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  1. Article ; Online: Reciprocal regulation of enterococcal cephalosporin resistance by products of the autoregulated yvcJ-glmR-yvcL operon enhances fitness during cephalosporin exposure.

    Djorić, Dušanka / Atkinson, Samantha N / Kristich, Christopher J

    PLoS genetics

    2024  Volume 20, Issue 3, Page(s) e1011215

    Abstract: Enterococci are commensal members of the gastrointestinal tract and also major nosocomial pathogens. They possess both intrinsic and acquired resistance to many antibiotics, including intrinsic resistance to cephalosporins that target bacterial cell wall ...

    Abstract Enterococci are commensal members of the gastrointestinal tract and also major nosocomial pathogens. They possess both intrinsic and acquired resistance to many antibiotics, including intrinsic resistance to cephalosporins that target bacterial cell wall synthesis. These antimicrobial resistance traits make enterococcal infections challenging to treat. Moreover, prior therapy with antibiotics, including broad-spectrum cephalosporins, promotes enterococcal proliferation in the gut, resulting in dissemination to other sites of the body and subsequent infection. As a result, a better understanding of mechanisms of cephalosporin resistance is needed to enable development of new therapies to treat or prevent enterococcal infections. We previously reported that flow of metabolites through the peptidoglycan biosynthesis pathway is one determinant of enterococcal cephalosporin resistance. One factor that has been implicated in regulating flow of metabolites into cell wall biosynthesis pathways of other Gram-positive bacteria is GlmR. In enterococci, GlmR is encoded as the middle gene of a predicted 3-gene operon along with YvcJ and YvcL, whose functions are poorly understood. Here we use genetics and biochemistry to investigate the function of the enterococcal yvcJ-glmR-yvcL gene cluster. Our results reveal that YvcL is a DNA-binding protein that regulates expression of the yvcJ-glmR-yvcL operon in response to cell wall stress. YvcJ and GlmR bind UDP-GlcNAc and reciprocally regulate cephalosporin resistance in E. faecalis, and binding of UDP-GlcNAc by YvcJ appears essential for its activity. Reciprocal regulation by YvcJ/GlmR is essential for fitness during exposure to cephalosporin stress. Additionally, our results indicate that enterococcal GlmR likely acts by a different mechanism than the previously studied GlmR of Bacillus subtilis, suggesting that the YvcJ/GlmR regulatory module has evolved unique targets in different species of bacteria.
    MeSH term(s) Cephalosporins/pharmacology ; Cephalosporins/metabolism ; Cephalosporin Resistance/genetics ; Anti-Bacterial Agents/pharmacology ; Enterococcus faecalis/genetics ; Operon/genetics ; Uridine Diphosphate/metabolism
    Chemical Substances Cephalosporins ; Anti-Bacterial Agents ; Uridine Diphosphate (58-98-0)
    Language English
    Publishing date 2024-03-21
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2186725-2
    ISSN 1553-7404 ; 1553-7390
    ISSN (online) 1553-7404
    ISSN 1553-7390
    DOI 10.1371/journal.pgen.1011215
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: PASTA-kinase-mediated signaling drives accumulation of the peptidoglycan synthesis protein MurAA to promote cephalosporin resistance in Enterococcus faecalis.

    Mascari, Carly A / Little, Jaime L / Kristich, Christopher J

    Molecular microbiology

    2023  Volume 120, Issue 6, Page(s) 811–829

    Abstract: The bacterial PASTA kinase, IreK, is required for intrinsic cephalosporin resistance in the Gram-positive opportunistic pathogen, Enterococcus faecalis. IreK activity is enhanced in response to cell wall stress, such as cephalosporin exposure. The ... ...

    Abstract The bacterial PASTA kinase, IreK, is required for intrinsic cephalosporin resistance in the Gram-positive opportunistic pathogen, Enterococcus faecalis. IreK activity is enhanced in response to cell wall stress, such as cephalosporin exposure. The downstream consequences of IreK activation are not well understood in E. faecalis, but recent work in other low-GC Gram-positive bacteria demonstrated PASTA kinase-dependent regulation of MurAA, an enzyme that performs the first committed step in the peptidoglycan synthesis pathway. Here, we used genetic suppressor selections to identify MurAA as a downstream target of IreK signaling in E. faecalis. Using complementary genetic and biochemical approaches, we demonstrated that MurAA abundance is regulated by IreK signaling in response to physiologically relevant cell wall stress to modulate substrate flux through the peptidoglycan synthesis pathway. Specifically, the IreK substrate, IreB, promotes proteolysis of MurAA through a direct physical interaction in a manner responsive to phosphorylation by IreK. MurAB, a homolog of MurAA, also promotes MurAA proteolysis and interacts directly with IreB. Our results therefore establish a connection between the cell wall stress sensor IreK and one critical physiological output to modulate peptidoglycan synthesis and drive cephalosporin resistance.
    MeSH term(s) Enterococcus faecalis/metabolism ; Peptidoglycan/metabolism ; Cephalosporin Resistance/genetics ; Bacterial Proteins/genetics ; Bacterial Proteins/metabolism ; Phosphotransferases/metabolism ; Cell Wall/metabolism
    Chemical Substances Peptidoglycan ; Bacterial Proteins ; Phosphotransferases (EC 2.7.-)
    Language English
    Publishing date 2023-09-08
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 619315-8
    ISSN 1365-2958 ; 0950-382X
    ISSN (online) 1365-2958
    ISSN 0950-382X
    DOI 10.1111/mmi.15150
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  3. Article ; Online: CCR2-dependent CX3CR1+ colonic macrophages promote

    Jennings, Kevin C / Johnson, Kaitlin E / Hayward, Michael A / Kristich, Christopher J / Salzman, Nita H

    Infection and immunity

    2024  , Page(s) e0000624

    Abstract: Enterococci are common commensal bacteria that colonize the gastrointestinal tracts of most mammals, including humans. Importantly, these bacteria are one of the leading causes of nosocomial infections. This study examined the role of colonic macrophages ...

    Abstract Enterococci are common commensal bacteria that colonize the gastrointestinal tracts of most mammals, including humans. Importantly, these bacteria are one of the leading causes of nosocomial infections. This study examined the role of colonic macrophages in facilitating
    Language English
    Publishing date 2024-04-17
    Publishing country United States
    Document type Journal Article
    ZDB-ID 218698-6
    ISSN 1098-5522 ; 0019-9567
    ISSN (online) 1098-5522
    ISSN 0019-9567
    DOI 10.1128/iai.00006-24
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Conformational changes in the activation loop of a bacterial PASTA kinase.

    Bluma, Matthew S / Schultz, Kathryn M / Kristich, Christopher J / Klug, Candice S

    Protein science : a publication of the Protein Society

    2023  Volume 32, Issue 7, Page(s) e4697

    Abstract: Many bacterial genomes encode a transmembrane protein kinase belonging to the PASTA kinase family, which controls numerous processes in diverse bacterial pathogens, including antibiotic resistance, cell division, stress resistance, toxin production, and ... ...

    Abstract Many bacterial genomes encode a transmembrane protein kinase belonging to the PASTA kinase family, which controls numerous processes in diverse bacterial pathogens, including antibiotic resistance, cell division, stress resistance, toxin production, and virulence. PASTA kinases share a conserved three-part domain architecture, consisting of an extracellular PASTA domain, proposed to sense the peptidoglycan layer status, a single transmembrane helix, and an intracellular Ser/Thr kinase domain. The crystal structures of the kinase domain from two homologous PASTA kinases reveal a characteristic two-lobed structure typical of eukaryotic protein kinases with a centrally located, but unresolved, activation loop that becomes phosphorylated and regulates downstream signaling pathways. We previously identified three sites of phosphorylation on the activation loop (T163, T166, and T168) of IreK, a PASTA kinase from the pathogen Enterococcus faecalis, as well as a distal phosphorylation site (T218) that each influence IreK activity in vivo. Still, the mechanism by which loop phosphorylation regulates PASTA kinase function is yet unknown. Therefore, we utilized site-directed spin labeling (SDSL) and continuous wave (CW) electron paramagnetic resonance (EPR) spectroscopy to assess the E. faecalis IreK kinase activation loop dynamics, including the effects of phosphorylation on activation loop motion, and the IreK-IreB interaction. Our results reveal that the IreK activation loop occupies a more immobile state when dephosphorylated, and that loop autophosphorylation shifts the loop to a more mobile state that can then enable interaction with IreB, a known substrate.
    MeSH term(s) Protein Serine-Threonine Kinases/metabolism ; Phosphorylation ; Signal Transduction ; Protein Kinases/metabolism ; Bacteria/metabolism
    Chemical Substances Protein Serine-Threonine Kinases (EC 2.7.11.1) ; Protein Kinases (EC 2.7.-)
    Language English
    Publishing date 2023-06-13
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 1106283-6
    ISSN 1469-896X ; 0961-8368
    ISSN (online) 1469-896X
    ISSN 0961-8368
    DOI 10.1002/pro.4697
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: GpsB Promotes PASTA Kinase Signaling and Cephalosporin Resistance in

    Minton, Nicole E / Djorić, Dušanka / Little, Jaime / Kristich, Christopher J

    Journal of bacteriology

    2022  Volume 204, Issue 10, Page(s) e0030422

    Abstract: Enterococci are opportunistic pathogens that can cause severe bacterial infections. Treatment of these infections is challenging because enterococci possess intrinsic and acquired mechanisms of resistance to commonly used antibiotics, including ... ...

    Abstract Enterococci are opportunistic pathogens that can cause severe bacterial infections. Treatment of these infections is challenging because enterococci possess intrinsic and acquired mechanisms of resistance to commonly used antibiotics, including cephalosporins. The transmembrane serine/threonine PASTA kinase, IreK, is an important determinant of enterococcal cephalosporin resistance. Upon exposure to cephalosporins, IreK becomes autophosphorylated, which stimulates its kinase activity to phosphorylate downstream substrates and drive cephalosporin resistance. However, the molecular mechanisms that modulate IreK autophosphorylation in response to cell wall stress, such as that induced by cephalosporins, remain unknown. A cytoplasmic protein, GpsB, promotes signaling by PASTA kinase homologs in other bacterial species, but the function of enterococcal GpsB has not been previously investigated. We used
    MeSH term(s) Enterococcus faecalis/metabolism ; Cephalosporin Resistance ; Cephalosporins/pharmacology ; Cephalosporins/metabolism ; Phosphotransferases/metabolism ; Signal Transduction ; Protein Serine-Threonine Kinases/genetics ; Anti-Bacterial Agents/pharmacology ; Anti-Bacterial Agents/metabolism ; Threonine/metabolism ; Threonine/pharmacology ; Serine/metabolism
    Chemical Substances Cephalosporins ; Phosphotransferases (EC 2.7.-) ; Protein Serine-Threonine Kinases (EC 2.7.11.1) ; Anti-Bacterial Agents ; Threonine (2ZD004190S) ; Serine (452VLY9402)
    Language English
    Publishing date 2022-09-12
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2968-3
    ISSN 1098-5530 ; 0021-9193
    ISSN (online) 1098-5530
    ISSN 0021-9193
    DOI 10.1128/jb.00304-22
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Use of an Interspecies Chimeric Receptor for Inducible Gene Expression Reveals that Metabolic Flux through the Peptidoglycan Biosynthesis Pathway is an Important Driver of Cephalosporin Resistance in Enterococcus faecalis.

    Mascari, Carly A / Djorić, Dušanka / Little, Jaime L / Kristich, Christopher J

    Journal of bacteriology

    2022  Volume 204, Issue 4, Page(s) e0060221

    Abstract: Cephalosporins are commonly prescribed antibiotics that impair cross-linking of the bacterial cell wall. The Gram-positive opportunistic pathogen, Enterococcus faecalis, is intrinsically resistant to these antibiotics and proliferates substantially ... ...

    Abstract Cephalosporins are commonly prescribed antibiotics that impair cross-linking of the bacterial cell wall. The Gram-positive opportunistic pathogen, Enterococcus faecalis, is intrinsically resistant to these antibiotics and proliferates substantially during cephalosporin therapy. As a result, the usage of cephalosporins has the potential to lead to life-threatening enterococcal infections. Yet, the molecular mechanisms that drive cephalosporin resistance (CR) are incompletely understood. Previously, we demonstrated that MurAA, an enzyme that catalyzes the first committed step in peptidoglycan (PG) synthesis, is required for CR. However, the mechanism by which MurAA contributes to CR remained unknown. Here, we tested the hypothesis that MurAA drives CR by controlling metabolic flux through the PG synthesis pathway. To do so, we developed and exploited an inducible gene expression system for E. faecalis based on an interspecies chimeric receptor that responds to exogenous nitrate for control of expression from a NisR-regulated promoter (P
    MeSH term(s) Anti-Bacterial Agents/metabolism ; Anti-Bacterial Agents/pharmacology ; Cephalosporin Resistance/genetics ; Cephalosporins/metabolism ; Cephalosporins/pharmacology ; Enterococcus faecalis/metabolism ; Gene Expression ; Peptidoglycan/metabolism
    Chemical Substances Anti-Bacterial Agents ; Cephalosporins ; Peptidoglycan
    Language English
    Publishing date 2022-03-08
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2968-3
    ISSN 1098-5530 ; 0021-9193
    ISSN (online) 1098-5530
    ISSN 0021-9193
    DOI 10.1128/jb.00602-21
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  7. Article ; Online: Multisite Phosphorylation Regulates GpsB Function in Cephalosporin Resistance of Enterococcus faecalis.

    VanZeeland, Nicole E / Schultz, Kathryn M / Klug, Candice S / Kristich, Christopher J

    Journal of molecular biology

    2023  Volume 435, Issue 18, Page(s) 168216

    Abstract: Enterococci are normal human commensals and major causes of hospital-acquired infections. Enterococcal infections can be difficult to treat because enterococci harbor intrinsic and acquired antibiotic resistance, such as resistance to cephalosporins. In ... ...

    Abstract Enterococci are normal human commensals and major causes of hospital-acquired infections. Enterococcal infections can be difficult to treat because enterococci harbor intrinsic and acquired antibiotic resistance, such as resistance to cephalosporins. In Enterococcus faecalis, the transmembrane kinase IreK, a member of the bacterial PASTA kinase family, is essential for cephalosporin resistance. The activity of IreK is boosted by the cytoplasmic protein GpsB, which promotes IreK autophosphorylation and signaling to drive cephalosporin resistance. A previous phosphoproteomics study identified eight putative IreK-dependent phosphorylation sites on GpsB, but the functional importance of GpsB phosphorylation was unknown. Here we used genetic and biochemical approaches to define three sites of phosphorylation on GpsB that functionally impact IreK activity and cephalosporin resistance. Phosphorylation at two sites (S80 and T84) serves to impair the ability of GpsB to activate IreK in vivo, suggesting phosphorylation of these sites acts as a means of negative feedback for IreK. The third site of phosphorylation (T133) occurs in a segment of GpsB termed the C-terminal extension that is unique to enterococcal GpsB homologs. The C-terminal extension is highly mobile in solution, suggesting it is largely unstructured, and phosphorylation of T133 appears to enable efficient phosphorylation at S80 / T84. Overall our results are consistent with a model in which multisite phosphorylation of GpsB impairs its ability to activate IreK, thereby diminishing signal transduction through the IreK-dependent pathway and modulating phenotypic cephalosporin resistance.
    MeSH term(s) Humans ; Anti-Bacterial Agents/pharmacology ; Bacterial Proteins/genetics ; Bacterial Proteins/metabolism ; Cephalosporin Resistance/genetics ; Enterococcus faecalis/drug effects ; Enterococcus faecalis/genetics ; Phosphorylation ; Protein Serine-Threonine Kinases/metabolism ; Signal Transduction/genetics ; Cephalosporins/pharmacology
    Chemical Substances Anti-Bacterial Agents ; Bacterial Proteins ; Protein Serine-Threonine Kinases (EC 2.7.11.1) ; Cephalosporins
    Language English
    Publishing date 2023-07-28
    Publishing country Netherlands
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 80229-3
    ISSN 1089-8638 ; 0022-2836
    ISSN (online) 1089-8638
    ISSN 0022-2836
    DOI 10.1016/j.jmb.2023.168216
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  8. Article ; Online: Convergence of PASTA Kinase and Two-Component Signaling in Response to Cell Wall Stress in Enterococcus faecalis.

    Kellogg, Stephanie L / Kristich, Christopher J

    Journal of bacteriology

    2018  Volume 200, Issue 12

    Abstract: Two common signal transduction mechanisms used by bacteria to sense and respond to changing environments are two-component systems (TCSs) and eukaryote-like Ser/Thr kinases and phosphatases (eSTK/Ps). ...

    Abstract Two common signal transduction mechanisms used by bacteria to sense and respond to changing environments are two-component systems (TCSs) and eukaryote-like Ser/Thr kinases and phosphatases (eSTK/Ps).
    MeSH term(s) Anti-Bacterial Agents/pharmacology ; Bacterial Proteins/genetics ; Bacterial Proteins/metabolism ; Cell Wall/drug effects ; Cell Wall/enzymology ; Cell Wall/genetics ; Cell Wall/metabolism ; Enterococcus faecalis/drug effects ; Enterococcus faecalis/enzymology ; Enterococcus faecalis/genetics ; Enterococcus faecalis/metabolism ; Gene Expression Regulation, Bacterial/drug effects ; Histidine Kinase/genetics ; Histidine Kinase/metabolism ; Phosphorylation ; Signal Transduction/drug effects
    Chemical Substances Anti-Bacterial Agents ; Bacterial Proteins ; Histidine Kinase (EC 2.7.13.1)
    Language English
    Publishing date 2018-05-24
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2968-3
    ISSN 1098-5530 ; 0021-9193
    ISSN (online) 1098-5530
    ISSN 0021-9193
    DOI 10.1128/JB.00086-18
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  9. Article ; Online: Multiple Low-Reactivity Class B Penicillin-Binding Proteins Are Required for Cephalosporin Resistance in Enterococci.

    Djorić, Dušanka / Little, Jaime L / Kristich, Christopher J

    Antimicrobial agents and chemotherapy

    2020  Volume 64, Issue 4

    Abstract: Enterococcus ... ...

    Abstract Enterococcus faecalis
    MeSH term(s) Acylation ; Cephalosporin Resistance/physiology ; Cross Infection/drug therapy ; Cross Infection/microbiology ; Electrophoresis, Polyacrylamide Gel ; Enterococcus faecalis/drug effects ; Enterococcus faecalis/metabolism ; Enterococcus faecium/drug effects ; Enterococcus faecium/metabolism ; Gastrointestinal Tract/microbiology ; Humans ; Immunoblotting ; Inhibitory Concentration 50 ; Microscopy, Electron, Transmission ; Penicillin-Binding Proteins/chemistry ; Penicillin-Binding Proteins/metabolism ; Penicillin-Binding Proteins/physiology ; Peptidoglycan/biosynthesis
    Chemical Substances Penicillin-Binding Proteins ; Peptidoglycan
    Language English
    Publishing date 2020-03-24
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 217602-6
    ISSN 1098-6596 ; 0066-4804
    ISSN (online) 1098-6596
    ISSN 0066-4804
    DOI 10.1128/AAC.02273-19
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  10. Article ; Online: The enterococcal PASTA kinase: A sentinel for cell envelope stress.

    Djorić, Dušanka / Minton, Nicole E / Kristich, Christopher J

    Molecular oral microbiology

    2020  Volume 36, Issue 2, Page(s) 132–144

    Abstract: Enterococci are Gram-positive, opportunistic pathogens that reside throughout the gastrointestinal tracts of most terrestrial organisms. Enterococci are resistant to many antibiotics, which makes enterococcal infections difficult to treat. Enterococci ... ...

    Abstract Enterococci are Gram-positive, opportunistic pathogens that reside throughout the gastrointestinal tracts of most terrestrial organisms. Enterococci are resistant to many antibiotics, which makes enterococcal infections difficult to treat. Enterococci are also particularly hardy bacteria that can tolerate a variety of environmental stressors. Understanding how enterococci sense and respond to the extracellular environment to enact adaptive biological responses may identify new targets that can be exploited for development of treatments for enterococcal infections. Bacterial eukaryotic-like serine/threonine kinases (eSTKs) and cognate phosphatases (STPs) are important signaling systems that mediate biological responses to extracellular stimuli. Some bacterial eSTKs are transmembrane proteins that contain a series of extracellular repeats of the penicillin-binding and Ser/Thr kinase-associated (PASTA) domain, leading to their designation as "PASTA kinases." Enterococcal genomes encode a single PASTA kinase and its cognate phosphatase. Investigations of the enterococcal PASTA kinase revealed its importance in resistance to antibiotics and other cell wall stresses, in enterococcal colonization of the mammalian gut, clues about its mechanism of signal transduction, and its integration with other enterococcal signal transduction systems. In this review, we describe the current state of knowledge of PASTA kinase signaling in enterococci and describe important gaps that still need to be addressed to provide a better understanding of this important signaling system.
    MeSH term(s) Animals ; Anti-Bacterial Agents/pharmacology ; Cell Membrane/metabolism ; Cell Wall/metabolism ; Enterococcus faecalis ; Protein Serine-Threonine Kinases/genetics ; Protein Serine-Threonine Kinases/metabolism ; Protein Serine-Threonine Kinases/pharmacology ; Signal Transduction
    Chemical Substances Anti-Bacterial Agents ; Protein Serine-Threonine Kinases (EC 2.7.11.1)
    Language English
    Publishing date 2020-10-05
    Publishing country Denmark
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Review
    ZDB-ID 2537726-7
    ISSN 2041-1014 ; 2041-1006
    ISSN (online) 2041-1014
    ISSN 2041-1006
    DOI 10.1111/omi.12313
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