacterial sensing and antibacterial functions. Septins are cytoskeletal proteins implicated in various cellular processes, including cell division. Septins also assemble into cage-like structures that entrap cytosolic Shigella, yet how septins recognize bacteria is poorly understood. Here, we discover that septins are recruited to regions of micron-scale membrane curvature upon invasion and division by a variety of bacterial species. Cardiolipin, a curvature-specific phospholipid, promotes septin recruitment to highly curved membranes of Shigella, and bacterial mutants lacking cardiolipin exhibit less septin cage entrapment. Chemically inhibiting cell separation to prolong membrane curvature or reducing Shigella cell growth respectively increases and decreases septin cage formation. Once formed, septin cages inhibit Shigella cell division upon recruitment of autophagic and lysosomal machinery. Thus, recognition of dividing bacterial cells by the septin cytoskeleton is a powerful mechanism to restrict the proliferation of intracellular bacterial pathogens.
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