| essentiality of threonylcarbamoyladenosine (t(6)a), a universal trna modification, in bacteria. | threonylcarbamoyladenosine (t(6)a) is a modified nucleoside universally conserved in trnas in all three kingdoms of life. the recently discovered genes for t(6)a synthesis, including tsac and tsad, are essential in model prokaryotes but not essential in yeast. these genes had been identified as antibacterial targets even before their functions were known. however, the molecular basis for this prokaryotic-specific essentiality has remained a mystery. here, we show that t(6)a is a strong positive ... | 2015 | 26337258 |
| guanylate binding proteins enable rapid activation of canonical and noncanonical inflammasomes in chlamydia-infected macrophages. | interferon (ifn)-inducible guanylate binding proteins (gbps) mediate cell-autonomous host resistance to bacterial pathogens and promote inflammasome activation. the prevailing model postulates that these two gbp-controlled activities are directly linked through gbp-dependent vacuolar lysis. it was proposed that the rupture of pathogen-containing vacuoles (pvs) by gbps destroyed the microbial refuge and simultaneously contaminated the host cell cytosol with microbial activators of inflammasomes. ... | 2015 | 26416908 |
| short, synthetic cationic peptides have antibacterial activity against mycobacterium smegmatis by forming pores in membrane and synergizing with antibiotics. | multicellular organisms are constantly exposed to a multitude of pathogenic microbes. infection is inhibited in vivo by the innate and adaptive immune system. mycobacterium species have emerged that are resistant to most antibiotics. we identified several naturally occurring cationic antimicrobial peptides that were active at low micromolar concentrations against mycobacterium smegmatis. human-derived cathelicidin ll-37 is well characterized and studied against m. smegmatis; we compared ll-37 wi ... | 2015 | 27025629 |
| novel perspectives on non-canonical inflammasome activation. | inflammasomes are cytosolic multi-protein complexes that regulate the secretion of the proinflammatory cytokines, il-1β and il-18, and induce pyroptosis, an inflammatory form of cell death. the nlrp3 inflammasome is the most well-characterized member of this family and functions by sensing intracellular pathogen- and damage-associated molecular patterns and activating caspase-1, which processes the biologically inactive il-1β and il-18 precursors into active cytokines. recent studies have identi ... | 2015 | 27471719 |
| snake cathelicidin na-cath and smaller helical antimicrobial peptides are effective against burkholderia thailandensis. | burkholderia thailandensis is a gram-negative soil bacterium used as a model organism for b. pseudomallei, the causative agent of melioidosis and an organism classified category b priority pathogen and a tier 1 select agent for its potential use as a biological weapon. burkholderia species are reportedly "highly resistant" to antimicrobial agents, including cyclic peptide antibiotics, due to multiple resistance systems, a hypothesis we decided to test using antimicrobial (host defense) peptides. ... | 2015 | 26196513 |
| enterococcus faecalis glycolipids modulate lipoprotein-content of the bacterial cell membrane and host immune response. | in this study, we investigated the impact of the cell membrane composition of e. faecalis on its recognition by the host immune system. to this end, we employed an e. faecalis deletion mutant (δbgsa) that does not synthesize the major cell membrane glycolipid diglycosyl-diacylglycerol (dglcdag). proteomic analysis revealed that 13 of a total of 21 upregulated surface-associated proteins of e. faecalis δbgsa were lipoproteins. this led to a total lipoprotein content in the cell membrane of 35.8% ... | 2015 | 26172831 |
| epigenetic modulation of microglial inflammatory gene loci in helminth-induced immune suppression: implications for immune regulation in neurocysticercosis. | in neurocysticercosis, parasite-induced immune suppressive effects are thought to play an important role in enabling site-specific inhibition of inflammatory responses to infections. it is axiomatic that microglia-mediated (m1 proinflammatory) response causes central nervous system inflammation; however, the mechanisms by which helminth parasites modulate microglia activation remain poorly understood. here, we show that microglia display a diminished expression of m1-inflammatory mediators such ... | 2015 | 26148848 |
| inflammasomes: mechanism of action, role in disease, and therapeutics. | the inflammasomes are innate immune system receptors and sensors that regulate the activation of caspase-1 and induce inflammation in response to infectious microbes and molecules derived from host proteins. they have been implicated in a host of inflammatory disorders. recent developments have greatly enhanced our understanding of the molecular mechanisms by which different inflammasomes are activated. additionally, increasing evidence in mouse models, supported by human data, strongly implicat ... | 2015 | 26121197 |
| a tug-of-war between the host and the pathogen generates strategic hotspots for the development of novel therapeutic interventions against infectious diseases. | microbial pathogens are known to express an array of specific signaling molecules referred as pathogen associated molecular patterns (pamps), which are recognized by pattern recognition receptors (prrs), present on the surface of the host cells. interactions between pamps and prrs on the surface of the host cells lead to signaling events which could culminate into either successful infection or clearance of the pathogens. here, we summarize how these events may generate novel host based as well ... | 2015 | 26107578 |
| structure principles of crispr-cas surveillance and effector complexes. | the pathway of crispr-cas immunity redefines the roles of rna in the flow of genetic information and ignites excitement for next-generation gene therapy tools. crispr-cas machineries offer a fascinating set of new enzyme assemblies from which one can learn principles of molecular interactions and chemical activities. the interference step of the crispr-cas immunity pathway congregates proteins, rna, and dna into a single molecular entity that selectively destroys invading nucleic acids. although ... | 2015 | 26048003 |
| human caspase-4 mediates noncanonical inflammasome activation against gram-negative bacterial pathogens. | inflammasomes are critical for host defense against bacterial pathogens. in murine macrophages infected by gram-negative bacteria, the canonical inflammasome activates caspase-1 to mediate pyroptotic cell death and release of il-1 family cytokines. additionally, a noncanonical inflammasome controlled by caspase-11 induces cell death and il-1 release. however, humans do not encode caspase-11. instead, humans encode two putative orthologs: caspase-4 and caspase-5. whether either ortholog functions ... | 2015 | 25964352 |
| pyroptotic cell death defends against intracellular pathogens. | inflammatory caspases play a central role in innate immunity by responding to cytosolic signals and initiating a twofold response. first, caspase-1 induces the activation and secretion of the two prominent pro-inflammatory cytokines, interleukin-1β (il-1β) and il-18. second, either caspase-1 or caspase-11 can trigger a form of lytic, programmed cell death called pyroptosis. pyroptosis operates to remove the replication niche of intracellular pathogens, making them susceptible to phagocytosis and ... | 2015 | 25879289 |
| cas9-mediated targeting of viral rna in eukaryotic cells. | clustered, regularly interspaced, short palindromic repeats-crispr associated (crispr-cas) systems are prokaryotic rna-directed endonuclease machineries that act as an adaptive immune system against foreign genetic elements. using small crispr rnas that provide specificity, cas proteins recognize and degrade nucleic acids. our previous work demonstrated that the cas9 endonuclease from francisella novicida (fncas9) is capable of targeting endogenous bacterial rna. here, we show that fncas9 can be ... | 2015 | 25918406 |
| applications of cas9 as an rna-programmed rna-binding protein. | the streptococcus pyogenes crispr-cas system has gained widespread application as a genome editing and gene regulation tool as simultaneous cellular delivery of the cas9 protein and guide rnas enables recognition of specific dna sequences. the recent discovery that cas9 can also bind and cleave rna in an rna-programmable manner indicates the potential utility of this system as a universal nucleic acid-recognition technology. rna-targeted cas9 (rcas9) could allow identification and manipulation o ... | 2015 | 25880497 |
| bacterial recognition pathways that lead to inflammasome activation. | inflammasomes are multi-protein signaling platforms that upon activation trigger the maturation of the pro-inflammatory cytokines, interleukin-1β (il-1β) and il-18, and cell death. inflammasome sensors detect microbial and host-derived molecules. here, we review the mechanisms of inflammasome activation triggered by bacterial infection, primarily focusing on two model intracellular bacterial pathogens, francisella novicida and salmonella typhimurium. we discuss the complex relationship between b ... | 2015 | 25879288 |
| massively parallel delivery of large cargo into mammalian cells with light pulses. | we report a high-throughput platform for delivering large cargo elements into 100,000 cells in 1 min. our biophotonic laser-assisted surgery tool (blast) generates an array of microcavitation bubbles that explode in response to laser pulsing, forming pores in adjacent cell membranes through which cargo is gently driven by pressurized flow. the platform delivers large items including bacteria, enzymes, antibodies and nanoparticles into diverse cell types with high efficiency and cell viability. w ... | 2015 | 25849636 |
| helicobacter pylori outer membrane protein 18 (hp1125) is involved in persistent colonization by evading interferon- γ signaling. | outer membrane proteins (omps) can induce an immune response. omp18 (hp1125) of h. pylori is a powerful antigen that can induce significant interferon-γ (ifn-γ) levels. previous studies have suggested that ifn-γ plays an important role in h. pylori clearance. however, h. pylori has multiple mechanisms to avoid host immune surveillance for persistent colonization. we generated an omp18 mutant (h. pylori 26695 and h. pylori ss1) strain to examine whether omp18 interacts with ifn-γ and is involved ... | 2015 | 25945338 |
| atomic structures of a bactericidal contractile nanotube in its pre- and postcontraction states. | r-type pyocins are representatives of contractile ejection systems, a class of biological nanomachines that includes, among others, the bacterial type vi secretion system (t6ss) and contractile bacteriophage tails. we report atomic models of the pseudomonas aeruginosa precontraction pyocin sheath and tube, and the postcontraction sheath, obtained by cryo-em at 3.5-å and 3.9-å resolutions, respectively. the central channel of the tube is negatively charged, in contrast to the neutral and positive ... | 2015 | 25822993 |
| innate immune recognition of dna: a recent history. | innate immune dna sensing underpins many physiological and pathological responses to dna, including anti-viral immunity to dna viruses. although it has been appreciated for many years that cytosolic dna can evoke a type i interferon response, it is only within the past decade that the cellular mechanisms responsible for such a response have been defined. here we review the discoveries that led to an appreciation of the existence of cytosolic dna sensor proteins, and discuss two key such sensors, ... | 2015 | 25816762 |
| crispr-cas9: how research on a bacterial rna-guided mechanism opened new perspectives in biotechnology and biomedicine. | | 2015 | 25796552 |
| cpf1 is a versatile tool for crispr genome editing across diverse species of cyanobacteria. | cyanobacteria are the ideal organisms for the production of a wide range of bioproducts as they can convert co2 directly into the desired end product using solar energy. unfortunately, the engineering of cyanobacteria to create efficient cell factories has been impaired by the cumbersome genetic tools that are currently available for these organisms; especially when trying to accumulate multiple modifications. we sought to construct an efficient and precise tool for generating numerous markerles ... | 2016 | 28000776 |
| the power of crispr-cas9-induced genome editing to speed up plant breeding. | genome editing with engineered nucleases enabling site-directed sequence modifications bears a great potential for advanced plant breeding and crop protection. remarkably, the rna-guided endonuclease technology (rgen) based on the clustered regularly interspaced short palindromic repeats (crispr) and crispr-associated protein 9 (cas9) is an extremely powerful and easy tool that revolutionizes both basic research and plant breeding. here, we review the major technical advances and recent applicat ... | 2016 | 28097123 |
| gene editing approaches against viral infections and strategy to prevent occurrence of viral escape. | | 2016 | 27930735 |
| efficient targeted mutagenesis of rice and tobacco genomes using cpf1 from francisella novicida. | crispr/cas9 systems are nowadays applied extensively to effect genome editing in various organisms including plants. crispr from prevotella and francisella 1 (cpf1) is a newly characterized rna-guided endonuclease that has two distinct features as compared to cas9. first, cpf1 utilizes a thymidine-rich protospacer adjacent motif (pam) while cas9 prefers a guanidine-rich pam. cpf1 could be used as a sequence-specific nuclease to target at-rich regions of a genome that cas9 had difficulty accessin ... | 2016 | 27905529 |
| patterns of crispr/cas9 activity in plants, animals and microbes. | the crispr/cas9 system and related rna-guided endonucleases can introduce double-strand breaks (dsbs) at specific sites in the genome, allowing the generation of targeted mutations in one or more genes as well as more complex genomic rearrangements. modifications of the canonical crispr/cas9 system from streptococcus pyogenes and the introduction of related systems from other bacteria have increased the diversity of genomic sites that can be targeted, providing greater control over the resolutio ... | 2016 | 27614091 |
| cpf1 nucleases demonstrate robust activity to induce dna modification by exploiting homology directed repair pathways in mammalian cells. | cpf1 nucleases have recently been repurposed for site-specific genome modification. two members of the cpf1 family, the ascpf1 from acidaminococcus sp. and the lbcpf1 from lachnospiraceae bacterium were shown to induce higher indel frequencies than spcas9 when examining four randomly-selected target sequences for each type of nuclease. whether they are a real match for cas9 nucleases, however, remains to be verified. | 2016 | 27630115 |
| proteomic discovery of host kinase signaling in bacterial infections. | protein phosphorylation catalyzed by protein kinases acts as a reversible molecular switch in signal transduction, providing a mechanism for the control of protein function in cellular processes. during microbial infection, cellular signaling essentially contributes to immune control to restrict the dissemination of invading pathogens within the host organism. however, pathogenic microbes compete for the control of host signaling to create a beneficial environment for successful invasion and inf ... | 2016 | 27440122 |
| ge-crispr - an integrated pipeline for the prediction and analysis of sgrnas genome editing efficiency for crispr/cas system. | genome editing by sgrna a component of crispr/cas system emerged as a preferred technology for genome editing in recent years. however, activity and stability of sgrna in genome targeting is greatly influenced by its sequence features. in this endeavor, a few prediction tools have been developed to design effective sgrnas but these methods have their own limitations. therefore, we have developed "ge-crispr" using high throughput data for the prediction and analysis of sgrnas genome editing effic ... | 2016 | 27581337 |
| imipenem represses crispr-cas interference of dna acquisition through h-ns stimulation in klebsiella pneumoniae. | analysis of the genome of klebsiella pneumoniae ntuh-k2044 strain revealed the presence of two clustered regularly interspaced short palindromic repeats (crispr) arrays separated with crispr-associated (cas) genes. carbapenem-resistant k. pneumoniae isolates were observed to be less likely to have crispr-cas than sensitive strains (5/85 vs. 22/132). removal of the transcriptional repressor, h-ns, was shown to prevent the transformation of plasmids carrying a spacer and putative proto-spacer adja ... | 2016 | 27531594 |
| zbp1/dai is an innate sensor of influenza virus triggering the nlrp3 inflammasome and programmed cell death pathways. | the interferon-inducible protein z-dna binding protein 1 (zbp1, also known as dna-dependent activator of ifn-regulatory factors (dai) and dlm-1) was identified as a dsdna sensor, which instigates innate immune responses. however, this classification has been disputed and whether zbp1 functions as a pathogen sensor during an infection has remained unknown. herein, we demonstrated zbp1-mediated sensing of the influenza a virus (iav) proteins np and pb1, triggering cell death and inflammatory respo ... | 2016 | 27917412 |
| crispr system acquisition and evolution of an obligate intracellular chlamydia-related bacterium. | recently, a new chlamydia-related organism, protochlamydia naegleriophila knic, was discovered within a naegleria amoeba. to decipher the mechanisms at play in the modeling of genomes from the protochlamydia genus, we sequenced the full genome of pr. naegleriophila, which includes a 2,885,090 bp chromosome and a 145,285 bp megaplasmid. for the first time within the chlamydiales order, we describe the presence of a clustered regularly interspaced short palindromic repeats (crispr) system, the imm ... | 2016 | 27516530 |
| functional definition of bira suggests a biotin utilization pathway in the zoonotic pathogen streptococcus suis. | biotin protein ligase is universal in three domains of life. the paradigm version of bpl is the escherichia coli bira that is also a repressor for the biotin biosynthesis pathway. streptococcus suis, a leading bacterial agent for swine diseases, seems to be an increasingly-important opportunistic human pathogen. unlike the scenario in e. coli, s. suis lacks the de novo biotin biosynthesis pathway. in contrast, it retains a bioy, a biotin transporter-encoding gene, indicating an alternative survi ... | 2016 | 27217336 |
| recent advances in genome editing using crispr/cas9. | the crispr (clustered regularly interspaced short palindromic repeat)-cas9 (crispr-associated nuclease 9) system is a versatile tool for genome engineering that uses a guide rna (grna) to target cas9 to a specific sequence. this simple rna-guided genome-editing technology has become a revolutionary tool in biology and has many innovative applications in different fields. in this review, we briefly introduce the cas9-mediated genome-editing method, summarize the recent advances in crispr/cas9 tec ... | 2016 | 27252719 |
| superinfection exclusion of the ruminant pathogen anaplasma marginale in its tick vector is dependent on the time between exposures to the strains. | the remarkable genetic diversity of vector-borne pathogens allows for the establishment of superinfection in the mammalian host. to have a long-term impact on population strain structure, the introduced strains must also be transmitted by a vector population that has been exposed to the existing primary strain. the sequential exposure of the vector to multiple strains frequently prevents establishment of the second strain, a phenomenon termed superinfection exclusion. as a consequence, superinfe ... | 2016 | 26994084 |
| crystal structure of cpf1 in complex with guide rna and target dna. | cpf1 is an rna-guided endonuclease of a type v crispr-cas system that has been recently harnessed for genome editing. here, we report the crystal structure of acidaminococcus sp. cpf1 (ascpf1) in complex with the guide rna and its target dna at 2.8 å resolution. ascpf1 adopts a bilobed architecture, with the rna-dna heteroduplex bound inside the central channel. the structural comparison of ascpf1 with cas9, a type ii crispr-cas nuclease, reveals both striking similarity and major differences, t ... | 2016 | 27114038 |
| interferon-induced guanylate-binding proteins in inflammasome activation and host defense. | traditional views of the inflammasome highlight the assembly of pre-existing core components shortly after infection or tissue damage. emerging work, however, suggests that the inflammasome machinery is also subject to 'tunable' or inducible signals that might accelerate its autocatalytic properties and dictate where inflammasome assembly takes place in the cell. many of these signals operate downstream of interferon receptors to elicit inflammasome regulators, including a new family of interfer ... | 2016 | 27092805 |
| human gbp1 does not localize to pathogen vacuoles but restricts toxoplasma gondii. | guanylate binding proteins (gbps) are a family of large interferon-inducible gtpases that are transcriptionally upregulated upon infection with intracellular pathogens. murine gbps (mgbps) including mgbp1 and 2 localize to and disrupt pathogen-containing vacuoles (pvs) resulting in the cell-autonomous clearing or innate immune detection of pv-resident pathogens. human gbps (hgbps) are known to exert antiviral host defense and activate the nlrp3 inflammasome, but it is unclear whether hgbps can d ... | 2016 | 26874079 |
| the role of airway macrophages in apoptotic cell clearance following acute and chronic lung inflammation. | acute and chronic inflammatory responses in the lung are associated with the accumulation of large quantities of immune and structural cells undergoing apoptosis, which need to be engulfed by phagocytes in a process called 'efferocytosis'. apoptotic cell recognition and removal from the lung is mediated predominantly by airway macrophages, though immature dendritic cells and non-professional phagocytes, such as epithelial cells and mesenchymal cells, can also display this function. efficient cle ... | 2016 | 26957481 |
| salmonella suppresses the trif-dependent type i interferon response in macrophages. | salmonella enterica is an intracellular pathogen that causes diseases ranging from gastroenteritis to typhoid fever. salmonella bacteria trigger an autophagic response in host cells upon infection but have evolved mechanisms for suppressing this response, thereby enhancing intracellular survival. we recently reported that s. enterica serovar typhimurium actively recruits the host tyrosine kinase focal adhesion kinase (fak) to the surface of the salmonella-containing vacuole (scv) (k. a. owen et ... | 2016 | 26884434 |
| structure and engineering of francisella novicida cas9. | the rna-guided endonuclease cas9 cleaves double-stranded dna targets complementary to the guide rna and has been applied to programmable genome editing. cas9-mediated cleavage requires a protospacer adjacent motif (pam) juxtaposed with the dna target sequence, thus constricting the range of targetable sites. here, we report the 1.7 å resolution crystal structures of cas9 from francisella novicida (fncas9), one of the largest cas9 orthologs, in complex with a guide rna and its pam-containing dna ... | 2016 | 26875867 |
| quantitative proteomic analysis of shigella flexneri and shigella sonnei generalized modules for membrane antigens (gmma) reveals highly pure preparations. | outer membrane blebs are naturally shed by gram-negative bacteria and are candidates of interest for vaccines development. genetic modification of bacteria to induce hyperblebbing greatly increases the yield of blebs, called generalized modules for membrane antigens (gmma). the composition of the gmma from hyperblebbing mutants of shigella flexneri 2a and shigella sonnei were quantitatively analyzed using high-sensitivity mass spectrometry with the label-free ibaq procedure and compared to the c ... | 2016 | 26746581 |
| modification of the 1-phosphate group during biosynthesis of capnocytophaga canimorsus lipid a. | capnocytophaga canimorsus, a commensal bacterium of dog's mouth flora causing severe infections in humans after dog bites or scratches, has a lipopolysaccharide (lps) (endotoxin) with low-inflammatory lipid a. in particular, it contains a phosphoethanolamine (p-etn) instead of a free phosphate group at the c-1 position of the lipid a backbone, usually present in highly toxic enterobacterial gram-negative lipid a. here we show that the c. canimorsus genome comprises a single operon encoding a lip ... | 2016 | 26644381 |
| a crispr/cas9 and cre/lox system-based express vaccine development strategy against re-emerging pseudorabies virus. | virus evolves rapidly to escape vaccine-induced immunity, posing a desperate demand for efficient vaccine development biotechnologies. here we present an express vaccine development strategy based on crispr/cas9 and cre/lox system against re-emerging pseudorabies virus, which caused the recent devastating swine pseudorabies outbreak in china. by crispr/cas9 system, the virulent genes of the newly isolated strain were simultaneously substituted by marker genes, which were subsequently excised usi ... | 2016 | 26777545 |
| enhanced survival but not amplification of francisella spp. in the presence of free-living amoebae. | transmission of francisella tularensis, the etiologic agent of tularemia, has been associated with various water sources. survival of many waterborne pathogens within free-living amoeba (fla) is well documented; however, the role of amoebae in the environmental persistence of f. tularensis is unclear. in this study, axenic fla cultures of acanthamoeba castellanii, acanthamoeba polyphaga, and vermamoeba vermiformis were each inoculated with virulent strains of f. tularensis (types a and b), the a ... | 2017 | 27929353 |
| the bacterial microbiome of dermacentor andersoni ticks influences pathogen susceptibility. | ticks are of medical importance owing to their ability to transmit pathogens to humans and animals. the rocky mountain wood tick, dermacentor andersoni, is a vector of a number of pathogens, including anaplasma marginale, which is the most widespread tick-borne pathogen of livestock. although ticks host pathogenic bacteria, they also harbor bacterial endosymbionts that have a role in tick physiology, survival, as well as pathogen acquisition and transmission. the goal of this study was to charac ... | 2016 | 26882265 |
| differential roles of caspase-1 and caspase-11 in infection and inflammation. | caspase-1, also known as interleukin-1β (il-1β)-converting enzyme (ice), regulates antimicrobial host defense, tissue repair, tumorigenesis, metabolism and membrane biogenesis. on activation within an inflammasome complex, caspase-1 induces pyroptosis and converts pro-il-1β and pro-il-18 into their biologically active forms. "ice(-/-)" or "casp1(-/-)" mice generated using 129 embryonic stem cells carry a 129-associated inactivating passenger mutation on the caspase-11 locus, essentially making t ... | 2017 | 28345580 |
| acyl carrier protein is a bacterial cytoplasmic target of cationic antimicrobial peptide ll-37. | in addition to membrane disruption, the cathelicidin antimicrobial peptide (amp) ll-37 translocates through the bacterial inner membrane to target intracellular molecules. the present study aims to identify an alternate mechanism and a cytoplasmic target of ll-37 in francisella. ll-37 binding proteins from francisella novicida u112 bacterial lysates were precipitated by using biotinylated ll-37 (b-ll-37) and neutravidin-agarose beads. bound proteins were identified by lc-ms/ms, validated and cha ... | 2015 | 26188040 |
| interferon-inducible guanylate-binding proteins at the interface of cell-autonomous immunity and inflammasome activation. | guanylate-binding proteins (gbps) are essential components of cell-autonomous immunity. in response to ifn signaling, gbps are expressed in the cytoplasm of immune and nonimmune cells, where they unleash their antimicrobial activity toward intracellular bacteria, viruses, and parasites. recent studies have revealed that gbps are essential for mediating activation of the caspase-1 inflammasome in response to the gram-negative bacteria salmonella enterica serovar typhimurium, francisella novicida, ... | 2017 | 27418355 |
| crystal structure and activity of francisella novicida udp-n-acetylglucosamine acyltransferase. | the first step of lipid a biosynthesis in escherichia coli (e. coli) is catalyzed by lpxa (eclpxa), an acyltransferase selective for udp-n-acetylglucosamine (udp-glcnac) and r-3-hydroxymyristoyl-acyl carrier protein (3-oh-c14-acp), and is an essential step in majority of gram-negative bacteria. since the majority of lipid a species isolated from f. novicida contains 3-oh-c16 or 3-oh-c18 at its c3 and c3' positions, fnlpxa was thought to be selective for longer acyl chain (3-oh-c16 and 3-oh-c18) ... | 2016 | 27545601 |
| identifying and visualizing functional pam diversity across crispr-cas systems. | crispr-cas adaptive immune systems in prokaryotes boast a diversity of protein families and mechanisms of action, where most systems rely on protospacer-adjacent motifs (pams) for dna target recognition. here, we developed an in vivo, positive, and tunable screen termed pam-scanr (pam screen achieved by not-gate repression) to elucidate functional pams as well as an interactive visualization scheme termed the pam wheel to convey individual pam sequences and their activities. pam-scanr and the pa ... | 2016 | 27041224 |
| identification and characterization of episomal forms of integrative genomic islands in the genus francisella. | recently, we identified a putative prophage on a genomic island (gi) within the genome sequence of francisella hispaniensis isolate as0-814 (francisella tularensis subsp. novicida-like 3523) by the analysis of the crispr-cas systems of francisella. various spacer dnas within the crispr region of different f. tularensis subsp. novicida strains were found to be homologous to the putative prophage (schunder et al., 2013, int. j. med. microbiol. 303:51-60). now we identified the gi (fhagi-1) as a mo ... | 2015 | 26358917 |
| whole-genome relationships among francisella bacteria of diverse origins define new species and provide specific regions for detection. | francisella tularensis is a highly virulent zoonotic pathogen that causes tularemia and, because of weaponization efforts in past world wars, is considered a tier 1 biothreat agent. detection and surveillance of f. tularensis may be confounded by the presence of uncharacterized, closely related organisms. through dna-based diagnostics and environmental surveys, novel clinical and environmental francisella isolates have been obtained in recent years. here we present 7 new francisella genomes and ... | 2017 | 27881415 |
| evolution toward high-level fluoroquinolone resistance in francisella species. | francisella tularensis, a cdc class a potential bioterrorism agent, is a gram-negative bacterium responsible for tularaemia. understanding the mechanisms of resistance to antibiotics used as first-line treatment is of major security relevance. | 2014 | 23963236 |
| potentiation of the fosmidomycin analogue fr 900098 with substituted 2-oxazolines against francisella novicida. | a library of 33 compounds was screened for potentiation of the antibiotic fr 900098 against the francisella tularensis surrogate francisella novicida. from the screen a highly potent 2-oxazoline adjuvant was discovered capable of potentiating fr 900098 with a 1000-fold reduction in mic against the francisella sub-species f. novicida and f. philomiragia. | 2016 | 28154750 |
| murine survival of infection with francisella novicida and protection against secondary challenge is critically dependent on b lymphocytes. | respiratory infection of mice with francisella novicida has recently been used as a model for the highly virulent human pathogen francisella tularensis. similar to f. tularensis, even small doses of f. novicida administered by respiratory routes are lethal for inbred laboratory mice. this feature obviously limits study of infection-induced immunity. parenteral sublethal infections of mice with f. novicida are feasible, but the resulting immune responses are incompletely characterized. here we us ... | 2017 | 27965147 |
| francisella inflammasomes: integrated responses to a cytosolic stealth bacterium. | francisella tularensis is a facultative intracellular bacterium causing tularemia, a zoonotic disease. francisella replicates in the macrophage cytosol and eventually triggers cytosolic immune responses. in murine macrophages, francisella novicida and francisella tularensis live vaccine strain lyse in the host cytosol and activate the cytosolic dna receptor aim2. here, we review the mechanisms leading or contributing to aim2 inflammasome activation, including the role of tlrs and of ifn signalin ... | 2016 | 27460813 |
| reclassification of wolbachia persica as francisella persica comb. nov. and emended description of the family francisellaceae. | the taxonomic status of the bacterium wolbachia persica is described, and based on the evidence presented, transfer of this species to the genus francisella as francisella persica comb. nov. is proposed. this reclassification is supported by data generated from genomic comparisons of w. persica atcc vr-331t ( = fsc845t = dsm 101678t) to other near neighbours, including francisella tularensis subsp. novicida. the full-length 16s rrna gene sequence of strain atcc vr-331t had 98.5 % nucleotide iden ... | 2016 | 26747442 |
| morphological analysis of francisella novicida epithelial cell infections in the absence of functional fipa. | francisella novicida is a surrogate pathogen commonly used to study infections by the potential bioterrorism agent, francisella tularensis. one of the primary sites of francisella infections is the liver where >90% of infected cells are hepatocytes. it is known that once francisella enter cells it occupies a membrane-bound compartment, the francisella-containing vacuole (fcv), from which it rapidly escapes to replicate in the cytosol. recent work examining the francisella disulfide bond formatio ... | 2016 | 26239909 |
| outbreak of francisella novicida bacteremia among inmates at a louisiana correctional facility. | francisella novicida is a rare cause of human illness despite its close genetic relationship to francisella tularensis, the agent of tularemia. during april-july 2011, 3 inmates at a louisiana correctional facility developed f. novicida bacteremia; 1 inmate died acutely. | 2014 | 24944231 |
| asc controls ifn-γ levels in an il-18-dependent manner in caspase-1-deficient mice infected with francisella novicida. | the inflammasome is a signaling platform that is central to the innate immune responses to bacterial infections. francisella tularensis is a bacterium replicating within the host cytosol. during f. tularensis subspecies novicida infection, aim2, an inflammasome receptor sensing cytosolic dna, activates caspase-1 in an asc-dependent manner, leading to both pyroptosis and release of the proinflammatory cytokines il-1β and il-18. activation of this canonical inflammasome pathway is key to limit f. ... | 2013 | 23975862 |
| generation of protection against francisella novicida in mice depends on the pathogenicity protein pdpa, but not pdpc or pdpd. | previous results suggest that mutations in most genes in the francisella pathogenicity island (fpi) attenuate the bacterium. using a mouse model, here we determined the impact of mutations in pdpa, pdpc, and pdpd in francisella novicida on in vitro replication in macrophages, and in vivo immunogenicity. in contrast to most fpi genes, deletion of pdpc (fnδpdpc) and pdpd (fnδpdpd) from f. novicida did not impact growth in mouse bone-marrow derived macrophages. nonetheless, both fnδpdpc and fnδpdpd ... | 2013 | 23880085 |
| francisella is sensitive to insect antimicrobial peptides. | francisella tularensis causes the zoonotic disease tularemia. arthropod vectors are important transmission routes for the disease, although it is not known how francisella survives the efficient arthropod immune response. here, we used drosophila melanogaster as a model host for francisella infections and investigated whether the bacteria are resistant to insect humoral immune responses, in particular to the antimicrobial peptides (amps) secreted into the insect hemolymph. moreover, we asked to ... | 2013 | 23037919 |
| advances with using crispr/cas-mediated gene editing to treat infections with hepatitis b virus and hepatitis c virus. | chronic infections with hepatitis b and hepatitis c viruses (hbv and hcv) account for the majority of cases of cirrhosis and hepatocellular carcinoma. current therapies for the infections have limitations and improved efficacy is necessary to prevent complications in carriers of the viruses. in the case of hbv persistence, the replication intermediate comprising covalently closed circular dna (cccdna) is particularly problematic. licensed therapies have little effect on cccdna and hbv replicatio ... | 2017 | 28087399 |
| quantification of cytosolic vs. vacuolar salmonella in primary macrophages by differential permeabilization. | intracellular bacterial pathogens can replicate in the cytosol or in specialized pathogen-containing vacuoles (pcvs). to reach the cytosol, bacteria like shigella flexneri and francisella novicida need to induce the rupture of the phagosome. in contrast, salmonella typhimurium replicates in a vacuolar compartment, known as salmonella-containing vacuole (scv). however certain mutants of salmonella fail to maintain scv integrity and are thus released into the cytosol. the percentage of cytosolic v ... | 2015 | 26274778 |
| use of essential gene, encoding prophobilinogen deaminase from extreme psychrophilic colwellia sp. c1, to generate temperature-sensitive strain of francisella novicida. | previously, several essential genes from psychrophilic bacteria have been substituted for their homologues in mesophilic bacterial pathogens to make the latter temperature sensitive. it has been noted that an essential liga gene from an extreme psychrophile, colwellia sp. c1, yielded a gene product that is inactivated at 27°c, the lowest that has been observed for any psychrophilic enzyme, and hypothesized that other essential proteins of that strain would also have low inactivation temperatures ... | 2016 | 27248501 |
| mass spectrometry analysis of intact francisella bacteria identifies lipid a structure remodeling in response to acidic ph stress. | structural modification of lipid a, the lipid anchor of lps, is one of the strategies used by gram-negative bacteria to evade host innate immunity. francisella tularensis is a human pathogen that infects and replicates within phagocytic cells. it produces an atypical lipid a, whose structure precludes an efficient recognition by both innate immune players, tlr4 and cationic antimicrobial peptides. interestingly, a recent report indicates that the lipid a of francisella (lvs vaccinal strain) unde ... | 2017 | 28807561 |
| differential substrate usage and metabolic fluxes in francisella tularensis subspecies holarctica and francisella novicida. | francisella tularensis is an intracellular pathogen for many animals causing the infectious disease, tularemia. whereas f. tularensis subsp. holarctica is highly pathogenic for humans, f. novicida is almost avirulent for humans, but virulent for mice. in order to compare metabolic fluxes between these strains, we performed (13)c-labeling experiments with f. tularensis subsp. holarctica wild type (beaver isolate), f. tularensis subsp. holarctica strain lvs, or f. novicida strain u112 in complex m ... | 2017 | 28680859 |
| glycosylation of a capsule-like complex (clc) by francisella novicida is required for virulence and partial protective immunity in mice. | francisella tularensis is a gram-negative bacterium and the etiologic agent of tularemia. f. tularensis may appear encapsulated when examined by transmission electron microscopy (tem), which is due to production of an extracellular capsule-like complex (clc) when the bacterium is grown under specific environmental conditions. deletion of two glycosylation genes in the live vaccine strain (lvs) results in loss of apparent clc and attenuation of lvs in mice. in contrast, f. novicida, which is also ... | 2017 | 28611741 |
| francisella novicida inhibits spontaneous apoptosis and extends human neutrophil lifespan. | francisella novicida is a gram-negative bacterium that is closely related to the highly virulent facultative intracellular pathogen, francisella tularensis data published by us and others demonstrate that f. tularensis virulence correlates directly with its ability to impair constitutive apoptosis and extend human neutrophil lifespan. in contrast, f. novicida is attenuated in humans, and the mechanisms that account for this are incompletely defined. our published data demonstrate that f. novicid ... | 2017 | 28550119 |
| effects of lipid a acyltransferases on the pathogenesis of f. novicida. | francisella novicida is a gram-negative pathogen commonly used to study infections by the potential bioterrorism agent, francisella tularensis. the francisella lipid a structure has been well characterized and showed to affect the pathogenesis of f. novicida. previous work characterized two lipid a acyltransferases, lpxd1 and lpxd2, and constructed the lpxd1-null and lpxd2-null mutants. mutational analysis showed the lpxd1-null mutant was attenuated in mice and subsequently exhibited protection ... | 2017 | 28478203 |
| crispr-cpf1 assisted genome editing of corynebacterium glutamicum. | corynebacterium glutamicum is an important industrial metabolite producer that is difficult to genetically engineer. although the streptococcus pyogenes (sp) crispr-cas9 system has been adapted for genome editing of multiple bacteria, it cannot be introduced into c. glutamicum. here we report a francisella novicida (fn) crispr-cpf1-based genome-editing method for c. glutamicum. crispr-cpf1, combined with single-stranded dna (ssdna) recombineering, precisely introduces small changes into the bact ... | 2017 | 28469274 |
| identification of conserved abc importers necessary for intracellular survival of legionella pneumophila in multiple hosts. | it is established that the human pathogen legionella pneumophila becomes significantly augmented for infection of macrophages after intracellular growth in amoebae when compared to like-strains cultivated in laboratory media. based on this observation, we reasoned that the most critical virulence determinants of l.p. are expressed by responding to stimuli generated by the protozoan host specifically; a process we term "protozoan-priming." we sought to identify l.p. virulence factors that were re ... | 2017 | 29250489 |
| human caspase-4 detects tetra-acylated lps and cytosolic francisella and functions differently from murine caspase-11. | caspase-4/5 in humans and caspase-11 in mice bind hexa-acylated lipid a, the lipid moeity of lipopolysaccharide (lps), to induce the activation of non-canonical inflammasome. pathogens such as francisella novicida express an under-acylated lipid a and escape caspase-11 recognition in mice. here, we show that caspase-4 drives inflammasome responses to f. novicida infection in human macrophages. caspase-4 triggers f. novicida-mediated, gasdermin d-dependent pyroptosis and activates the nlrp3 infla ... | 2018 | 29339744 |
| establishing rna virus resistance in plants by harnessing crispr immune system. | recently, crispr-cas (clustered, regularly interspaced short palindromic repeats-crispr associated proteins) system has been used to produce plants resistant to dna virus infections. however, there is no rna virus control method in plants that uses crispr-cas system to target the viral genome directly. here we reprogrammed the crispr-cas9 system from francisella novicida to confer molecular immunity against rna viruses in nicotiana benthamiana and arabidopsis plants. plants expressing fncas9 and ... | 2018 | 29327438 |
| detecting release of bacterial dsdna into the host cytosol using fluorescence microscopy. | recognition of pathogens by the innate immune system relies on germline-encoded pattern recognition receptors (prrs) that recognize unique microbial molecules, so-called pathogen-associated molecular patterns (pamps). nucleic acids and their derivatives are one of the most important groups of pamps, and are recognized by a number of surface-associated as well as cytosolic prrs. cyclic gmp-amp synthase (cgas) recognizes the presence of pathogen- or host-derived dsdna in the cytosol and initiates ... | 2018 | 29177864 |
| host-based lipid inflammation drives pathogenesis in francisella infection. | mass spectrometry imaging (msi) was used to elucidate host lipids involved in the inflammatory signaling pathway generated at the host-pathogen interface during a septic bacterial infection. using francisella novicida as a model organism, a bacterial lipid virulence factor (endotoxin) was imaged and identified along with host phospholipids involved in the splenic response in murine tissues. here, we demonstrate detection and distribution of endotoxin in a lethal murine f. novicida infection mode ... | 2017 | 29109289 |
| zinc acquisition mechanisms differ between environmental and virulent francisella species. | zinc is an essential nutrient for bacterial growth. because host cells can restrict pathogen access to zinc as an antimicrobial defense mechanism, intracellular pathogens such as francisella must sense their environment and acquire zinc in response. in many bacteria, the conserved transcription factor zur is a key regulator of zinc acquisition. to identify mechanisms of zinc uptake in francisella novicida u112, transcriptome sequencing of wild-type and putative zur mutant bacteria was performed. ... | 2018 | 29109188 |
| fncpf1: a novel and efficient genome editing tool for saccharomyces cerevisiae. | cpf1 is a new class ii family of crispr-cas rna-programmable endonucleases with unique features that make it a very attractive alternative or complement to cas9 for genome engineering. using constitutively expressed cpf1 from francisella novicida, the present study demonstrates that fncpf1 can mediate rna-guided dna cleavage at targeted genomic loci in the popular model and industrial yeast saccharomyces cerevisiae. fncpf1 very efficiently and precisely promoted repair dna recombination with eff ... | 2017 | 29106617 |
| silkworm model for francisella novicida infection. | understanding the virulence and pathogenesis of human pathogens using insect models is an increasingly popular method. francisella novicida, which is virulent in mice but non-pathogenic to immunocompetent humans, is widely used as an ideal candidate for francisella research. in this study, we developed a silkworm (bombyx mori) infection model for f. novicida by inoculating the hemocoels of silkworms with f. novicida. we found that silkworms died within 3-7 days of f. novicida infection. however, ... | 2017 | 29066381 |
| the metabolic enzyme fructose-1,6-bisphosphate aldolase acts as a transcriptional regulator in pathogenic francisella. | the enzyme fructose-bisphosphate aldolase occupies a central position in glycolysis and gluconeogenesis pathways. beyond its housekeeping role in metabolism, fructose-bisphosphate aldolase has been involved in additional functions and is considered as a potential target for drug development against pathogenic bacteria. here, we address the role of fructose-bisphosphate aldolase in the bacterial pathogen francisella novicida. we demonstrate that fructose-bisphosphate aldolase is important for bac ... | 2017 | 29021545 |
| structure of the conserved francisella virulence protein fvfa. | francisella tularensis is a potent human pathogen that invades and survives in macrophage and epithelial cells. two identical proteins, ftt_0924 from f. tularensis subsp. tularensis and ftl_1286 from f. tularensis subsp. holarctica lvs, have previously been identified as playing a role in protection of the bacteria from osmotic shock and its survival in macrophages. ftt_0924 has been shown to localize to the inner membrane, with its c-terminus exposed to the periplasm. here, crystal structures o ... | 2017 | 28994410 |
| ifn-γ extends the immune functions of guanylate binding proteins to inflammasome-independent antibacterial activities during francisella novicida infection. | guanylate binding proteins (gbps) are interferon-inducible proteins involved in the cell-intrinsic immunity against numerous intracellular pathogens. the molecular mechanisms underlying the potent antibacterial activity of gbps are still unclear. gbps have been functionally linked to the nlrp3, the aim2 and the caspase-11 inflammasomes. two opposing models are currently proposed to explain the gbps-inflammasome link: i) gbps would target intracellular bacteria or bacteria-containing vacuoles to ... | 2017 | 28968459 |
| precise insertion and guided editing of higher plant genomes using cpf1 crispr nucleases. | precise genome editing of plants has the potential to reshape global agriculture through the targeted engineering of endogenous pathways or the introduction of new traits. to develop a crispr nuclease-based platform that would enable higher efficiencies of precise gene insertion or replacement, we screened the cpf1 nucleases from francisella novicida and lachnospiraceae bacterium nd2006 for their capability to induce targeted gene insertion via homology directed repair. both nucleases, in the pr ... | 2017 | 28912524 |
| crispr/cpf1 enables fast and simple genome editing of saccharomyces cerevisiae. | cpf1 represents a novel single rna-guided crispr/cas endonuclease system suitable for genome editing with distinct features compared with cas9. we demonstrate the functionality of three cpf1 orthologues - acidaminococcus spp. bv3l6 (ascpf1), lachnospiraceae bacterium nd2006 (lbcpf1) and francisella novicida u112 (fncpf1) - for genome editing of saccharomyces cerevisiae. these cpf1-based systems enable fast and reliable introduction of donor dna on the genome using a two-plasmid-based editing app ... | 2017 | 28886218 |
| shared features of cryptic plasmids from environmental and pathogenic francisella species. | the francisella genus includes several recognized species, additional potential species, and other representatives that inhabit a range of incredibly diverse ecological niches, but are not closely related to the named species. francisella species have been obtained from a wide variety of clinical and environmental sources; documented species include highly virulent human and animal pathogens, fish pathogens, opportunistic human pathogens, tick endosymbionts, and free-living isolates inhabiting b ... | 2017 | 28837612 |
| assembly of francisella novicida cpf1 endonuclease in complex with guide rna and target dna. | bacteria and archaea use the crispr-cas system as an adaptive response against infection by foreign nucleic acids. owing to its remarkable flexibility, this mechanism has been harnessed and adopted as a powerful tool for genome editing. the crispr-cas system includes two classes that are subdivided into six types and 19 subtypes according to conservation of the cas gene and loci organization. recently, a new protein with endonuclease activity belonging to class 2 type v has been identified. this ... | 2017 | 28695850 |
| structure of the cpf1 endonuclease r-loop complex after target dna cleavage. | cpf1 is an rna-guided endonuclease that is emerging as a powerful genome-editing tool. here we provide insight into its dna-targeting mechanism by determining the structure of francisella novicida cpf1 with the triple-stranded r-loop generated after dna cleavage. the structure reveals the machinery involved in dna unwinding to form a crispr rna (crrna)-dna hybrid and a displaced dna strand. the protospacer adjacent motif (pam) is recognized by the pam-interacting domain. the loop-lysine helix-lo ... | 2017 | 28562584 |
| structural basis for guide rna processing and seed-dependent dna targeting by crispr-cas12a. | the crispr-associated protein cas12a (cpf1), which has been repurposed for genome editing, possesses two distinct nuclease activities: endoribonuclease activity for processing its own guide rnas and rna-guided dnase activity for target dna cleavage. to elucidate the molecular basis of both activities, we determined crystal structures of francisella novicida cas12a bound to guide rna and in complex with an r-loop formed by a non-cleavable guide rna precursor and a full-length target dna. corrobor ... | 2017 | 28431230 |
| targeted activation of diverse crispr-cas systems for mammalian genome editing via proximal crispr targeting. | bacterial crispr-cas systems comprise diverse effector endonucleases with different targeting ranges, specificities and enzymatic properties, but many of them are inactive in mammalian cells and are thus precluded from genome-editing applications. here we show that the type ii-b fncas9 from francisella novicida possesses novel properties, but its nuclease function is frequently inhibited at many genomic loci in living human cells. moreover, we develop a proximal crispr (termed proxy-crispr) targ ... | 2017 | 28387220 |
| functional characterization of the dna gyrases in fluoroquinolone-resistant mutants of francisella novicida. | fluoroquinolone (fq) resistance is a major health concern in the treatment of tularemia. because dna gyrase has been described as the main target of these compounds, our aim was to clarify the contributions of both gyra and gyrb mutations found in francisella novicida clones highly resistant to fqs. wild-type and mutated gyra and gyrb subunits were overexpressed so that the in vitro fq sensitivity of functional reconstituted complexes could be evaluated. the data obtained were compared to the mi ... | 2017 | 28167561 |
| nkg2d promotes b1a cell development and protection against bacterial infection. | nkg2d is a potent activating receptor that is expressed on cytotoxic immune cells such as cd8 t and nk cells, where it promotes cytotoxicity after binding stress ligands on infected or transformed cells. on nk cell precursors nkg2d modulates proliferation and maturation. previously, we observed that nkg2d deficiency affects peripheral b cell numbers. in this study, we show that nkg2d regulates b1a cell development and function. we find that mice deficient for nkg2d have a strong reduction of b1a ... | 2017 | 28087665 |
| regulation of lysosomal dynamics and autophagy by ctsb/cathepsin b. | cysteine cathepsins are responsible for driving proteolytic degradation within the lysosome and in the extralysosomal milieu. they also have an integral role in autophagy, antigen presentation, cellular stress signaling, metabolism and lysosome-dependent cell death. here, we discuss our findings on the role of ctsb (cathepsin b), a member of the cysteine cathepsin family, in regulating the bioavailability of lysosomes and autophagosomes and consider how this regulatory response influences host s ... | 2016 | 27786577 |
| irgb10 liberates bacterial ligands for sensing by the aim2 and caspase-11-nlrp3 inflammasomes. | the inflammasome is an intracellular signaling complex, which on recognition of pathogens and physiological aberration, drives activation of caspase-1, pyroptosis, and the release of the pro-inflammatory cytokines il-1β and il-18. bacterial ligands must secure entry into the cytoplasm to activate inflammasomes; however, the mechanisms by which concealed ligands are liberated in the cytoplasm have remained unclear. here, we showed that the interferon-inducible protein irgb10 is essential for acti ... | 2016 | 27693356 |
| norharmane matrix enhances detection of endotoxin by maldi-ms for simultaneous profiling of pathogen, host, and vector systems. | the discovery of novel pathogenic mechanisms engaged during bacterial infections requires the evolution of advanced techniques. here, we evaluate the dual polarity matrix norharmane (nrm) to improve detection of bacterial lipid a (endotoxin), from host and vector tissues infected with francisella novicida (fn). we evaluated nrm for improved detection and characterization of a wide range of lipids in both positive and negative polarities, including lipid a and phospholipids across a range of matr ... | 2016 | 27650574 |
| rapid lipid a structure determination via surface acoustic wave nebulization and hierarchical tandem mass spectrometry algorithm. | surface acoustic wave nebulization (sawn) is an easy to use sample transfer method for rapid mass spectrometric analysis. a new standing wave (sw) sawn chip, with higher ionization efficiency than our previously reported design, is used for rapid analysis of lipids. | 2016 | 27582344 |
| cathepsin b modulates lysosomal biogenesis and host defense against francisella novicida infection. | lysosomal cathepsins regulate an exquisite range of biological functions, and their deregulation is associated with inflammatory, metabolic, and degenerative diseases in humans. in this study, we identified a key cell-intrinsic role for cathepsin b as a negative feedback regulator of lysosomal biogenesis and autophagy. mice and macrophages lacking cathepsin b activity had increased resistance to the cytosolic bacterial pathogen francisella novicida genetic deletion or pharmacological inhibition ... | 2016 | 27551156 |
| the crispr-associated dna-cleaving enzyme cpf1 also processes precursor crispr rna. | crispr-cas systems that provide defence against mobile genetic elements in bacteria and archaea have evolved a variety of mechanisms to target and cleave rna or dna. the well-studied types i, ii and iii utilize a set of distinct crispr-associated (cas) proteins for production of mature crispr rnas (crrnas) and interference with invading nucleic acids. in types i and iii, cas6 or cas5d cleaves precursor crrna (pre-crrna) and the mature crrnas then guide a complex of cas proteins (cascade-cas3, ty ... | 2016 | 27096362 |
| comparative analyses of a putative francisella conjugative element. | a large circular plasmid detected in francisella novicida-like strain pa10-7858, designated pfnpa10, was sequenced completely and analyzed. this 41,013-bp plasmid showed no homology to any of the previously sequenced francisella plasmids and was 8-10 times larger in size than them. a total of 57 orfs were identified within pfnpa10 and at least 9 of them encoded putative proteins with homology to different conjugal transfer proteins. the presence of iteron-like direct repeats and an orf encoding ... | 2014 | 24884689 |
| cas9-dependent endogenous gene regulation is required for bacterial virulence. | crispr (clustered regularly interspaced short palindromic repeats)-cas (crispr-associated) systems are known to mediate bacterial defence against foreign nucleic acids. we recently demonstrated a non-canonical role for a crispr-cas system in controlling endogenous gene expression, which had not previously been appreciated. in the present article, we describe the studies that led to this discovery, beginning with an unbiased genome-wide screen to identify virulence genes in the intracellular path ... | 2013 | 24256228 |
| the structure of the conserved type six secretion protein tssl (dotu) from francisella novicida. | type six secretion systems (t6sss) are found in many gram-negative bacteria and are important for their virulence or their ecological competitiveness. the multicomponent t6sss are responsible for the translocation of effector molecules into target eukaryotic or prokaryotic cells. the francisella pathogenicity island encodes a putative t6ss that francisella novicida requires for intramacrophage growth and virulence during infection of rodents. here, we present the x-ray crystal structure of the c ... | 2012 | 22504227 |