Identification of a Fifth Antibacterial Toxin Produced by a Single Bacteroides fragilis Strain

Shumaker, Andrew M.; McEneany, Valentina Laclare; Coyne, Michael J.; Silver, Pamela A.; Comstock, Laurie E.

doi:10.1128/jb.00577-18

Cited by 22 publications

(16 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…41 Bfr strains either possess the bsap-1 gene encoding the toxin, or they lack the gene and are sensitive to it. 42 Producers of BSAP-1 have a gene adjacent to the bsap-1 gene that encodes an orthologue of the target outer membrane protein that serves as the receptor for BSAP-1 in the target bacterium. 43 This orthologue is structurally similar to the target receptor but is sufficiently different, so as not to be targeted by the toxin, but to protect the producer from it.…”

Section: Antimicrobial Toxins Are Used In Bacterial Competitionmentioning

confidence: 99%

Gut Bacteroides species in health and disease

2021

View full text Add to dashboard Cite

The functional diversity of the mammalian intestinal microbiome far exceeds that of the host organism, and microbial genes contribute substantially to the well-being of the host. However, beneficial gut organisms can also be pathogenic when present in the gut or other locations in the body. Among dominant beneficial bacteria are several species of Bacteroides, which metabolize polysaccharides and oligosaccharides, providing nutrition and vitamins to the host and other intestinal microbial residents. These topics and the specific organismal and molecular interactions that are known to be responsible for the beneficial and detrimental effects of Bacteroides species in humans comprise the focus of this review. The complexity of these interactions will be revealed.

show abstract

Section: Antimicrobial Toxins Are Used In Bacterial Competitionmentioning

confidence: 99%

Gut Bacteroides species in health and disease

2021

View full text Add to dashboard Cite

show abstract

“…A small inhibition zone was observed, corresponding to the size of the original bacterial spot, demonstrating that Bf 9343 produces an additional antimicrobial toxin, as is typical of B. fragilis strains (59, 60). These analyses show that pLGB30 allows for easy creation of double-crossover mutants in erythromycin-resistant strains where tetracycline selection of cointegrates is necessary.…”

Section: Resultsmentioning

confidence: 95%

“…Analyses of recent human fecal isolates of Bacteroidales with interesting phenotypes revealed that many are resistant to both tetracycline and erythromycin (60, 65) and therefore are not amenable to genetic manipulation using available genetic tools for these bacteria. We evaluated tetracycline and erythromycin resistance among 120 Bacteroides strains from our collection isolated between 2009 and 2011 from the stool of 15 healthy U.S.-resident adults with no history of gastrointestinal diseases (Fig.…”

Section: Resultsmentioning

confidence: 99%

Streamlined Genetic Manipulation of Diverse Bacteroides and Parabacteroides Isolates from the Human Gut Microbiota

García-Bayona

Comstock

2019

mBio

Self Cite

107

View full text Add to dashboard Cite

Studies of the gut microbiota have dramatically increased in recent years as the importance of this microbial ecosystem to human health and disease is better appreciated. The Bacteroidales are the most abundant order of bacteria in the healthy human gut and induce both health-promoting and disease-promoting effects. There are more than 55 species of gut Bacteroidales with extensive intraspecies genetic diversity, especially in regions involved in the synthesis of molecules that interact with other bacteria, the host, and the diet. This property necessitates the study of diverse species and strains. In recent years, the genetic toolkit to study these bacteria has greatly expanded, but we still lack a facile system for creating deletion mutants and allelic replacements in diverse strains, especially with the rapid increase in resistance to the two antibiotics used for genetic manipulation. Here, we present a new versatile and highly efficient vector suite that allows the creation of allelic deletions and replacements in multiresistant strains of Bacteroides and Parabacteroides using a gain-of-function system based on polysaccharide utilization. These vectors also allow for easy counterselection independent of creating a mutant background strain, using a toxin from a type VI secretion system of Bacteroides fragilis. Toxin production during counterselection is induced with one of two different molecules, providing flexibility based on strain phenotypes. This family of vectors greatly facilitates functional genetic analyses and extends the range of gut Bacteroidales strains that can be genetically modified to include multiresistant strains that are currently genetically intractable with existing genetic tools. IMPORTANCE We have entered an era when studies of the gut microbiota are transitioning from basic questions of composition and host effects to understanding the microbial molecules that underlie compositional shifts and mediate health and disease processes. The importance of the gut Bacteroidales to human health and disease and their potential as a source of engineered live biotherapeutics make these bacteria of particular interest for in-depth mechanistic study. However, there are still barriers to the genetic analysis of diverse Bacteroidales strains, limiting our ability to study important host and community phenotypes identified in these strains. Here, we have overcome many of these obstacles by constructing a series of vectors that allow easy genetic manipulation in diverse gut Bacteroides and Parabacteroides strains. These constructs fill a critical need and allow streamlined allelic replacement in diverse gut Bacteroidales, including the growing number of multiantibiotic-resistant strains present in the modern-day human intestine.

show abstract

“…The cholesterol-dependent cytolysin (CDCs) are a family of β-barrel pore-forming toxins expressed by many Gram-positive pathogens, but only identified in a few Gram-negative terrestrial bacteria to date ( 1 ). The CDCs share a domain 3 (D3) protein fold with many evolutionarily distant proteins, including members of the mammalian membrane attack complex/perforin family (MACPF) ( 2 – 7 ). This structural domain is characterized by a core β-sheet flanked by two contiguous α-helical bundles (αHBs) ( Fig.…”

Section: Introductionmentioning

confidence: 99%

“…fold with many evolutionarily distant proteins, including members of the mammalian membrane attack complex/perforin family (MACPF) (2)(3)(4)(5)(6)(7). This structural domain is characterized by a core ␤-sheet flanked by two contiguous ␣-helical bundles (␣HBs) (Fig.…”

mentioning

confidence: 99%

A Key Motif in the Cholesterol-Dependent Cytolysins Reveals a Large Family of Related Proteins

Evans

Johnstone

Lawrence

et al. 2020

mBio

View full text Add to dashboard Cite

The cholesterol-dependent cytolysins (CDCs) are bacterial, β-barrel, pore-forming toxins. A central enigma of the pore-forming mechanism is how completion of the prepore is sensed to initiate its conversion to the pore. We identified a motif that is conserved between the CDCs and a diverse family of nearly 300 uncharacterized proteins present in over 220 species that span at least 10 bacterial and 2 eukaryotic phyla. Except for this motif, these proteins exhibit little similarity to the CDCs at the primary structure level. Studies herein show this motif is a critical component of the sensor that initiates the prepore-to-pore transition in the CDCs. We further show by crystallography, single particle analysis, and biochemical studies of one of these CDC-like (CDCL) proteins from Elizabethkingia anophelis, a commensal of the malarial mosquito midgut, that a high degree of structural similarity exists between the CDC and CDCL monomer structures and both form large oligomeric pore complexes. Furthermore, the conserved motif in the E. anophelis CDCL crystal structure occupies a nearly identical position and makes similar contacts to those observed in the structure of the archetype CDC, perfringolysin O (PFO). This suggests a common function in the CDCs and CDCLs and may explain why only this motif is conserved in the CDCLs. Hence, these studies identify a critical component of the sensor involved in initiating the prepore-to-pore transition in the CDCs, which is conserved in a large and diverse group of distant relatives of the CDCs. IMPORTANCE The cholesterol-dependent cytolysins’ pore-forming mechanism relies on the ability to sense the completion of the oligomeric prepore structure and initiate the insertion of the β-barrel pore from the assembled prepore structure. These studies show that a conserved motif is an important component of the sensor that triggers the prepore-to-pore transition and that it is conserved in a large family of previously unidentified CDC-like proteins, the genes for which are present in a vast array of microbial species that span most terrestrial environments, as well as most animal and human microbiomes. These studies establish the foundation for future investigations that will probe the contribution of this large family of CDC-like proteins to microbial survival and human disease.

show abstract

Identification of a Fifth Antibacterial Toxin Produced by a Single Bacteroides fragilis Strain

Cited by 22 publications

References 19 publications

Gut Bacteroides species in health and disease

Gut Bacteroides species in health and disease

Streamlined Genetic Manipulation of Diverse Bacteroides and Parabacteroides Isolates from the Human Gut Microbiota

A Key Motif in the Cholesterol-Dependent Cytolysins Reveals a Large Family of Related Proteins

Contact Info

Product

Resources

About