scholarly journals Rap-protein paralogs of B. thuringiensis: a multifunctional and redundant regulatory repertoire for the control of collective functions

2019 ◽  
Author(s):  
Gabriela Gastélum ◽  
Mayra de la Torre ◽  
Jorge Rocha
Keyword(s):  
Quorum Sensing ◽  
Proteolytic Activity ◽  
Biofilm Formation ◽  
Biological Warfare ◽  
Bacterial Populations ◽  
Regulate Gene Expression ◽  
Changing Environments ◽  
Regulatory Circuits ◽  
The Face ◽  
Protein Paralogs

AbstractQuorum Sensing (QS) are mechanisms of synthesis and detection of signaling molecules to regulate gene expression and coordinate behaviors in bacterial populations. In Bacillus subtilis (Bs), multiple paralog Rap-Phr QS systems (receptor-signaling peptide) are highly redundant and multifunctional, interconnecting the regulation of differentiation processes such as sporulation and competence. However, their functions in the B. cereus group are largely unknown. We evaluated the diversification of Rap-Phr systems in the B. cereus group as well as their functions, using Bacillus thuringiensis Bt8741 as model. Bt8741 codes for eight Rap-Phr systems; these were overexpressed to study their participation in sporulation, biofilm formation, extracellular proteolytic activity and spreading. Our results show that five Rap-Phr systems (RapC, K, F, I and RapLike) inhibit sporulation, two of which (RapK and RapF) probably dephosphorylate of Spo0F from the Spo0A phosphorelay; these two Rap proteins also inhibit biofilm formation. Five systems (RapC, F, F2, I1 and RapLike) decrease extracellular proteolytic activity; finally, four systems (RapC, F1, F2 and RapLike) participate in spreading inhibition. Our bioinformatic analyses showed that Rap proteins from the B. cereus group diversified into five pherogroups, and we foresee that functions performed by Rap proteins of Bt8741 could also be carried out by Rap homologs in other species within the group. These results indicate that Rap-Phr systems constitute a highly multifunctional and redundant regulatory repertoire that enables bacteria from the B. cereus group to efficiently regulate collective functions during the bacterial life cycle, in the face of changing environments.ImportanceThe Bacillus cereus group of bacteria includes species of high economic, clinical, biological warfare and biotechnological interest, e.g. B. anthracis in bioterrorism, B. cereus in food intoxications and B. thuringiensis in biocontrol. Knowledge on the ecology of these bacteria is hindered due to our limited understanding about the regulatory circuits that control differentiation and specialization processes. Here, we uncover the participation of eight Rap quorum-sensing receptors in collective functions of B. thuringiensis. These proteins are highly multifunctional and redundant in their functions, linking ecologically relevant processes such as sporulation, biofilm formation, extracellular proteolytic activity, spreading, and probably other additional functions in species from the B. cereus group.

scholarly journals Rap Protein Paralogs of Bacillus thuringiensis: a Multifunctional and Redundant Regulatory Repertoire for the Control of Collective Functions

2019 ◽  
Vol 202 (6) ◽  
Author(s):  
Gabriela Gastélum ◽  
Mayra de la Torre ◽  
Jorge Rocha
Keyword(s):  
Bacillus Thuringiensis ◽  
Quorum Sensing ◽  
Bacillus Cereus ◽  
Proteolytic Activity ◽  
Biofilm Formation ◽  
Bacterial Populations ◽  
Content Type ◽  
Regulatory Circuits ◽  
Signaling Peptides ◽  
The Face

ABSTRACT Quorum sensing (QS) is a mechanism of synthesis and detection of signaling molecules to regulate gene expression and coordinate behaviors in bacterial populations. In Bacillus subtilis, multiple paralog Rap-Phr QS systems (receptor-signaling peptides) are highly redundant and multifunctional, interconnecting the regulation of differentiation processes such as sporulation and competence. However, their functions in the Bacillus cereus group are largely unknown. We evaluated the functions of Rap proteins in Bacillus thuringiensis Bt8741, which codes for eight Rap-Phr systems; these were individually overexpressed to study their participation in sporulation, biofilm formation, spreading, and extracellular proteolytic activity. Our results show that four Rap-Phr systems (RapC, RapK, RapF, and RapLike) inhibit sporulation, two of which (RapK and RapF) probably dephosphorylate Spo0F from the Spo0A phosphorelay; these two Rap proteins also inhibit biofilm formation. Four systems (RapC, RacF1, RacF2, and RapLike) participate in spreading inhibition; finally, six systems (RapC, -F, -F2, -I, and -I1 and RapLike) decrease extracellular proteolytic activity. We foresee that functions performed by Rap proteins of Bt8741 could also be carried out by Rap homologs in other strains within the B. cereus group. These results indicate that Rap-Phr systems constitute a highly multifunctional and redundant regulatory repertoire that enables B. thuringiensis and other species from the B. cereus group to efficiently regulate collective functions during their life cycle in the face of changing environments. IMPORTANCE The Bacillus cereus group of bacteria includes species of high economic, clinical, biological warfare, and biotechnological interest, e.g., B. anthracis in bioterrorism, B. cereus in food intoxications, and B. thuringiensis in biocontrol. Knowledge about the ecology of these bacteria is hindered by our limited understanding of the regulatory circuits that control differentiation and specialization processes. Here, we uncover the participation of eight Rap quorum-sensing receptors in collective functions of B. thuringiensis. These proteins are highly multifunctional and redundant in their functions, linking ecologically relevant processes such as sporulation, biofilm formation, spreading, extracellular proteolytic activity, and probably other functions in species from the B. cereus group.

scholarly journals Study of quorum-sensing LasR and RhlR genes and their dependent virulence factors in Pseudomonas aeruginosa isolates from infected burn wounds

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Aya Ahmad Elnegery ◽  
Wafaa Kamel Mowafy ◽  
Tarek Ahmed Zahra ◽  
Noha Tharwat Abou El-Khier
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Proteolytic Activity ◽  
Virulence Factors ◽  
Biofilm Formation ◽  
Type Species ◽  
Assay Method ◽  
Content Type ◽  
Burn Wounds ◽  
Link Type

Background. Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen responsible for burn-wound infection. High incidence, infection severity and increasing resistance characterize P. aeruginosa -induced burn infection. Purpose. To estimate quorum-sensing (QS)-dependent virulence factors of P. aeruginosa isolates from burn wounds and correlate it to the presence of QS genes. Methods. A cross-sectional descriptive study included 50 P . aeruginosa isolates from burn patients in Mansoura University Plastic and Burn Hospital, Egypt. Antibiotic sensitivity tests were done. All isolates were tested for their ability to produce biofilm using a micro-titration assay method. Protease, pyocyanin and rhamnolipid virulence factors were determined using skimmed milk agar, King’s A medium and CTAB agar test, respectively. The identity of QS lasR and rhlR genes was confirmed using PCR. Results. In total, 86 % of isolates had proteolytic activity. Production of pyocyanin pigment was manifested in 66 % of isolates. Altogether, 76 % of isolates were rhamnolipid producers. Biofilm formation was detected in 96 % of isolates. QS lasR and rhlR genes were harboured by nearly all isolates except three isolates were negative for both lasR and rhlR genes and two isolates were positive for lasR gene and negative for rhlR gene. Forty-nine isolates were considered as extremely QS-proficient strains as they produced QS-dependent virulence factors. In contrast, one isolate was a QS deficient strain. Conclusions. QS affects P. aeruginosa virulence-factor production and biofilm in burn wounds. Isolates containing lasR and rhlR seem to be a crucial regulator of virulence factors and biofilm formation in P. aeruginosa whereas the lasR gene positively regulates biofilm formation, proteolytic activity, pyocyanin production and rhamnolipid biosurfactant synthesis. The QS regulatory RhlR gene affects protease and rhamnolipid production positively.

scholarly journals Induction of Biofilm Formation in Klebsiella pneumoniae ATCC 13884 by Several Drugs: The Possible Role of Quorum Sensing Modulation

Antibiotics ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 103 ◽  
Author(s):  
Elizabeth Cadavid ◽  
Sara Robledo ◽  
Wiston Quiñones ◽  
Fernando Echeverri
Keyword(s):  
Quorum Sensing ◽  
Klebsiella Pneumoniae ◽  
Biofilm Formation ◽  
Bacterial Resistance ◽  
Homoserine Lactone ◽  
In Vitro Assays ◽  
Bacterial Populations ◽  
Other Substances ◽  
Microplate Reader

Bacterial resistance is caused by several biochemical factors, the formation of biofilm being one of the main causes. This process is triggered by Quorum Sensing (QS), through the production of endogenous molecules, although other substances such as natural products can also do this. In this work, we aimed to determine whether some drugs are involved in the induction of biofilm formation in Klebsiella pneumoniae ATCC 13884, and thus, increase bacterial resistance. For this, the effect of 22 drugs on K. pneumoniae ATCC 13884 growth was determined at sub-plasmatic concentrations; the production of autoinducer lactones was established by HPLC and with a biosensor. The induction of biofilm formation was determined through crystal violet assay at 585 nm in a microplate reader and using urethral catheters. According to the in vitro assays, some drugs were found to induce biofilm formation in K. pneumoniae ATCC 13884. The effect of acetaminophen, hydrochlorothiazide, and progesterone stood out. The first drug caused several changes in the biochemistry of K. pneumoniae ATCC 13884 related to QS: high synthesis of N-hexanoyl-homoserine lactone, increasing bacterial populations by 27% and biofilm formation by 49%, and a more gentamicin resistant biofilm. Furthermore, it increased the colonization area of urethral catheters. Hydrochlorothiazide showed the biggest increase in the induction of biofilm formation of 51%, and progesterone displayed the greatest ability to provoke bacterial mass adherence but had no effects on K. pneumoniae ATCC 13884 bacterial population growth.

AiiA Quorum-Sensing Quenching Controls Proteolytic Activity and Biofilm Formation by Enterobacter cloacae

2012 ◽  
Vol 65 (6) ◽  
pp. 758-763 ◽  
Author(s):  
Adriana dos Reis Ponce ◽  
Maurilio Lopes Martins ◽  
Elza Fernandes de Araujo ◽  
Hilário Cuquetto Mantovani ◽  
Maria Cristina Dantas Vanetti
Keyword(s):  
Quorum Sensing ◽  
Proteolytic Activity ◽  
Biofilm Formation ◽  
Enterobacter Cloacae

scholarly journals The abaI/abaR quorum sensing system effects pathogenicity in Acinetobacter baumannii

2021 ◽  
Author(s):  
Xiaoyu Sun ◽  
Zhaohui Ni ◽  
Jie Tang ◽  
Yue Ding ◽  
Xinlei Wang ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Acinetobacter Baumannii ◽  
Biofilm Formation ◽  
Cell Communication ◽  
Regulate Gene Expression ◽  
Sensing System ◽  
Quorum Sensing System ◽  
Bacterial Quorum Sensing ◽  
Bacterial Quorum

ABSTRACTAcinetobacter baumannii is a Gram-negative pathogen that has emerged as one of the most troublesome pathogens for health care institutions globally. Bacterial quorum sensing (QS) is a process of cell-to-cell communication that relies on the production, secretion and detection of autoinducer (AI) signals to share information about cell density and regulate gene expression accordingly. In this study, we performed a comprehensive set of experiments show that deletion of quorum sensing genes showed differences in growth characteristics, morphology, biofilm formation and virulence, and increased susceptibility to some antimicrobials and exhibited motility defects. RNA-seq analysis indicated that genes involved in various aspects of energy production and conversion, Valine, leucine and isoleucine degradation and lipid transport and metabolism showed different expression.IMPORTANCEPrevious studies on bacterial quorum sensing mainly focused on biofilm formation and motility and antibiotic resistance. In this study, we focused on detecting the role of the abaI/abaR QS system in the virulence of A. baumannii. Our work provides a new insight into abaI/abaR quorum sensing system effects pathogenicity in A. baumannii. We propose that targeting the AHL synthase enzyme abaI could provide an effective strategy for attenuating virulence. On the contrary, interdicting the autoinducer synthase–receptor abaR elicits unpredictable consequences, which may lead to enhanced bacterial virulence.

Quorum Sensing – A Stratagem for Conquering Multi-Drug Resistant Pathogens

2020 ◽  
Vol 26 ◽  
Author(s):  
Madison Tonkin ◽  
Shama Khan ◽  
Mohmmad Younus Wani ◽  
Aijaz Ahmad
Keyword(s):  
Drug Resistance ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Biofilm Formation ◽  
Cell Communication ◽  
Natural Compounds ◽  
Quorum Sensing Inhibitors ◽  
Communication Technique ◽  
Multicellular Organisms ◽  
Chemical Strategies

: Quorum sensing is defined as cell to cell communication between microorganisms, which enables microorganisms to behave as multicellular organisms. Quorum sensing enables many collaborative benefits such as synchronisation of virulence factors and biofilm formation. Both quorum sensing as well as biofilm formation encourage the development of drug resistance in microorganisms. Biofilm formation and quorum sensing are causally linked to each other and play role in the pathogenesis of microorganisms. With the increasing drug resistance against the available antibiotics and antifungal medications, scientists are combining different options to develop new strategies. Such strategies rely on the inhibition of the communication and virulence factors rather than on killing or inhibiting the growth of the microorganisms. This review encompasses the communication technique used by microorganisms, how microorganism resistance is linked to quorum sensing and various chemical strategies to combat quorum sensing and thereby drug resistance. Several compounds have been identified as quorum sensing inhibitors and are known to be effective in reducing resistance as they do not kill the pathogens but rather disrupt their communication. Natural compounds have been identified as anti-quorum sensing agents. However, natural compounds present several related disadvantages. Therefore, the need for the development of synthetic or semi-synthetic compounds has arisen. This review argues that anti-quorum sensing compounds are effective in disrupting quorum sensing and could therefore be effective in reducing microorganism drug resistance.

Modulation of Gut Microbiota through Dietary Phytochemicals as a Novel Anti-infective Strategy

2020 ◽  
Vol 17 (4) ◽  
pp. 498-506 ◽  
Author(s):  
Pavan K. Mujawdiya ◽  
Suman Kapur
Keyword(s):  
Microbial Community ◽  
Quorum Sensing ◽  
Population Density ◽  
Gut Microbiota ◽  
Biofilm Formation ◽  
Chemical Interaction ◽  
Bacterial Species ◽  
Critical Role ◽  
Bacterial Cells ◽  
Gut Microbes

: Quorum Sensing (QS) is a phenomenon in which bacterial cells communicate with each other with the help of several low molecular weight compounds. QS is largely dependent on population density, and it triggers when the concentration of quorum sensing molecules accumulate in the environment and crosses a particular threshold. Once a certain population density is achieved and the concentration of molecules crosses a threshold, the bacterial cells show a collective behavior in response to various chemical stimuli referred to as “auto-inducers”. The QS signaling is crucial for several phenotypic characteristics responsible for bacterial survival such as motility, virulence, and biofilm formation. Biofilm formation is also responsible for making bacterial cells resistant to antibiotics. : The human gut is home to trillions of bacterial cells collectively called “gut microbiota” or “gut microbes”. Gut microbes are a consortium of more than 15,000 bacterial species and play a very crucial role in several body functions such as metabolism, development and maturation of the immune system, and the synthesis of several essential vitamins. Due to its critical role in shaping human survival and its modulating impact on body metabolisms, the gut microbial community has been referred to as “the forgotten organ” by O`Hara et al. (2006) [1]. Several studies have demonstrated that chemical interaction between the members of bacterial cells in the gut is responsible for shaping the overall microbial community. : Recent advances in phytochemical research have generated a lot of interest in finding new, effective, and safer alternatives to modern chemical-based medicines. In the context of antimicrobial research various plant extracts have been identified with Quorum Sensing Inhibitory (QSI) activities among bacterial cells. This review focuses on the mechanism of quorum sensing and quorum sensing inhibitors isolated from natural sources.

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