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1.
Anaerobe ; 82: 102760, 2023 Aug.
Article in English | MEDLINE | ID: mdl-37451427

ABSTRACT

OBJECTIVES: Many bacterial species naturally take up DNA from their surroundings and recombine it into their chromosome through homologous gene transfer (HGT) to aid in survival and gain advantageous functions. Herein we present the first characterization of Type IV pili facilitated natural competence in Fusobacterium nucleatum, which is a Gram-negative, anaerobic bacterium that participates in a range of infections and diseases including periodontitis, preterm birth, and cancer. METHODS: Here we used bioinformatics on multiple Fusobacterium species, as well as molecular genetics to characterize natural competence in strain F. nucleatum subsp. nucleatum ATCC 23726. RESULTS: We bioinformatically identified components of the Type IV conjugal pilus machinery and show this is a conserved system within the Fusobacterium genus. We next validate Type IV pili in natural competence in F. nucleatum ATCC 23726 and show that gene deletions in key components of pilus deployment (pilQ) and cytoplasmic DNA import (comEC) abolish DNA uptake and chromosomal incorporation. We next show that natural competence may require native F. nucleatum DNA methylation to bypass restriction modification systems and allow subsequent genomic homologous recombination. CONCLUSIONS: In summary, this proof of principle study provides the first characterization of natural competence in Fusobacterium nucleatum and highlights the potential to exploit this DNA import mechanism as a genetic tool to characterize virulence mechanisms of an opportunistic oral pathogen.


Subject(s)
Fusobacterium Infections , Premature Birth , Infant, Newborn , Humans , Female , Fusobacterium nucleatum/metabolism , Base Composition , Sequence Analysis, DNA , Phylogeny , RNA, Ribosomal, 16S , Fusobacterium , DNA, Bacterial/genetics , Fusobacterium Infections/microbiology
2.
J Bacteriol ; 204(12): e0027922, 2022 12 20.
Article in English | MEDLINE | ID: mdl-36326270

ABSTRACT

Bacterial restriction-modification (R-M) systems are a first-line immune defense against foreign DNA from viruses and other bacteria. While R-M systems are critical in maintaining genome integrity, R-M nucleases unfortunately present significant barriers to targeted genetic modification. Bacteria of the genus Fusobacterium are oral, Gram-negative, anaerobic, opportunistic pathogens that are implicated in the progression and severity of multiple cancers and tissue infections, yet our understanding of their direct roles in disease have been severely hindered by their genetic recalcitrance. Here, we demonstrate a path to overcome these barriers in Fusobacterium by using native DNA methylation as a host mimicry strategy to bypass R-M system cleavage of transformed plasmid DNA. We report the identification, characterization, and successful use of Fusobacterium nucleatum type II and III DNA methyltransferase (MTase) enzymes to produce a multifold increase in gene knockout efficiency in the strain Fusobacterium nucleatum subsp. nucleatum 23726, as well as the first system for efficient gene knockouts and complementations in F. nucleatum subsp. nucleatum 25586. We show plasmid protection can be accomplished in vitro with purified enzymes, as well as in vivo in an Escherichia coli host that constitutively expresses F. nucleatum subsp. nucleatum MTase enzymes. In summary, this proof-of-concept study characterizes specific MTases that are critical for bypassing R-M systems and has enhanced our understanding of enzyme combinations that could be used to genetically modify clinical isolates of Fusobacterium that have thus far been inaccessible to molecular characterization. IMPORTANCE Fusobacterium nucleatum is an oral opportunistic pathogen associated with diseases that include cancer and preterm birth. Our understanding of how this bacterium modulates human disease has been hindered by a lack of genetic systems. Here, we show that F. nucleatum DNA methyltransferase-modified plasmid DNA overcomes the transformation barrier and has allowed the development of a genetic system in a previously inaccessible strain. We present a strategy that could potentially be expanded to enable the genetic modification of highly recalcitrant strains, thereby fostering investigational studies to uncover novel host-pathogen interactions in Fusobacterium.


Subject(s)
DNA Restriction-Modification Enzymes , Fusobacterium nucleatum , Methyltransferases , DNA Methylation , DNA Restriction-Modification Enzymes/genetics , Fusobacterium nucleatum/genetics , Methyltransferases/genetics
3.
Biochem J ; 476(18): 2657-2676, 2019 09 24.
Article in English | MEDLINE | ID: mdl-31492736

ABSTRACT

Autotransporters, or type 5 secretion systems, are widespread surface proteins of Gram-negative bacteria often associated with virulence functions. Autotransporters consist of an outer membrane ß-barrel domain and an exported passenger. In the poorly studied type 5d subclass, the passenger is a patatin-like lipase. The prototype of this secretion pathway is PlpD of Pseudomonas aeruginosa, an opportunistic human pathogen. The PlpD passenger is a homodimer with phospholipase A1 (PLA1) activity. Based on sequencing data, PlpD-like proteins are present in many bacterial species. We characterized the enzymatic activity, specific lipid binding and oligomeric status of PlpD homologs from Aeromonas hydrophila (a fish pathogen), Burkholderia pseudomallei (a human pathogen) and Ralstonia solanacearum (a plant pathogen) and compared these with PlpD. We demonstrate that recombinant type 5d-secreted patatin domains have lipase activity and form dimers or higher-order oligomers. However, dimerization is not necessary for lipase activity; in fact, by making monomeric variants of PlpD, we show that enzymatic activity slightly increases while protein stability decreases. The lipases from the intracellular pathogens A. hydrophila and B. pseudomallei display PLA2 activity in addition to PLA1 activity. Although the type 5d-secreted lipases from the animal pathogens bound to intracellular lipid targets, phosphatidylserine and phosphatidylinositol phosphates, hydrolysis of these lipids could only be observed for FplA of Fusobacterium nucleatum Yet, we noted a correlation between high lipase activity in type 5d autotransporters and intracellular lifestyle. We hypothesize that type 5d phospholipases are intracellularly active and function in modulation of host cell signaling events.


Subject(s)
Bacteria/metabolism , Bacteria/pathogenicity , Bacterial Proteins/metabolism , Bacterial Secretion Systems/metabolism , Lipase/metabolism , Virulence Factors/metabolism , Bacteria/genetics , Bacterial Proteins/genetics , Bacterial Secretion Systems/genetics , Humans , Lipase/genetics , Protein Transport/physiology , Signal Transduction/physiology , Virulence Factors/genetics
4.
J Bacteriol ; 201(23)2019 12 01.
Article in English | MEDLINE | ID: mdl-31501282

ABSTRACT

Fusobacterium spp. are Gram-negative, anaerobic, opportunistic pathogens involved in multiple diseases, including a link between the oral pathogen Fusobacterium nucleatum and the progression and severity of colorectal cancer. The identification and characterization of virulence factors in the genus Fusobacterium has been greatly hindered by a lack of properly assembled and annotated genomes. Using newly completed genomes from nine strains and seven species of Fusobacterium, we report the identification and corrected annotation of verified and potential virulence factors from the type 5 secreted autotransporter, FadA, and MORN2 protein families, with a focus on the genetically tractable strain F. nucleatum subsp. nucleatum ATCC 23726 and type strain F. nucleatum subsp. nucleatum ATCC 25586. Within the autotransporters, we used sequence similarity networks to identify protein subsets and show a clear differentiation between the prediction of outer membrane adhesins, serine proteases, and proteins with unknown function. These data have identified unique subsets of type 5a autotransporters, which are key proteins associated with virulence in F. nucleatum However, we coupled our bioinformatic data with bacterial binding assays to show that a predicted weakly invasive strain of F. necrophorum that lacks a Fap2 autotransporter adhesin strongly binds human colonocytes. These analyses confirm a gap in our understanding of how autotransporters, MORN2 domain proteins, and FadA adhesins contribute to host interactions and invasion. In summary, we identify candidate virulence genes in Fusobacterium, and caution that experimental validation of host-microbe interactions should complement bioinformatic predictions to increase our understanding of virulence protein contributions in Fusobacterium infections and disease.IMPORTANCEFusobacterium spp. are emerging pathogens that contribute to mammalian and human diseases, including colorectal cancer. Despite a validated connection with disease, few proteins have been characterized that define a direct molecular mechanism for Fusobacterium pathogenesis. We report a comprehensive examination of virulence-associated protein families in multiple Fusobacterium species and show that complete genomes facilitate the correction and identification of multiple, large type 5a secreted autotransporter genes in previously misannotated or fragmented genomes. In addition, we use protein sequence similarity networks and human cell interaction experiments to show that previously predicted noninvasive strains can indeed bind to and potentially invade human cells and that this could be due to the expansion of specific virulence proteins that drive Fusobacterium infections and disease.


Subject(s)
Adhesins, Bacterial/genetics , Fusobacterium/genetics , Fusobacterium/pathogenicity , Genome, Bacterial , Type V Secretion Systems/genetics , Virulence Factors/genetics , Adhesins, Bacterial/classification , Adhesins, Bacterial/metabolism , Amino Acid Sequence , Bacterial Adhesion , Cell Line , Computational Biology/methods , Epithelial Cells/microbiology , Epithelial Cells/pathology , Fusobacterium/classification , Fusobacterium/metabolism , Fusobacterium Infections/microbiology , Fusobacterium Infections/pathology , Gene Expression , Gingiva/microbiology , Gingiva/pathology , HCT116 Cells , Humans , Phylogeny , Sequence Alignment , Sequence Homology, Amino Acid , Type V Secretion Systems/classification , Type V Secretion Systems/metabolism , Virulence , Virulence Factors/classification , Virulence Factors/metabolism
5.
Biochemistry ; 58(27): 3042-3056, 2019 07 09.
Article in English | MEDLINE | ID: mdl-31243954

ABSTRACT

Protein arginine deiminases (PADs) are calcium-dependent enzymes that mediate the post-translational conversion of arginine into citrulline. Dysregulated PAD activity is associated with numerous autoimmune disorders and cancers. In breast cancer, PAD2 citrullinates histone H3R26 and activates the transcription of estrogen receptor target genes. However, PAD2 lacks a canonical nuclear localization sequence, and it is unclear how this enzyme is transported into the nucleus. Here, we show for the first time that PAD2 translocates into the nucleus in response to calcium signaling. Using BioID2, a proximity-dependent biotinylation method for identifying interacting proteins, we found that PAD2 preferentially associates with ANXA5 in the cytoplasm. Binding of calcium to PAD2 weakens this cytoplasmic interaction, which generates a pool of calcium-bound PAD2 that can interact with Ran. We hypothesize that this latter interaction promotes the translocation of PAD2 into the nucleus. These findings highlight a critical role for ANXA5 in regulating PAD2 and identify an unusual mechanism whereby proteins translocate between the cytosol and nucleus.


Subject(s)
Calcium/metabolism , Cell Nucleus/metabolism , Protein-Arginine Deiminase Type 2/metabolism , Active Transport, Cell Nucleus , Calcium Signaling , HEK293 Cells , Humans , Models, Molecular , Protein-Arginine Deiminase Type 2/analysis
6.
J Biol Chem ; 292(49): 20240-20254, 2017 12 08.
Article in English | MEDLINE | ID: mdl-29021252

ABSTRACT

Fusobacterium nucleatum is an oral pathogen that is linked to multiple human infections and colorectal cancer. Strikingly, F. nucleatum achieves virulence in the absence of large, multiprotein secretion systems (Types I, II, III, IV, and VI), which are widely used by Gram-negative bacteria for pathogenesis. By contrast, F. nucleatum strains contain genomic expansions of Type V secreted effectors (autotransporters) that are critical for host cell adherence, invasion, and biofilm formation. Here, we present the first characterization of an F. nucleatum Type Vd phospholipase class A1 autotransporter (strain ATCC 25586, gene FN1704) that we hereby rename Fusobacterium phospholipase autotransporter (FplA). Biochemical analysis of multiple Fusobacterium strains revealed that FplA is expressed as a full-length 85-kDa outer membrane-embedded protein or as a truncated phospholipase domain that remains associated with the outer membrane. Whereas the role of Type Vd secretion in bacteria remains unidentified, we show that FplA binds with high affinity to host phosphoinositide-signaling lipids, revealing a potential role for this enzyme in establishing an F. nucleatum intracellular niche. To further analyze the role of FplA, we developed an fplA gene knock-out strain, which will guide future in vivo studies to determine its potential role in F. nucleatum pathogenesis. In summary, using recombinant FplA constructs, we have identified a biochemical toolbox that includes lipid substrates for enzymatic assays, potent inhibitors, and chemical probes to detect, track, and characterize the role of Type Vd secreted phospholipases in Gram-negative bacteria.


Subject(s)
Fusobacterium nucleatum/enzymology , Phospholipases A1/chemistry , Type V Secretion Systems/chemistry , Bacterial Proteins , Fusobacterium nucleatum/pathogenicity , Membrane Proteins , Phosphatidylinositols , Phospholipases A1/metabolism , Phospholipases A1/physiology , Virulence
7.
Nat Chem Biol ; 11(3): 189-91, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25622091

ABSTRACT

PAD4 has been strongly implicated in the pathogenesis of autoimmune, cardiovascular and oncological diseases through clinical genetics and gene disruption in mice. New selective PAD4 inhibitors binding a calcium-deficient form of the PAD4 enzyme have validated the critical enzymatic role of human and mouse PAD4 in both histone citrullination and neutrophil extracellular trap formation for, to our knowledge, the first time. The therapeutic potential of PAD4 inhibitors can now be explored.


Subject(s)
Benzimidazoles/pharmacology , Enzyme Inhibitors/pharmacology , Hydrolases/antagonists & inhibitors , Neutrophils/drug effects , Animals , Benzimidazoles/chemical synthesis , Binding, Competitive , Calcium/metabolism , Citrulline/metabolism , Enzyme Inhibitors/chemical synthesis , HEK293 Cells , Histones/metabolism , Humans , In Vitro Techniques , Mice , Models, Molecular , Protein-Arginine Deiminase Type 4 , Protein-Arginine Deiminases , Small Molecule Libraries , Substrate Specificity
8.
Bioessays ; 36(8): 736-40, 2014 Aug.
Article in English | MEDLINE | ID: mdl-24889365

ABSTRACT

Histone post-translational modifications (PTMs) alter the chromatin architecture, generating "open" and "closed" states, and these structural changes can modulate gene expression under specific cellular conditions. While methylation and acetylation are the best-characterized histone PTMs, citrullination by the protein arginine deiminases (PADs) represents another important player in this process. In addition to "fine tuning" chromatin structure at specific loci, histone citrullination can also promote rapid global chromatin decondensation during the formation of extracellular traps (ETs) in immune cells. Recent studies now show that PAD4-mediated citrullination of histone H1 at promoter elements can also promote localized chromatin decondensation in stem cells, thus regulating the pluripotent state. These observations suggest that PAD-mediated histone deimination profoundly affects chromatin structure, possibly above and beyond that of other PTMs. Additionally, these recent findings further enhance our understanding of PAD biology and the important contributions that these enzymes play in development, health, and disease.


Subject(s)
Histones/metabolism , Hydrolases/physiology , Induced Pluripotent Stem Cells/enzymology , Animals , Arthritis, Rheumatoid/enzymology , Cellular Reprogramming , Chromatin Assembly and Disassembly , Citrulline/metabolism , Humans , Protein Processing, Post-Translational , Protein-Arginine Deiminase Type 4 , Protein-Arginine Deiminases , Transcription Factors/genetics , Transcription Factors/metabolism , Transcription, Genetic
9.
Proc Natl Acad Sci U S A ; 109(33): 13331-6, 2012 Aug 14.
Article in English | MEDLINE | ID: mdl-22853951

ABSTRACT

Cofactors for estrogen receptor α (ERα) can modulate gene activity by posttranslationally modifying histone tails at target promoters. Here, we found that stimulation of ERα-positive cells with 17ß-estradiol (E2) promotes global citrullination of histone H3 arginine 26 (H3R26) on chromatin. Additionally, we found that the H3 citrulline 26 (H3Cit26) modification colocalizes with ERα at decondensed chromatin loci surrounding the estrogen-response elements of target promoters. Surprisingly, we also found that citrullination of H3R26 is catalyzed by peptidylarginine deiminase (PAD) 2 and not by PAD4 (which citrullinates H4R3). Further, we showed that PAD2 interacts with ERα after E2 stimulation and that inhibition of either PAD2 or ERα strongly suppresses E2-induced H3R26 citrullination and ERα recruitment at target gene promoters. Collectively, our data suggest that E2 stimulation induces the recruitment of PAD2 to target promoters by ERα, whereby PAD2 then citrullinates H3R26, which leads to local chromatin decondensation and transcriptional activation.


Subject(s)
Arginine/metabolism , Biocatalysis , Citrulline/metabolism , Estrogen Receptor alpha/metabolism , Histones/metabolism , Hydrolases/metabolism , Transcriptional Activation , Animals , Biocatalysis/drug effects , Cell Line, Tumor , Chromatin/metabolism , Estrogens/pharmacology , Gene Expression Regulation, Neoplastic/drug effects , Genome, Human/genetics , Humans , Mice , Nucleotide Motifs/genetics , Promoter Regions, Genetic/genetics , Protein-Arginine Deiminase Type 2 , Protein-Arginine Deiminases , Response Elements/genetics , Transcription, Genetic/drug effects , Transcriptional Activation/drug effects
10.
Biopolymers ; 101(2): 133-43, 2014 Feb.
Article in English | MEDLINE | ID: mdl-23576281

ABSTRACT

Post-translational modifications (PTMs) of protein embedded arginines are increasingly being recognized as playing an important role in both prokaryotic and eukaryotic biology, and it is now clear that these PTMs modulate a number of cellular processes including DNA binding, gene transcription, protein-protein interactions, immune system activation, and proteolysis. There are currently four known enzymatic PTMs of arginine (i.e., citrullination, methylation, phosphorylation, and ADP-ribosylation), and two non-enzymatic PTMs [i.e., carbonylation, advanced glycation end-products (AGEs)]. Enzymatic modification of arginine is tightly controlled during normal cellular function, and can be drastically altered in response to various second messengers and in different disease states. Non-enzymatic arginine modifications are associated with a loss of metabolite regulation during normal human aging. This abnormally large number of modifications to a single amino acid creates a diverse set of structural perturbations that can lead to altered biological responses. While the biological role of methylation has been the most extensively characterized of the arginine PTMs, recent advances have shown that the once obscure modification known as citrullination is involved in the onset and progression of inflammatory diseases and cancer. This review will highlight the reported arginine PTMs and their methods of detection, with a focus on new chemical methods to detect protein citrullination.


Subject(s)
Arginine/metabolism , Protein Processing, Post-Translational , Animals , Antibodies/metabolism , Citrulline/metabolism , Fluorescent Dyes/metabolism , Humans , Peptides/metabolism
11.
Bioelectrochemistry ; 157: 108669, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38377890

ABSTRACT

Intratumoral bacteria have been implicated in driving tumor progression, yet effective treatments to modulate the tumor microbiome remain limited. In this study, we investigate the use of electroporation in combination with metronidazole to enhance the clearance of intracellular Fusobacterium nucleatum within pancreatic cancer cells. We explore various parameters, including electric field strength, pulse width, and pulse number to assess the permeability of pancreatic cancer cells infected with F. nucleatum, compared to non-infected cells of the same type. We subsequently quantify the clearance of intracellular bacteria when these pulsing schemes are applied to a suspension of infected pancreatic cancer cells in the presence of metronidazole. Our results reveal distinct differences in cell permeability between infected and non-infected cells, identifying a unique biophysical marker for host cells infected with F. nucleatum. We demonstrate that the combinatorial use of electroporation and metronidazole significantly enhances the delivery of metronidazole into host cells, leading to more effective clearance of intracellular F. nucleatum compared to independent treatments; we term this novel approach Electro-Antibacterial Therapy (EAT). EAT holds promise as an innovative strategy for addressing intratumoral bacteria in pancreatic cancer, other malignancies, and potentially treatment-resistant infections, offering new avenues for therapeutic intervention.


Subject(s)
Metronidazole , Pancreatic Neoplasms , Humans , Metronidazole/pharmacology , Metronidazole/therapeutic use , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/therapeutic use , Fusobacterium nucleatum , Pancreatic Neoplasms/drug therapy
12.
Commun Biol ; 7(1): 551, 2024 May 08.
Article in English | MEDLINE | ID: mdl-38720110

ABSTRACT

Fusobacterium nucleatum, a gram-negative oral bacterium, has been consistently validated as a strong contributor to the progression of several types of cancer, including colorectal (CRC) and pancreatic cancer. While previous in vitro studies have shown that intracellular F. nucleatum enhances malignant phenotypes such as cell migration, the dependence of this regulation on features of the tumor microenvironment (TME) such as oxygen levels are wholly uncharacterized. Here we examine the influence of hypoxia in facilitating F. nucleatum invasion and its effects on host responses focusing on changes in the global epigenome and transcriptome. Using a multiomic approach, we analyze epigenomic alterations of H3K27ac and global transcriptomic alterations sustained within a hypoxia and normoxia conditioned CRC cell line HCT116 at 24 h following initial infection with F. nucleatum. Our findings reveal that intracellular F. nucleatum activates signaling pathways and biological processes in host cells similar to those induced upon hypoxia conditioning in the absence of infection. Furthermore, we show that a hypoxic TME favors F. nucleatum invasion and persistence and therefore infection under hypoxia may amplify malignant transformation by exacerbating the effects induced by hypoxia alone. These results motivate future studies to investigate host-microbe interactions in tumor tissue relevant conditions that more accurately define parameters for targeted cancer therapies.


Subject(s)
Colorectal Neoplasms , Epigenome , Fusobacterium Infections , Fusobacterium nucleatum , Oxygen , Transcriptome , Humans , Fusobacterium nucleatum/genetics , Fusobacterium nucleatum/physiology , Fusobacterium nucleatum/pathogenicity , Colorectal Neoplasms/genetics , Colorectal Neoplasms/microbiology , Colorectal Neoplasms/metabolism , Colorectal Neoplasms/pathology , HCT116 Cells , Fusobacterium Infections/genetics , Fusobacterium Infections/microbiology , Fusobacterium Infections/metabolism , Oxygen/metabolism , Tumor Microenvironment/genetics , Gene Expression Regulation, Neoplastic
13.
Gut Microbes ; 16(1): 2350149, 2024.
Article in English | MEDLINE | ID: mdl-38709233

ABSTRACT

Mucinous colorectal cancer (CRC) is a common histological subtype of colorectal adenocarcinoma, associated with a poor response to chemoradiotherapy. The commensal facultative anaerobes fusobacteria, have been associated with poor prognosis specifically in mesenchymal CRC. Interestingly, fusobacterial infection is especially prevalent in mucinous CRC. The objective of this study was therefore to increase our understanding of beneficial and detrimental effects of fusobacterial infection, by contrasting host cell signaling and immune responses in areas of high vs. low infection, using mucinous rectal cancer as a clinically relevant example. We employed spatial transcriptomic profiling of 106 regions of interest from 8 mucinous rectal cancer samples to study gene expression in the epithelial and immune segments across regions of high versus low fusobacterial infection. Fusobacteria high regions were associated with increased oxidative stress, DNA damage, and P53 signaling. Meanwhile regions of low fusobacterial prevalence were characterized by elevated JAK-STAT, Il-17, Il-1, chemokine and TNF signaling. Immune masks within fusobacterial high regions were characterized by elevated proportions of cytotoxic (CD8+) T cells (p = 0.037), natural killer (NK) cells (p < 0.001), B-cells (p < 0.001), and gamma delta T cells (p = 0.003). Meanwhile, fusobacteria low regions were associated with significantly greater M2 macrophage (p < 0.001), fibroblast (p < 0.001), pericyte (p = 0.002), and endothelial (p < 0.001) counts.


Subject(s)
DNA Damage , Gene Expression Profiling , Rectal Neoplasms , Signal Transduction , Humans , Rectal Neoplasms/genetics , Rectal Neoplasms/immunology , Rectal Neoplasms/microbiology , Male , Female , Middle Aged , Transcriptome , Aged
14.
J Mol Med (Berl) ; 101(7): 829-841, 2023 07.
Article in English | MEDLINE | ID: mdl-37171483

ABSTRACT

There is currently an urgent need to identify factors predictive of immunogenicity in colorectal cancer (CRC). Mucinous CRC is a distinct histological subtype of CRC, associated with a poor response to chemotherapy. Recent evidence suggests the commensal facultative anaerobe Fusobacterium may be especially prevalent in mucinous CRC. The objectives of this study were to assess the association of Fusobacterium abundance with immune cell composition and prognosis in mucinous CRC. Our study included two independent colorectal cancer patient cohorts, The Cancer Genome Atlas (TCGA) cohort, and a cohort of rectal cancers from the Beaumont RCSI Cancer Centre (BRCC). Multiplexed immunofluorescence staining of a tumour microarray (TMA) from the BRCC cohort was undertaken using Cell DIVE technology. Our cohorts included 87 cases (13.3%) of mucinous and 565 cases (86.7%) of non-mucinous CRC. Mucinous CRC in the TCGA dataset was associated with an increased proportion of CD8 + lymphocytes (p = 0.018), regulatory T-cells (p = 0.001) and M2 macrophages (p = 0.001). In the BRCC cohort, mucinous RC was associated with enhanced CD8 + lymphocyte (p = 0.022), regulatory T-cell (p = 0.047), and B-cell (p = 0.025) counts. High Fusobacterium abundance was associated with an increased proportion of CD4 + lymphocytes (p = 0.031) and M1 macrophages (p = 0.006), whilst M2 macrophages (p = 0.043) were under-represented in this cohort. Patients with increased Fusobacterium relative abundance in our mucinous CRC TCGA cohort tended to have better clinical outcomes (DSS: likelihood ratio p = 0.04, logrank p = 0.052). Fusobacterium abundance may be associated with improved outcomes in mucinous CRC, possibly due to a modulatory effect on the host immune response. KEY MESSAGES: • Increased Fusobacterium relative abundance was not found to be associated with microsatellite instability in mucinous CRC. • Increased Fusobacterium relative abundance was associated with an M2/M1 macrophage switch, which is especially significant in mucinous CRC, where M2 macrophages are overexpressed. • Increased Fusobacterium relative abundance was associated with a significant improvement in disease specific survival in mucinous CRC. • Our findings were validated at a protein level within our own in house mucinous and non-mucinous rectal cancer cohorts.


Subject(s)
Colorectal Neoplasms , Rectal Neoplasms , Humans , Fusobacterium/genetics , Colorectal Neoplasms/metabolism , Microsatellite Instability , Macrophages/metabolism
15.
mBio ; 13(3): e0127022, 2022 06 28.
Article in English | MEDLINE | ID: mdl-35638611

ABSTRACT

The type III secretion system is required for virulence of many pathogenic bacteria. Bacterial effector proteins delivered into target host cells by this system modulate host signaling pathways and processes in a manner that promotes infection. Here, we define the activity of the effector protein OspB of the human pathogen Shigella spp., the etiological agent of shigellosis and bacillary dysentery. Using the yeast Saccharomyces cerevisiae as a model organism, we show that OspB sensitizes cells to inhibition of TORC1, the central regulator of growth and metabolism. In silico analyses reveal that OspB bears structural homology to bacterial cysteine proteases that target mammalian cell processes, and we define a conserved cysteine-histidine catalytic dyad required for OspB function. Using yeast genetic screens, we identify a crucial role for the arginine N-degron pathway in the yeast growth inhibition phenotype and show that inositol hexakisphosphate is an OspB cofactor. We find that a yeast substrate for OspB is the TORC1 component Tco89p, proteolytic cleavage of which generates a C-terminal fragment that is targeted for degradation via the arginine N-degron pathway; processing and degradation of Tco89p is required for the OspB phenotype. In all, we demonstrate that the Shigella T3SS effector OspB is a cysteine protease and decipher its interplay with eukaryotic cell processes. IMPORTANCEShigella spp. are important human pathogens and among the leading causes of diarrheal mortality worldwide, especially in children. Virulence depends on the Shigella type III secretion system (T3SS). Definition of the roles of the bacterial effector proteins secreted by the T3SS is key to understanding Shigella pathogenesis. The effector protein OspB contributes to a range of phenotypes during infection, yet the mechanism of action is unknown. Here, we show that S. flexneri OspB possesses cysteine protease activity in both yeast and mammalian cells, and that enzymatic activity of OspB depends on a conserved cysteine-histidine catalytic dyad. We determine how its protease activity sensitizes cells to TORC1 inhibition in yeast, finding that OspB cleaves a component of yeast TORC1, and that the degradation of the C-terminal cleavage product is responsible for OspB-mediated hypersensitivity to TORC1 inhibitors. Thus, OspB is a cysteine protease that depends on a conserved cysteine-histidine catalytic dyad.


Subject(s)
Cysteine Proteases , Dysentery, Bacillary , Shigella , Animals , Arginine/metabolism , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Cysteine/metabolism , Cysteine Proteases/genetics , Cysteine Proteases/metabolism , Histidine/metabolism , Mammals/metabolism , Mechanistic Target of Rapamycin Complex 1 , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Shigella/physiology , Shigella flexneri/metabolism , Type III Secretion Systems/genetics , Type III Secretion Systems/metabolism
16.
Sci Signal ; 15(756): eabn4948, 2022 10 18.
Article in English | MEDLINE | ID: mdl-36256708

ABSTRACT

The tumor microbiome is increasingly implicated in cancer progression and resistance to chemotherapy. In pancreatic ductal adenocarcinoma (PDAC), high intratumoral loads of Fusobacterium nucleatum correlate with shorter survival in patients. Here, we investigated the potential mechanisms underlying this association. We found that F. nucleatum infection induced both normal pancreatic epithelial cells and PDAC cells to secrete increased amounts of the cytokines GM-CSF, CXCL1, IL-8, and MIP-3α. These cytokines increased proliferation, migration, and invasive cell motility in both infected and noninfected PDAC cells but not in noncancerous pancreatic epithelial cells, suggesting autocrine and paracrine signaling to PDAC cells. This phenomenon occurred in response to Fusobacterium infection regardless of the strain and in the absence of immune and other stromal cells. Blocking GM-CSF signaling markedly limited proliferative gains after infection. Thus, F. nucleatum infection in the pancreas elicits cytokine secretion from both normal and cancerous cells that promotes phenotypes in PDAC cells associated with tumor progression. The findings support the importance of exploring host-microbe interactions in pancreatic cancer to guide future therapeutic interventions.


Subject(s)
Carcinoma, Pancreatic Ductal , Pancreatic Neoplasms , Humans , Fusobacterium nucleatum , Granulocyte-Macrophage Colony-Stimulating Factor , Paracrine Communication , Interleukin-8 , Pancreatic Neoplasms/pathology , Carcinoma, Pancreatic Ductal/pathology , Cell Proliferation/physiology , Pancreas , Pancreatic Neoplasms
17.
NPJ Biofilms Microbiomes ; 8(1): 87, 2022 10 29.
Article in English | MEDLINE | ID: mdl-36307484

ABSTRACT

Perturbations in the gut microbiome have been associated with colorectal cancer (CRC), with the colonic overabundance of Fusobacterium nucleatum shown as the most consistent marker. Despite its significance in the promotion of CRC, genomic studies of Fusobacterium is limited. We enrolled 43 Vietnamese CRC patients and 25 participants with non-cancerous colorectal polyps to study the colonic microbiomes and genomic diversity of Fusobacterium in this population, using a combination of 16S rRNA gene profiling, anaerobic microbiology, and whole genome analysis. Oral bacteria, including F. nucleatum and Leptotrichia, were significantly more abundant in the tumour microbiomes. We obtained 53 Fusobacterium genomes, representing 26 strains, from the saliva, tumour and non-tumour tissues of six CRC patients. Isolates from the gut belonged to diverse F. nucleatum subspecies (nucleatum, animalis, vincentii, polymorphum) and a potential new subspecies of Fusobacterium periodonticum. The Fusobacterium population within each individual was distinct and in some cases diverse, with minimal intra-clonal variation. Phylogenetic analyses showed that within four individuals, tumour-associated Fusobacterium were clonal to those isolated from non-tumour tissues. Genes encoding major virulence factors (Fap2 and RadD) showed evidence of horizontal gene transfer. Our work provides a framework to understand the genomic diversity of Fusobacterium within the CRC patients, which can be exploited for the development of CRC diagnostic and therapeutic options targeting this oncobacterium.


Subject(s)
Colorectal Neoplasms , Microbiota , Humans , RNA, Ribosomal, 16S/genetics , Phylogeny , Fusobacterium/genetics , Genomics , Colorectal Neoplasms/microbiology , Asian People
19.
Trends Cancer ; 7(3): 185-187, 2021 03.
Article in English | MEDLINE | ID: mdl-33309240

ABSTRACT

Fusobacterium nucleatum is an oral bacterium associated with colorectal cancer (CRC) proliferation, chemoresistance, inflammation, metastasis, and now DNA damage. While controlling F. nucleatum through antibiotics could reduce cancer severity, this article proposes additional strategies to block Fusobacterium-host interactions, as well as treatment of activated host immune and oncogenic signaling pathways in CRC.


Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Colorectal Neoplasms/drug therapy , Fusobacterium Infections/drug therapy , Fusobacterium nucleatum/drug effects , Host-Pathogen Interactions/drug effects , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/therapeutic use , Anti-Inflammatory Agents/pharmacology , Anti-Inflammatory Agents/therapeutic use , Antineoplastic Agents/pharmacology , Antineoplastic Agents/therapeutic use , Antineoplastic Combined Chemotherapy Protocols/pharmacology , Bacterial Proteins/antagonists & inhibitors , Bacterial Proteins/metabolism , Carcinogenesis/genetics , Carcinogenesis/immunology , Colorectal Neoplasms/genetics , Colorectal Neoplasms/immunology , Colorectal Neoplasms/microbiology , DNA Damage/drug effects , Fusobacterium Infections/genetics , Fusobacterium Infections/immunology , Fusobacterium Infections/microbiology , Fusobacterium nucleatum/pathogenicity , Host-Pathogen Interactions/genetics , Host-Pathogen Interactions/immunology , Humans , Mouth Mucosa/microbiology , Tumor Microenvironment/drug effects , Tumor Microenvironment/genetics , Tumor Microenvironment/immunology
20.
Microbiol Resour Announc ; 10(10)2021 Mar 11.
Article in English | MEDLINE | ID: mdl-33707317

ABSTRACT

Here, we report a complete genome sequence for Acinetobacter baumannii strain ATCC 17961, with plasmid sequences, and a high-quality (>98% complete) build for A. baumannii strain AB09-003. These genome sequences were generated by combining short-read Illumina and long-read Oxford Nanopore MinION sequencing data using the Unicycler hybrid assembly pipeline.

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