scholarly journals The conserved serine transporter SdaC moonlights to enable self recognition

2021 ◽  
Author(s):  
Achala Chittor ◽  
Karine A. Gibbs
Keyword(s):  
Escherichia Coli ◽  
Protein Evolution ◽  
Sequence Variation ◽  
Bacterial Survival ◽  
Ecological Constraints ◽  
Collective Behaviors ◽  
Open Conformation ◽  
Self Recognition ◽  
Recognition Protein ◽  
Cooperative Behaviors

AbstractCells can use self recognition to achieve cooperative behaviors. Self-recognition genes principally evolve in tandem with partner self-recognition alleles. However, other constraints on protein evolution could exist. Here, we have identified an interaction outside of self-recognition loci that could constrain the sequence variation of a self-recognition protein. We show that during collective swarm expansion in Proteus mirabilis, self-recognition signaling co-opts SdaC, a serine transporter. Serine uptake is crucial for bacterial survival and colonization. Single-residue variants of SdaC reveal that self recognition requires an open conformation of the protein; serine transport is dispensable. A distant ortholog from Escherichia coli is sufficient for self recognition; however, a homologous serine transporter, YhaO, is not. Thus, SdaC couples self recognition and serine transport, likely through a shared molecular interface. Understanding molecular and ecological constraints on self-recognition proteins can provide insights into the evolution of self recognition and emergent collective behaviors.Abstract Figure

scholarly journals The conserved serine transporter SdaC moonlights to enable self recognition

2021 ◽  
Author(s):  
Achala Chittor ◽  
Karine A. Gibbs
Keyword(s):  
Proteus Mirabilis ◽  
Sequence Variation ◽  
Interaction Network ◽  
Bacterial Survival ◽  
Ecological Constraints ◽  
Collective Behaviors ◽  
Open Conformation ◽  
Self Recognition ◽  
Recognition Protein ◽  
Recognition Systems

Cells can use self recognition to achieve cooperative behaviors. Self-recognition genes are thought to principally evolve in tandem with partner self-recognition alleles. However, other constraints on protein evolution could exist. Here, we have identified an interaction outside of self-recognition loci that could constrain the sequence variation of a self-recognition protein. We show that during collective swarm expansion in Proteus mirabilis , self-recognition signaling co-opts SdaC, a serine transporter. Serine uptake is crucial for bacterial survival and colonization. Single-residue variants of SdaC reveal that self recognition requires an open conformation of the protein; serine transport is dispensable. A distant ortholog from Escherichia coli is sufficient for self recognition; however, a paralogous serine transporter, YhaO, is not. Thus, SdaC couples self recognition and serine transport, likely through a shared molecular interface. Self recognition proteins may follow the framework of a complex interaction network rather than an isolated two-protein system. Understanding molecular and ecological constraints on self-recognition proteins lays the groundwork for insights into the evolution of self recognition and emergent collective behaviors. Importance Bacteria can receive secret messages from kin during migration. For Proteus mirabilis , these messages are necessary for virulence in multi-species infections. We show that a serine transporter—conserved among gamma-enterobacteria– enables self recognition. Molecular co-option of nutrient uptake could limit the sequence variation of these message proteins. SdaC is the primary transporter for L-serine, a vital metabolite for colonization during disease. Unlike many self-recognition receptors, SdaC is sufficiently conserved between species to achieve recognition. The predicted open conformation is shared by transport and recognition. SdaC reveals the interdependence of communication and nutrient acquisition. As the broader interactions of self-recognition proteins are studied, features shared among microbial self-recognition systems, such as Dictyostelium spp. and Neurospora spp., could emerge.

scholarly journals SdiA Aids Enterohemorrhagic Escherichia coli Carriage by Cattle Fed a Forage or Grain Diet

2013 ◽  
Vol 81 (9) ◽  
pp. 3472-3478 ◽  
Author(s):  
Haiqing Sheng ◽  
Y. N. Nguyen ◽  
Carolyn J. Hovde ◽  
Vanessa Sperandio
Keyword(s):  
Escherichia Coli ◽  
Type Strain ◽  
Deletion Mutant ◽  
Wild Type Strain ◽  
Rumen Fluid ◽  
Acid Resistance ◽  
Enterohemorrhagic Escherichia Coli ◽  
Dependent Manner ◽  
Bacterial Survival ◽  
Wild Type

ABSTRACTEnterohemorrhagicEscherichia coli(EHEC) causes hemorrhagic colitis and life-threatening complications. The main reservoirs for EHEC are healthy ruminants. We reported that SdiA senses acyl homoserine lactones (AHLs) in the bovine rumen to activate expression of the glutamate acid resistance (gad) genes priming EHEC's acid resistance before they pass into the acidic abomasum. Conversely, SdiA represses expression of the locus of enterocyte effacement (LEE) genes, whose expression is not required for bacterial survival in the rumen but is necessary for efficient colonization at the rectoanal junction (RAJ) mucosa. Our previous studies show that SdiA-dependent regulation was necessary for efficient EHEC colonization of cattle fed a grain diet. Here, we compared the SdiA role in EHEC colonization of cattle fed a forage hay diet. We detected AHLs in the rumen of cattle fed a hay diet, and these AHLs activatedgadgene expression in an SdiA-dependent manner. The rumen fluid and fecal samples from hay-fed cattle were near neutrality, while the same digesta samples from grain-fed animals were acidic. Cattle fed either grain or hay and challenged with EHEC orally carried the bacteria similarly. EHEC was cleared from the rumen within days and from the RAJ mucosa after approximately one month. In competition trials, where animals were challenged with both wild-type and SdiA deletion mutant bacteria, diet did not affect the outcome that the wild-type strain was better able to persist and colonize. However, the wild-type strain had a greater advantage over the SdiA deletion mutant at the RAJ mucosa among cattle fed the grain diet.

scholarly journals Structural insights into the mechanism of c-di-GMP–bound YcgR regulating flagellar motility in Escherichia coli

2019 ◽  
Vol 295 (3) ◽  
pp. 808-821 ◽  
Author(s):  
Yan-Jie Hou ◽  
Wen-Si Yang ◽  
Yuan Hong ◽  
Ying Zhang ◽  
Da-Cheng Wang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Motor Proteins ◽  
Flagellar Motor ◽  
Bacterial Survival ◽  
Flagellar Motility ◽  
Surface Attachment ◽  
Bacterial Surface ◽  
Motility Regulation ◽  
Survival And Growth ◽  
Structural Insights

The motile-sessile transition is critical for bacterial survival and growth. Cyclic-di-GMP (c-di-GMP) plays a central role in controlling this transition and regulating biofilm formation via various effectors. As an effector of c-di-GMP in Escherichia coli and related species, the PilZ domain–containing protein YcgR responds to elevated c-di-GMP concentrations and acts on the flagellar motor to suppress bacterial motility in a brakelike fashion, which promotes bacterial surface attachment. To date, several target proteins within the motor, MotA, FliG, and FliM, along with different regulatory mechanisms have been reported. However, how YcgR acts on these components remains unclear. Here, we report that activated YcgR stably binds to MotA at the MotA-FliG interface and thereby regulates bacterial swimming. Biochemical and structural analyses revealed that c-di-GMP rearranges the PilZ domain configuration, resulting in the formation of a MotA-binding patch consisting of an RXXXR motif and the C-tail helix α3. Moreover, we noted that a conserved region in the YcgR-N domain, which is independent of MotA interaction, is necessary for motility regulation. On the basis of these findings, we infer that the YcgR-N domain is required for activity on other motor proteins. We propose that activated YcgR appends to MotA via its PilZ domain and thereby interrupts the MotA-FliG interaction and simultaneously interacts with other motor proteins via its YcgR-N domain to inhibit flagellar motility. Our findings suggest that the mode of interaction between YcgR and motor proteins may be shared by other PilZ family proteins.

scholarly journals Occurrence and ecological determinants of the contamination of floodplain wetlands with Klebsiella pneumoniae and pathogenic or antibiotic-resistant Escherichia coli.

2019 ◽  
Vol 95 (8) ◽  
Author(s):  
Charles P Henriot ◽  
Daniel Martak ◽  
Quentin Cuenot ◽  
Christophe Loup ◽  
Hélène Masclaux ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Resistant Bacteria ◽  
Bacterial Survival ◽  
Floodplain Wetlands ◽  
Antibiotic Resistant ◽  
E Coli ◽  
Physico Chemical ◽  
Chemical Conditions ◽  
One Year ◽  
Three Rivers

ABSTRACT The survival and multiplication of human pathogenic and antibiotic-resistant bacteria in ecosystems is of increasing concern but has been little explored. Wetlands can be contaminated by water fluxes from rivers and may present environmental conditions leading to bacterial survival and multiplication. To test this hypothesis, we sampled 16 wetlands located along three rivers of the Jura Massif, France. The bacterial contamination of the wetland and river waters was measured monthly over a one-year cycle together with the water physico-chemical characteristics. We assessed the abundance of three pathogenic species: Escherichia coli,Klebsiella pneumoniaeand Pseudomonas aeruginosa. The concentrations of E. coli producing extended-spectrum β-lactamase (ESBL E. coli) or belonging to the phylogenetic group B2 (E. coli B2–more pathogenic) were also measured. We found that rivers carried total E. coli, ESBL E. coli, and K. pneumoniae to wetlands. ESBL E. coli poorly survived in wetlands, whereas total E. coli and K. pneumoniae possibly met favourable physico-chemical conditions for survival and multiplication in these habitats. K. pneumoniae peaked in summer in warm and shallow wetlands. Total E. coli and E. coli B2 potentially reached wetlands through sources other than rivers (hillslope groundwater or leaching from contaminated fields).

scholarly journals rhs Genes Are Potential Markers for Multilocus Sequence Typing of Escherichia coli O157:H7 Strains

2009 ◽  
Vol 75 (18) ◽  
pp. 5853-5862 ◽  
Author(s):  
K. Liu ◽  
S. J. Knabel ◽  
E. G. Dudley
Keyword(s):  
Escherichia Coli ◽  
Phylogenetic Analysis ◽  
Multilocus Sequence Typing ◽  
Sequence Variation ◽  
Escherichia Coli O157 ◽  
Positive Selection Pressure ◽  
E Coli ◽  
The Past ◽  
Unique Markers ◽  
Sequence Types

ABSTRACT DNA sequence-based molecular subtyping methods such as multilocus sequence typing (MLST) are commonly used to generate phylogenetic inferences for monomorphic pathogens. The development of an effective MLST scheme for subtyping Escherichia coli O157:H7 has been hindered in the past due to the lack of sequence variation found within analyzed housekeeping and virulence genes. A recent study suggested that rhs genes are under strong positive selection pressure, and therefore in this study we analyzed these genes within a diverse collection of E. coli O157:H7 strains for sequence variability. Eighteen O157:H7 strains from lineages I and II and 15 O157:H7 strains from eight clades were included. Examination of these rhs genes revealed 44 polymorphic loci (PL) and 10 sequence types (STs) among the 18 lineage strains and 280 PL and 12 STs among the 15 clade strains. Phylogenetic analysis using rhs genes generally grouped strains according to their known lineage and clade classifications. These findings also suggested that O157:H7 strains from clades 6 and 8 fall into lineage I/II and that strains of clades 1, 2, 3, and 4 fall into lineage I. Additionally, unique markers were found in rhsA and rhsJ that might be used to define clade 8 and clade 6. Therefore, rhs genes may be useful markers for phylogenetic analysis of E. coli O157:H7.

Peptide nucleic acid restores colistin susceptibility through modulation of MCR-1 expression in Escherichia coli

2020 ◽  
Author(s):  
Xiaoming Wang ◽  
Yao Wang ◽  
Zhuoren Ling ◽  
Chaoyang Zhang ◽  
Mingming Fu ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Peptide Nucleic Acid ◽  
Promoter Activity ◽  
Sequence Variation ◽  
Promoter Sequence ◽  
E Coli ◽  
Expression In Escherichia Coli ◽  
Expression Host ◽  
Antisense Approach ◽  
Increased Susceptibility

Abstract Background Plasmid-mediated mechanisms of drug resistance accelerate the spread of polymyxin resistance, leaving clinicians with few or no antibacterial options for the treatment of infections caused by MDR bacteria, especially carbapenemase-producing strains. Objectives To evaluate the associations among promoter sequence variation, mcr-1 expression, host factors and levels of colistin resistance and to propose antisense agents such as peptide nucleic acids (PNAs) targeting mcr-1 as a tool to restore colistin susceptibility through modulation of MCR-1 expression in Escherichia coli. Methods A β-galactosidase assay was performed to study mcr-1 promoter activity. Quantitative real-time PCR and western blot assays were used to identify the expression level of MCR-1 in WT strains and transformants. Three PNAs targeting different regions of mcr-1 were designed and synthesized to determine whether they can effectively inhibit MCR-1 expression. MIC was measured to test colistin susceptibility in the presence or absence of PNA-1 in mcr-1-carrying E. coli. Results Variation in the mcr-1 promoter sequence and host species affect promoter activity, MCR-1 expression levels and colistin MICs. One PNA targeting the ribosome-binding site fully inhibited the expression of mcr-1 at a concentration of 4 μM, resulting in significantly increased susceptibility to colistin. The MIC90 of colistin decreased from 8 to 2 mg/L (P < 0.05) in the presence of 4 μM PNA. Conclusions These findings suggest that the antisense approach is a possible strategy to combat mcr-1-mediated resistance as well as other causes of emerging global resistance.

scholarly journals TmPGRP-SA regulates Antimicrobial Response to Bacteria and Fungi in the Fat Body and Gut of Tenebrio molitor

2020 ◽  
Vol 21 (6) ◽  
pp. 2113 ◽  
Author(s):  
Maryam Keshavarz ◽  
Yong Hun Jo ◽  
Tariku Tesfaye Edosa ◽  
Young Min Bae ◽  
Yeon Soo Han
Keyword(s):  
Escherichia Coli ◽  
Fat Body ◽  
Mrna Level ◽  
Tenebrio Molitor ◽  
Mortality Rates ◽  
E Coli ◽  
Peptidoglycan Recognition Protein ◽  
Recognition Protein ◽  
Bacteria And Fungi ◽  
Antimicrobial Immune Response

Antimicrobial immune response is mediated by a signal-transducing sensor, peptidoglycan recognition protein-SA (PGRP-SA), that can recognize non-self molecules. Although several studies have focused on the involvement of Drosophila PGRP-SA in antimicrobial peptide (AMP) expression in response to infections, studies on its role in Tenebrio molitor are lacking. Here, we present a functional analysis of T. molitor PGRP-SA (TmPGRP-SA). In the absence of microbes, TmPGRP-SA was highly expressed in the late-larval fat body, followed by hemocytes, and gut. Interestingly, following Escherichia coli, Staphylococcus aureus, and Candida albicans infections, the mRNA level of TmPGRP-SA was significantly upregulated in both the fat body and gut. TmPGRP-SA silencing had a significant effect on the mortality rates for all the microbes tested. Moreover, TmPGRP-SA is required for regulating the expression of eight AMP genes namely TmTenecin-1, -2, and -4; TmDefensin-1 and -2; TmColeoptericin-1; and TmAttacin-1b and -2 in the fat body in response to E. coli and S. aureus infections. TmPGRP-SA is essential for the transcription of TmTenecin-2, -4; TmDefensin-2; TmColeoptericin-1, -2; and TmAttacin-1a, -1b, and -2 in the gut upon E. coli and C. albicans infections. However, TmPGRP-SA does not regulate AMP expression in the hemocytes. Additionally, TmDorsal isoform X2, a downstream Toll transcription factor, was downregulated in TmPGRP-SA-silenced larval fat body following E. coli and S. aureus challenges, and in the gut following E. coli and C. albicans challenges.

scholarly journals mcr-1 Gene Expression Modulates the Inflammatory Response of Human Macrophages to Escherichia coli

2020 ◽  
Vol 88 (8) ◽  
Author(s):  
Giorgio Mattiuz ◽  
Sabrina Nicolò ◽  
Alberto Antonelli ◽  
Tommaso Giani ◽  
Ilaria Baccani ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Lipid A ◽  
Nuclear Translocation ◽  
Interleukin 12 ◽  
Bacterial Survival ◽  
Necrosis Factor Alpha ◽  
Content Type ◽  
Human Macrophages ◽  
E Coli ◽  
The Impact

ABSTRACT MCR-1 is a plasmid-encoded phosphoethanolamine transferase able to modify the lipid A structure. It confers resistance to colistin and was isolated from human, animal, and environmental strains of Enterobacteriaceae, raising serious global health concerns. In this paper, we used recombinant mcr-1-expressing Escherichia coli to study the impact of MCR-1 products on E. coli-induced activation of inflammatory pathways in activated THP-1 cells, which was used as a model of human macrophages. We found that infection with recombinant mcr-1-expressing E. coli significantly modulated p38-MAPK and Jun N-terminal protein kinase (JNK) activation and pNF-κB nuclear translocation as well as the expression of genes for the relevant proinflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin-12 (IL-12), and IL-1β compared with mcr-1-negative strains. Caspase-1 activity and IL-1β secretion were significantly less activated by mcr-1-positive E. coli strains than the mcr-1-negative parental strain. Similar results were obtained with clinical isolates of mcr-1-positive E. coli, suggesting that, in addition to colistin resistance, the expression of mcr-1 allows the escape of early host innate defenses and may promote bacterial survival.

Survival of Escherichia coli in agricultural soil and presence in tile drainage and shallow groundwater

2010 ◽  
Vol 90 (3) ◽  
pp. 495-505 ◽  
Author(s):  
A C VanderZaag ◽  
K J Campbell ◽  
R C Jamieson ◽  
A C Sinclair ◽  
L G Hynes
Keyword(s):  
Escherichia Coli ◽  
Fecal Contamination ◽  
Shallow Groundwater ◽  
Drainage Water ◽  
Tile Drainage ◽  
Subsurface Water ◽  
Bacterial Survival ◽  
Manure Application ◽  
Monitoring Wells ◽  
E Coli

Animal agriculture and the use of manure as a soil amendment can lead to enteric pathogens entering water used for drinking, irrigation, and recreation. The presence of Escherichia coli in water is commonly used as an indicator of recent fecal contamination; however, a few recent studies suggest some E. coli populations are able to survive for extended time periods in agricultural soils. This important finding needs to be further assessed with field-scale studies. To this end, we conducted a 1-yr study within a 9.6-ha field that had received fertilizer and semi-solid dairy cattle manure annually for the past decade. Escherichia coli concentrations were monitored throughout the year (before and after manure application) in the effluent from tile drains (at approximately 80 cm depth) and in 5- to 8-m-deep groundwater wells. Escherichia coli was detected in both groundwater and tile drain effluent at concentrations exceeding irrigation and recreational water-quality guidelines. Within two of the monitoring wells, concentrations of E. coli, and frequency of detections, were greatest several months after the manure application. In two monitoring wells and one tile drain the frequency of E. coli detections was higher before manure was applied than after. This suggests the presence and abundance of E. coli was not strongly related to the timing of manure application. A laboratory study using naladixic acid resistant E. coli showed the bacteria could survive at least two times longer in soil samples collected from the study field than in soil from the adjacent riparian area, which had not received manure applications. Together, field and lab results suggest that a consistent source of E. coli exists within the field, which may include “naturalized” strains of E. coli. Further studies are required to determine the specific source of E. coli detected in tile drainage water and shallow groundwater. If the E. coli recovered in subsurface water is primarily mobilized from naturalized populations residing within the soil profile, this indicator organism would have little value as an indicator of recent fecal contamination. Key words: Bacterial survival, naturalized Escherichia coli, groundwater, tile drainage

scholarly journals Nickel Promotes Biofilm Formation by Escherichia coli K-12 Strains That Produce Curli

2009 ◽  
Vol 75 (6) ◽  
pp. 1723-1733 ◽  
Author(s):  
Claire Perrin ◽  
Romain Briandet ◽  
Gregory Jubelin ◽  
Philippe Lejeune ◽  
Marie-Andrée Mandrand-Berthelot ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
Molecular Mechanisms ◽  
Selective Advantage ◽  
Bacterial Survival ◽  
Toxic Compounds ◽  
E Coli ◽  
Transcriptional Effect ◽  
K 12 ◽  
Encoding Genes

ABSTRACT The survival of bacteria exposed to toxic compounds is a multifactorial phenomenon, involving well-known molecular mechanisms of resistance but also less-well-understood mechanisms of tolerance that need to be clarified. In particular, the contribution of biofilm formation to survival in the presence of toxic compounds, such as nickel, was investigated in this study. We found that a subinhibitory concentration of nickel leads Escherichia coli bacteria to change their lifestyle, developing biofilm structures rather than growing as free-floating cells. Interestingly, whereas nickel and magnesium both alter the global cell surface charge, only nickel promotes biofilm formation in our system. Genetic evidence indicates that biofilm formation induced by nickel is mediated by the transcriptional induction of the adhesive curli-encoding genes. Biofilm formation induced by nickel does not rely on efflux mechanisms using the RcnA pump, as these require a higher concentration of nickel to be activated. Our results demonstrate that the nickel-induced biofilm formation in E. coli is an adaptational process, occurring through a transcriptional effect on genes coding for adherence structures. The biofilm lifestyle is obviously a selective advantage in the presence of nickel, but the means by which it improves bacterial survival needs to be investigated.

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