scholarly journals Mechanisms of Transforming DNA Uptake to the Periplasm of Bacillus subtilis

mBio ◽  
2021 ◽  
Author(s):  
Jeanette Hahn ◽  
Micaela DeSantis ◽  
David Dubnau
Keyword(s):  
Antibiotic Resistance ◽  
Bacillus Subtilis ◽  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Molecular Mechanism ◽  
Virulence Genes ◽  
Bacterial Species ◽  
Dna Uptake

Transformation is a widely distributed mechanism of bacterial horizontal gene transfer that plays a role in the spread of antibiotic resistance and virulence genes and more generally in evolution. Although transformation was discovered nearly a century ago and most, if not all the proteins required have been identified in several bacterial species, much remains poorly understood about the molecular mechanism of DNA uptake.

scholarly journals Mechanisms of transforming DNA uptake to the periplasm of Bacillus subtilis

2021 ◽  
Author(s):  
Jeanette Hahn ◽  
Micaela DeSantis ◽  
David Dubnau
Keyword(s):  
Bacillus Subtilis ◽  
Virulence Genes ◽  
Bacterial Species ◽  
Epifluorescence Microscopy ◽  
Cellular Distribution ◽  
Dna Uptake ◽  
Early Step ◽  
Ratchet Mechanism ◽  
New Evidence

ABSTRACTWe demonstrate here that the acquisition of DNAase resistance by transforming DNA, often assumed to indicate transport to the cytoplasm, actually reflects uptake to the periplasm, requiring a re-evaluation of conclusions about the roles of several proteins in transformation. The new evidence suggests that the transformation pilus is needed for DNA binding to the cell surface near the cell poles and for the initiation of uptake. The cellular distribution of the membrane-anchored ComEA of B. subtilis does not noticeably change during DNA uptake as does the unanchored ComEA of Vibrio and Neisseria. Instead, our evidence suggests that ComEA stabilizes the attachment of transforming DNA at localized regions in the periplasm and then mediates uptake, probably by a Brownian ratchet mechanism. Following that, the DNA is transferred to periplasmic portions of the channel protein ComEC, which plays a previously unsuspected role in uptake to the periplasm. We show that the transformation endonuclease NucA also facilitates uptake to the periplasm and that the previously demonstrated role of ComFA in the acquisition of DNAase resistance actually derives from the instability of ComGA when ComFA is deleted. These results prompt a new understanding of the early stages of DNA uptake for transformation.IMPORTANCETransformation is a widely distributed mechanism of bacterial horizontal gene transfer that plays a role in the spread of antibiotic resistance and virulence genes and more generally in evolution. Although transformation was discovered nearly a century ago and most, if not all of the proteins required have been identified in several bacterial species, much remains poorly understood about the molecular mechanism of DNA uptake. This study uses epifluorescence microscopy to investigate the passage of labeled DNA into the compartment between the cell wall and the cell membrane of Bacillus subtilis, a necessary early step in transformation. The roles of individual proteins in this process are identified, and their modes of action are clarified.

scholarly journals A Conserved Metal Binding Motif in the Bacillus subtilis Competence Protein ComFA Enhances Transformation

2017 ◽  
Vol 199 (15) ◽  
Author(s):  
Scott S. Chilton ◽  
Tanya G. Falbel ◽  
Susan Hromada ◽  
Briana M. Burton
Keyword(s):  
Bacillus Subtilis ◽  
Amino Acid ◽  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Metal Binding ◽  
Dna Uptake ◽  
Content Type ◽  
Efficient Transformation ◽  
Dead Box ◽  
The Dead

ABSTRACT Genetic competence is a process in which cells are able to take up DNA from their environment, resulting in horizontal gene transfer, a major mechanism for generating diversity in bacteria. Many bacteria carry homologs of the central DNA uptake machinery that has been well characterized in Bacillus subtilis. It has been postulated that the B. subtilis competence helicase ComFA belongs to the DEAD box family of helicases/translocases. Here, we made a series of mutants to analyze conserved amino acid motifs in several regions of B. subtilis ComFA. First, we confirmed that ComFA activity requires amino acid residues conserved among the DEAD box helicases, and second, we show that a zinc finger-like motif consisting of four cysteines is required for efficient transformation. Each cysteine in the motif is important, and mutation of at least two of the cysteines dramatically reduces transformation efficiency. Further, combining multiple cysteine mutations with the helicase mutations shows an additive phenotype. Our results suggest that the helicase and metal binding functions are two distinct activities important for ComFA function during transformation. IMPORTANCE ComFA is a highly conserved protein that has a role in DNA uptake during natural competence, a mechanism for horizontal gene transfer observed in many bacteria. Investigation of the details of the DNA uptake mechanism is important for understanding the ways in which bacteria gain new traits from their environment, such as drug resistance. To dissect the role of ComFA in the DNA uptake machinery, we introduced point mutations into several motifs in the protein sequence. We demonstrate that several amino acid motifs conserved among ComFA proteins are important for efficient transformation. This report is the first to demonstrate the functional requirement of an amino-terminal cysteine motif in ComFA.

scholarly journals Biofilm Formation Drives Transfer of the Conjugative Element ICEBs1inBacillus subtilis

mSphere ◽  
2018 ◽  
Vol 3 (5) ◽  
Author(s):  
Frédéric Lécuyer ◽  
Jean-Sébastien Bourassa ◽  
Martin Gélinas ◽  
Vincent Charron-Lamoureux ◽  
Vincent Burrus ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Antibiotic Resistance ◽  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Biofilm Formation ◽  
Bacterial Species ◽  
High Rate ◽  
Conjugative Transfer ◽  
Bacterial Strains ◽  
Content Type

ABSTRACTHorizontal gene transfer by integrative and conjugative elements (ICEs) is a very important mechanism for spreading antibiotic resistance in various bacterial species. In environmental and clinical settings, most bacteria form biofilms as a way to protect themselves against extracellular stress. However, much remains to be known about ICE transfer in biofilms. Using ICEBs1fromBacillus subtilis, we show that the natural conjugation efficiency of this ICE is greatly affected by the ability of the donor and recipient to form a biofilm. ICEBs1transfer considerably increases in biofilm, even at low donor/recipient ratios. Also, while there is a clear temporal correlation between biofilm formation and ICEBs1transfer, biofilms do not alter the level of ICEBs1excision in donor cells. Conjugative transfer appears to be favored by the biophysical context of biofilms. Indeed, extracellular matrix production, particularly from the recipient cells, is essential for biofilms to promote ICEBs1transfer. Our study provides basic new knowledge on the high rate of conjugative transfer of ICEs in biofilms, a widely preponderant bacterial lifestyle in the environment, which could have a major impact on our understanding of horizontal gene transfer in natural and clinical environments.IMPORTANCETransfer of mobile genetic elements from one bacterium to another is the principal cause of the spread of antibiotic resistance. However, the dissemination of these elements in environmental contexts is poorly understood. In clinical and environmental settings, bacteria are often found living in multicellular communities encased in a matrix, a structure known as a biofilm. In this study, we examined how forming a biofilm influences the transmission of an integrative and conjugative element (ICE). Using the model Gram-positive bacteriumB. subtilis, we observed that biofilm formation highly favors ICE transfer. This increase in conjugative transfer is due to the production of extracellular matrix, which creates an ideal biophysical context. Our study provides important insights into the role of the biofilm structure in driving conjugative transfer, which is of major importance since biofilm is a widely preponderant bacterial lifestyle for clinically relevant bacterial strains.

scholarly journals Kin discrimination promotes horizontal gene transfer between unrelated strains in Bacillus subtilis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Polonca Stefanic ◽  
Katarina Belcijan ◽  
Barbara Kraigher ◽  
Rok Kostanjšek ◽  
Joseph Nesme ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Social Interactions ◽  
Recipient Strain ◽  
Donor Strain ◽  
Kin Discrimination ◽  
Defence Mechanisms ◽  
Donor Cells ◽  
Novel Alleles

AbstractBacillus subtilis is a soil bacterium that is competent for natural transformation. Genetically distinct B. subtilis swarms form a boundary upon encounter, resulting in killing of one of the strains. This process is mediated by a fast-evolving kin discrimination (KD) system consisting of cellular attack and defence mechanisms. Here, we show that these swarm antagonisms promote transformation-mediated horizontal gene transfer between strains of low relatedness. Gene transfer between interacting non-kin strains is largely unidirectional, from killed cells of the donor strain to surviving cells of the recipient strain. It is associated with activation of a stress response mediated by sigma factor SigW in the donor cells, and induction of competence in the recipient strain. More closely related strains, which in theory would experience more efficient recombination due to increased sequence homology, do not upregulate transformation upon encounter. This result indicates that social interactions can override mechanistic barriers to horizontal gene transfer. We hypothesize that KD-mediated competence in response to the encounter of distinct neighbouring strains could maximize the probability of efficient incorporation of novel alleles and genes that have proved to function in a genomically and ecologically similar context.

scholarly journals An Evolutionary Link between Natural Transformation and CRISPR Adaptive Immunity

mBio ◽  
2012 ◽  
Vol 3 (5) ◽  
Author(s):  
Peter Jorth ◽  
Marvin Whiteley
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Bacterial Diversity ◽  
Natural Transformation ◽  
Bacterial Species ◽  
Comparative Genomic ◽  
Content Type ◽  
Immune Systems ◽  
Adaptive Immune ◽  
Adaptive Immune Systems

ABSTRACTNatural transformation by competent bacteria is a primary means of horizontal gene transfer; however, evidence that competence drives bacterial diversity and evolution has remained elusive. To test this theory, we used a retrospective comparative genomic approach to analyze the evolutionary history ofAggregatibacter actinomycetemcomitans, a bacterial species with both competent and noncompetent sister strains. Through comparative genomic analyses, we reveal that competence is evolutionarily linked to genomic diversity and speciation. Competence loss occurs frequently during evolution and is followed by the loss of clustered regularly interspaced short palindromic repeats (CRISPRs), bacterial adaptive immune systems that protect against parasitic DNA. Relative to noncompetent strains, competent bacteria have larger genomes containing multiple rearrangements. In contrast, noncompetent bacterial genomes are extremely stable but paradoxically susceptible to infective DNA elements, which contribute to noncompetent strain genetic diversity. Moreover, incomplete noncompetent strain CRISPR immune systems are enriched for self-targeting elements, which suggests that the CRISPRs have been co-opted for bacterial gene regulation, similar to eukaryotic microRNAs derived from the antiviral RNA interference pathway.IMPORTANCEThe human microbiome is rich with thousands of diverse bacterial species. One mechanism driving this diversity is horizontal gene transfer by natural transformation, whereby naturally competent bacteria take up environmental DNA and incorporate new genes into their genomes. Competence is theorized to accelerate evolution; however, attempts to test this theory have proved difficult. Through genetic analyses of the human periodontal pathogenAggregatibacter actinomycetemcomitans, we have discovered an evolutionary connection between competence systems promoting gene acquisition and CRISPRs (clustered regularly interspaced short palindromic repeats), adaptive immune systems that protect bacteria against genetic parasites. We show that competentA. actinomycetemcomitansstrains have numerous redundant CRISPR immune systems, while noncompetent bacteria have lost their CRISPR immune systems because of inactivating mutations. Together, the evolutionary data linking the evolution of competence and CRISPRs reveals unique mechanisms promoting genetic heterogeneity and the rise of new bacterial species, providing insight into complex mechanisms underlying bacterial diversity in the human body.

scholarly journals Acquisition of Beta-Lactamase by Neisseria meningitidis through Possible Horizontal Gene Transfer

2018 ◽  
Vol 62 (9) ◽  
Author(s):  
Eva Hong ◽  
Ala-Eddine Deghmane ◽  
Muhamed-Kheir Taha
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Genome Sequencing ◽  
Meningococcal Disease ◽  
Bacterial Species ◽  
Whole Genome ◽  
Beta Lactamase ◽  
Content Type ◽  
Beta Lactamases ◽  
Lactamase Gene

ABSTRACT We report the detection in France of a beta-lactamase-producing invasive meningococcal isolate. Whole-genome sequencing of the isolate revealed a ROB-1-type beta-lactamase gene that is frequently encountered in Haemophilus influenzae, suggesting horizontal transfer between isolates of these bacterial species. Beta-lactamases are exceptional in meningococci, with no reports for more than 2 decades. This report is worrying, as the expansion of such isolates may jeopardize the effective treatment against invasive meningococcal disease.

scholarly journals Horizontally transferred genes in the ctenophore Mnemiopsis leidyi encode enzymes and are expressed during early development

2017 ◽  
Author(s):  
Alexandra M Hernandez ◽  
Joseph F Ryan
Keyword(s):  
Antibiotic Resistance ◽  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Early Development ◽  
Genetic Information ◽  
Mnemiopsis Leidyi ◽  
Uncharacterized Protein ◽  
Phylogenetic Incongruence ◽  
Wide Range ◽  
Growing Body

Horizontal gene transfer has had major impacts on the biology of a wide range of organisms from antibiotic resistance in bacteria to adaptations to herbivory in arthropods. A growing body of literature shows that horizontal gene transfer (HGT) between non-animals and animals is more commonplace than previously thought. In this study, we present a thorough investigation of HGT in the ctenophore Mnemiopsis leidyi. We applied tests of phylogenetic incongruence to identify nine genes that were likely transferred horizontally early in ctenophore evolution from bacteria and non-metazoan eukaryotes. All but one of these HGTs (an uncharacterized protein) appear to perform enzymatic activities in M. leidyi, supporting previous observations that enzymes are more likely to be retained after HGT events. We found that the majority of these nine horizontally transferred genes were expressed during early development, suggesting that they are active and play a role in the biology of M. leidyi. This is the first report of HGT in ctenophores, and contributes to an ever-growing literature on the prevalence of genetic information flowing between non-animals and animals.

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