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2.
EBioMedicine ; 90: 104524, 2023 Apr.
Article in English | MEDLINE | ID: mdl-36958992

ABSTRACT

BACKGROUND: Post-treatment Lyme disease syndrome (PTLDS) is used to describe Lyme disease patients who have the infection cleared by antibiotic but then experienced persisting symptoms of pain, fatigue, or cognitive impairment. Currently, little is known about the cause or epidemiology of PTLDS. METHODS: We conducted a data-driven study with a large nationwide administrative dataset, which consists of more than 98 billion billing and 1.4 billion prescription records between 2008 and 2016, to identify unique aspects of PTLDS that could have diagnostic and etiologic values. We defined PTLDS based on its symptomatology and compared the demographic, longitudinal changes of comorbidity, and antibiotic prescriptions between patients who have Lyme with absence of prolonged symptoms (APS) and PTLDS. FINDINGS: The age and temporal distributions were similar between Lyme APS and PTLDS. The PTLDS-to-Lyme APS case ratio was 3.42%. The co-occurrence of 3 out of 19 chronic conditions were significantly higher in PTLDS versus Lyme APS-odds ratio and 95% CI for anemia, hyperlipidemia, and osteoarthrosis were 1.46 (1.11-1.92), 1.39 (1.15-1.68), and 1.62 (1.23-2.12) respectively. We did not find significant differences between PTLDS and Lyme APS for the number of types of antibiotics prescribed (incidence rate ratio = 1.009, p = 0.90) and for the prescription of each of the five antibiotics (FDR adjusted p values 0.72-0.95). INTERPRETATION: PTLDS cases have more codes corresponding to anemia, hyperlipidemia, and osteoarthrosis compared to Lyme APS. Our finding of hyperlipidemia is consistent with a dysregulation of fat metabolism reported by other researchers, and further investigation should be conducted to understand the potential biological relationship between the two. FUNDING: Steven & Alexandra Cohen Foundation, Global Lyme Alliance, and the Pazala Foundation; National Institutes of Health R01ES032470.


Subject(s)
Lyme Disease , Post-Lyme Disease Syndrome , Humans , Post-Lyme Disease Syndrome/complications , Post-Lyme Disease Syndrome/drug therapy , Lyme Disease/diagnosis , Lyme Disease/drug therapy , Lyme Disease/epidemiology , Anti-Bacterial Agents/therapeutic use , Chronic Disease , Pain/drug therapy
3.
Angew Chem Int Ed Engl ; 61(32): e202206183, 2022 08 08.
Article in English | MEDLINE | ID: mdl-35704446

ABSTRACT

A modular total synthesis of kibdelomycin is disclosed that should enable structure-activity relationship (SAR) studies of this interesting class of antibiotics. The route uses simple building blocks and addresses lingering questions about its structural assignment and relationship to amycolamicin, a recently described natural product reported to have a similar structure. Initial antibacterial assays reveal that both C-22 epimers (the N-glycosidic linkage) of the natural product have similar activity while structurally truncated analogs lose activity.


Subject(s)
Biological Products , Pyrrolidinones , Anti-Bacterial Agents/chemistry , Pyrroles , Pyrrolidinones/chemistry , Structure-Activity Relationship
4.
Skeletal Radiol ; 51(1): 161-169, 2022 Jan.
Article in English | MEDLINE | ID: mdl-34136939

ABSTRACT

OBJECTIVE: A local anesthetic is frequently administered as part of a lumbar epidural steroid injection (LESI); however, there is a rare potential for this to result in transient paralysis if administered incorrectly. The purpose of this retrospective study is to determine if the addition of bupivacaine significantly improves patient-reported pain scores. MATERIALS AND METHODS: This retrospective review includes patients undergoing LESI over an approximately 1 year time span. Pre-procedure, immediate post-procedure, and 1-week integer scaled pain scores were recorded. Ordinal regression was used to compare the distributions of the aggregated ordinal pain score categories between bupivacaine- and non-bupivacaine-injected patients. RESULTS: Two hundred fifty-eight patients met the inclusion criteria (126F:132 M, mean age 64.7 years) with 164 receiving bupivacaine and steroids and 94 receiving steroids alone. The relative frequency distributions for pre-injection pain did not differ between the bupivacaine patients and the non-bupivacaine patients (p = 0.114). Similarly, the relative frequency distributions for immediate and 1-week post-procedure pain did not differ between the bupivacaine patients and the non-bupivacaine patients (p = 0.293 at immediate time point and p = 0.306 at 1-week time point). Odds ratios comparing pain severity change between the bupivacaine and non-bupivacaine patients also were not significantly different at either the immediate post-procedure (p = 0.769) or 1-week (p = 0.203) time points. CONCLUSION: The lack of a significant downward shift in the bupivacaine patients' post-procedure pain scores compared to the non-bupivacaine patients' post-procedure pain scores raises doubts about bupivacaine's utility as a standard component of a lumbar epidural injection.


Subject(s)
Bupivacaine , Steroids , Anesthetics, Local , Humans , Injections, Epidural , Middle Aged , Pain , Retrospective Studies , Treatment Outcome
5.
Cell ; 184(21): 5405-5418.e16, 2021 10 14.
Article in English | MEDLINE | ID: mdl-34619078

ABSTRACT

Lyme disease is on the rise. Caused by a spirochete Borreliella burgdorferi, it affects an estimated 500,000 people in the United States alone. The antibiotics currently used to treat Lyme disease are broad spectrum, damage the microbiome, and select for resistance in non-target bacteria. We therefore sought to identify a compound acting selectively against B. burgdorferi. A screen of soil micro-organisms revealed a compound highly selective against spirochetes, including B. burgdorferi. Unexpectedly, this compound was determined to be hygromycin A, a known antimicrobial produced by Streptomyces hygroscopicus. Hygromycin A targets the ribosomes and is taken up by B. burgdorferi, explaining its selectivity. Hygromycin A cleared the B. burgdorferi infection in mice, including animals that ingested the compound in a bait, and was less disruptive to the fecal microbiome than clinically relevant antibiotics. This selective antibiotic holds the promise of providing a better therapeutic for Lyme disease and eradicating it in the environment.


Subject(s)
Anti-Bacterial Agents/therapeutic use , Lyme Disease/drug therapy , Animals , Borrelia burgdorferi/drug effects , Calibration , Cinnamates/chemistry , Cinnamates/pharmacology , Cinnamates/therapeutic use , Drug Evaluation, Preclinical , Feces/microbiology , Female , HEK293 Cells , Hep G2 Cells , Humans , Hygromycin B/analogs & derivatives , Hygromycin B/chemistry , Hygromycin B/pharmacology , Hygromycin B/therapeutic use , Lyme Disease/microbiology , Mice , Microbial Sensitivity Tests , Microbiota/drug effects
6.
Microbiome ; 9(1): 92, 2021 04 14.
Article in English | MEDLINE | ID: mdl-33853672

ABSTRACT

BACKGROUND: Infectious bacterial diseases exhibiting increasing resistance to antibiotics are a serious global health issue. Bacteriophage therapy is an anti-microbial alternative to treat patients with serious bacterial infections. However, the impacts to the host microbiome in response to clinical use of phage therapy are not well understood. RESULTS: Our paper demonstrates a largely unchanged microbiota profile during 4 weeks of phage therapy when added to systemic antibiotics in a single patient with Staphylococcus aureus device infection. Metabolomic analyses suggest potential indirect cascading ecological impacts to the host (skin) microbiome. We did not detect genomes of the three phages used to treat the patient in metagenomic samples taken from saliva, stool, and skin; however, phages were detected using endpoint-PCR in patient serum. CONCLUSION: Results from our proof-of-principal study supports the use of bacteriophages as a microbiome-sparing approach to treat bacterial infections. Video abstract.


Subject(s)
Bacteriophages , Microbiota , Phage Therapy , Staphylococcal Infections , Anti-Bacterial Agents/therapeutic use , Bacteriophages/genetics , Humans , Staphylococcal Infections/drug therapy
7.
mBio ; 11(5)2020 09 29.
Article in English | MEDLINE | ID: mdl-32994327

ABSTRACT

Lyme disease is the most common vector-borne disease in the United States, with an estimated incidence of 300,000 infections annually. Antibiotic intervention cures Lyme disease in the majority of cases; however, 10 to 20% of patients develop posttreatment Lyme disease syndrome (PTLDS), a debilitating condition characterized by chronic fatigue, pain, and cognitive difficulties. The underlying mechanism responsible for PTLDS symptoms, as well as a reliable diagnostic tool, has remained elusive. We reasoned that the gut microbiome may play an important role in PTLDS given that the symptoms overlap considerably with conditions in which a dysbiotic microbiome has been observed, including mood, cognition, and autoimmune disorders. Analysis of sequencing data from a rigorously curated cohort of patients with PTLDS revealed a gut microbiome signature distinct from that of healthy control subjects, as well as from that of intensive care unit (ICU) patients. Notably, microbiome sequencing data alone were indicative of PTLDS, which presents a potential, novel diagnostic tool for PTLDS.IMPORTANCE Most patients with acute Lyme disease are cured with antibiotic intervention, but 10 to 20% endure debilitating symptoms such as fatigue, neurological complications, and myalgias after treatment, a condition known as posttreatment Lyme disease syndrome (PTLDS). The etiology of PTLDS is not understood, and objective diagnostic tools are lacking. PTLDS symptoms overlap several diseases in which patients exhibit alterations in their microbiome. We found that patients with PTLDS have a distinct microbiome signature, allowing for an accurate classification of over 80% of analyzed cases. The signature is characterized by an increase in Blautia, a decrease in Bacteroides, and other changes. Importantly, this signature supports the validity of PTLDS and is the first potential biological diagnostic tool for the disease.


Subject(s)
Anti-Bacterial Agents/therapeutic use , Dysbiosis/etiology , Lyme Disease/drug therapy , Microbiota/drug effects , Post-Lyme Disease Syndrome/microbiology , Adult , Bacteria/classification , Bacteria/genetics , Bacteria/isolation & purification , Cohort Studies , Feces/microbiology , Female , Humans , Male , Middle Aged , Post-Lyme Disease Syndrome/diagnosis , Transcriptome
9.
Nature ; 576(7787): 459-464, 2019 12.
Article in English | MEDLINE | ID: mdl-31747680

ABSTRACT

The current need for novel antibiotics is especially acute for drug-resistant Gram-negative pathogens1,2. These microorganisms have a highly restrictive permeability barrier, which limits the penetration of most compounds3,4. As a result, the last class of antibiotics that acted against Gram-negative bacteria was developed in the 1960s2. We reason that useful compounds can be found in bacteria that share similar requirements for antibiotics with humans, and focus on Photorhabdus symbionts of entomopathogenic nematode microbiomes. Here we report a new antibiotic that we name darobactin, which was obtained using a screen of Photorhabdus isolates. Darobactin is coded by a silent operon with little production under laboratory conditions, and is ribosomally synthesized. Darobactin has an unusual structure with two fused rings that form post-translationally. The compound is active against important Gram-negative pathogens both in vitro and in animal models of infection. Mutants that are resistant to darobactin map to BamA, an essential chaperone and translocator that folds outer membrane proteins. Our study suggests that bacterial symbionts of animals contain antibiotics that are particularly suitable for development into therapeutics.


Subject(s)
Anti-Bacterial Agents/isolation & purification , Anti-Bacterial Agents/pharmacology , Gram-Negative Bacteria/drug effects , Gram-Negative Bacteria/pathogenicity , Phenylpropionates/isolation & purification , Phenylpropionates/pharmacology , Animals , Anti-Bacterial Agents/chemistry , Bacterial Outer Membrane Proteins/antagonists & inhibitors , Bacterial Outer Membrane Proteins/chemistry , Bacterial Outer Membrane Proteins/genetics , Bacterial Outer Membrane Proteins/metabolism , Cell Line , Disease Models, Animal , Drug Discovery , Drug Resistance, Microbial/drug effects , Drug Resistance, Microbial/genetics , Escherichia coli Proteins/antagonists & inhibitors , Escherichia coli Proteins/chemistry , Escherichia coli Proteins/genetics , Escherichia coli Proteins/metabolism , Female , Gastrointestinal Microbiome/drug effects , Gram-Negative Bacteria/genetics , Humans , Mice , Microbial Sensitivity Tests , Microbial Viability/drug effects , Mutation , Nematoda/microbiology , Operon/genetics , Photorhabdus/chemistry , Photorhabdus/genetics , Photorhabdus/isolation & purification , Substrate Specificity , Symbiosis
10.
PLoS One ; 14(11): e0224836, 2019.
Article in English | MEDLINE | ID: mdl-31714906

ABSTRACT

The opportunistic pathogen Escherichia coli, a common member of the human gut microbiota belonging to the Enterobacteriaceae family, is the causative agent of the majority of urinary tract infections (UTIs). The gut microbiota serves as a reservoir for uropathogenic E. coli where they are shed in feces, colonize the periurethral area, and infect the urinary tract. Currently, front line treatment for UTIs consists of oral antibiotics, but the rise of antibiotic resistance is leading to higher rates of recurrence, and antibiotics cause collateral damage to other members of the gut microbiota. It is commonly believed that incorporation of the American cranberry, Vaccinium macrocarpon, into the diet is useful for reducing recurrence of UTIs. We hypothesized such a benefit might be explained by a prebiotic or antimicrobial effect on the gut microbiota. As such, we tested cranberry extracts and whole cranberry powder on a human gut microbiome-derived community in a gut simulator and found that cranberry components broadly modulate the microbiota by reducing the abundance of Enterobacteriaceae and increasing the abundance of Bacteroidaceae. To identify the specific compounds responsible for this, we tested a panel of compounds isolated from cranberries for activity against E. coli, and found that salicylate exhibited antimicrobial activity against both laboratory E. coli and human UTI E. coli isolates. In a gut simulator, salicylate reduced levels of Enterobacteriaceae and elevated Bacteroidaceae in a dose dependent manner.


Subject(s)
Bacteroidaceae/growth & development , Enterobacteriaceae/growth & development , Gastrointestinal Microbiome , Models, Biological , Plant Extracts/pharmacology , Vaccinium macrocarpon/chemistry , Bacteroidaceae/drug effects , Enterobacteriaceae/drug effects , Escherichia coli/drug effects , Escherichia coli/isolation & purification , Gastrointestinal Microbiome/drug effects , Humans , Hydroxybenzoates/pharmacology , Microbial Sensitivity Tests , Powders , Salicylic Acid/pharmacology , Urinary Tract Infections/microbiology
11.
Article in English | MEDLINE | ID: mdl-30126963

ABSTRACT

Borrelia burgdorferi is the causative agent of Lyme borreliosis. Antibiotic therapy of early acute infection is effective for most patients, but 10 to 20% go on to develop posttreatment Lyme disease syndrome (PTLDS). The nature of PTLDS remains unknown, but currently approved antibiotics for the treatment of Lyme disease do not appear to impact these symptoms after they have developed. We reason that minimizing the time the pathogen interacts with the host will diminish the probability of developing PTLDS, irrespective of its nature. This calls for an efficient eradication of the pathogen during acute infection. In search of a superior killing antibiotic, we examined approved antibiotics for their ability to kill B. burgdorferi Vancomycin proved more effective in killing the pathogen in vitro than ceftriaxone, the standard of care for disseminated B. burgdorferi infection. Both compounds were also the most effective in killing stationary-phase cells. This is surprising, given that inhibitors of cell wall biosynthesis are known to only kill growing bacteria. We found that peptidoglycan synthesis continues in stationary-phase cells of B. burgdorferi, explaining this paradox. A combination of vancomycin and gemifloxacin sterilized a stationary-phase culture of B. burgdorferi Examination of the action of antibiotics in severe combined immunodeficient (SCID) mice showed that doxycycline, a standard of care for uncomplicated acute infection, did not clear the pathogen. In contrast, both ceftriaxone and vancomycin cleared the infection. A trial examining the early use of more potent antibiotics on the development of PTLDS may be warranted.


Subject(s)
Anti-Bacterial Agents/pharmacology , Borrelia burgdorferi/drug effects , Lyme Disease/drug therapy , Vancomycin/pharmacology , Aminoglycosides/pharmacology , Animals , Ceftriaxone/pharmacology , Doxycycline/pharmacology , Female , Mice , Mice, Inbred C3H , Mice, SCID , Microbial Sensitivity Tests/methods , Peptides/pharmacology
12.
Proc (Bayl Univ Med Cent) ; 31(3): 339-341, 2018 Jul.
Article in English | MEDLINE | ID: mdl-29904305

ABSTRACT

A 40-year-old woman presented to our stroke center for a left middle cerebral artery embolic occlusion. This was successfully treated with mechanical thrombectomy using a stent retriever and balloon guide catheter aspiration. The patient was discharged home in good condition on clopidogrel but returned 2 months later with a contralateral right middle cerebral artery embolic occlusion. This was also successfully treated, this time with a stent retriever and local aspiration (Sol-Arc technique). She was once again discharged in good condition but with warfarin and an implanted loop recorder. This case demonstrates the feasibility of short-term bilateral mechanical thrombectomy for embolic middle cerebral artery occlusions.

13.
Radiographics ; 38(2): 581-585, 2018.
Article in English | MEDLINE | ID: mdl-29528827

ABSTRACT

Editor's Note.-RadioGraphics continues to publish radiologic-pathologic case material selected from the American Institute for Radiologic Pathology (AIRP) "best case" presentations. The AIRP conducts a 4-week Radiologic Pathology Correlation Course, which is offered five times per year. On the penultimate day of the course, the best case presentation is held at the American Film Institute Silver Theater and Cultural Center in Silver Spring, Md. The AIRP faculty identifies the best cases, from each organ system, brought by the resident attendees. One or more of the best cases from each of the five courses are then solicited for publication in RadioGraphics. These cases emphasize the importance of radiologic-pathologic correlation in the imaging evaluation and diagnosis of diseases encountered at the institute and its predecessor, the Armed Forces Institute of Pathology (AFIP).


Subject(s)
Bronchial Neoplasms/diagnostic imaging , Paraganglioma/diagnostic imaging , Tomography, X-Ray Computed , Bronchial Neoplasms/pathology , Bronchial Neoplasms/surgery , Child , Contrast Media , Diagnosis, Differential , Humans , Male , Paraganglioma/pathology , Paraganglioma/surgery
15.
Proc (Bayl Univ Med Cent) ; 28(3): 337-9, 2015 Jul.
Article in English | MEDLINE | ID: mdl-26130881

ABSTRACT

We describe an 81-year-old man receiving azacitidine monotherapy for myelodysplastic syndrome who was improving from Listeria monocytogenes bacteremia after receiving antibiotic therapy during an earlier hospital admission. Shortly after discharge he developed new-onset seizure activity, with brain imaging on subsequent admissions demonstrating a posterior right frontal lobe mass. Specimen cultures after resection of the mass revealed this to be a cerebral abscess related to L. monocytogenes. Brain abscesses related to this organism are rare.

16.
J Antibiot (Tokyo) ; 63(8): 468-76, 2010 Aug.
Article in English | MEDLINE | ID: mdl-20648021

ABSTRACT

The vast majority of microbial species are 'uncultured' and do not grow under laboratory conditions. This has led to the development of a number of methods to culture these organisms in a simulated natural environment. Approaches include placing cells in chambers that allow diffusion of compounds from the natural environment, traps enclosed with porous membranes that specifically capture organisms forming hyphae--actinobacteria and microfungi, and growth in the presence of cultivable helper species. Repeated cultivation in situ produces domesticated variants that can grow on regular media in vitro, and can be scaled up for secondary metabolite production. The co-culture approach has led to the identification of the first class of growth factors for uncultured bacteria, iron-chelating siderophores. It appears that many uncultured organisms from diverse taxonomical groups have lost the ability to produce siderophores, and depend on neighboring species for growth. The new cultivation approaches allow for the exploitation of the secondary metabolite potential of the previously inaccessible microorganisms.


Subject(s)
Bacteria/growth & development , Bacteria/metabolism , Metabolome , Pharmaceutical Preparations/isolation & purification , Coculture Techniques/methods , Humans , Siderophores/metabolism
17.
Chem Biol ; 17(3): 254-64, 2010 Mar 26.
Article in English | MEDLINE | ID: mdl-20338517

ABSTRACT

The majority of bacterial species do not grow on synthetic media. Many non-growers require growth factors from other bacteria, but the nature of these compounds is largely unknown. We show here that previously uncultured isolates from marine sediment biofilm grow on a Petri dish in the presence of cultured organisms from the same environment. The growth factors produced by one cultured helper strain were identified as new acyl-desferrioxamine siderophores. A panel of previously uncultured isolates exhibited a range of siderophore promiscuity for growth promotion. This siderophore-based approach has enabled the culturing of organisms only distantly related to previously cultured microbes. The lack of growth in the laboratory for many strains from this habitat stems from an inability to autonomously produce siderophores, and the resulting chemical dependence on other microorganisms regulates community establishment in the environment.


Subject(s)
Deferoxamine/analogs & derivatives , Micrococcus/growth & development , Siderophores/metabolism , Soil Microbiology , Base Sequence , Biofilms , Deferoxamine/metabolism , Ecosystem , Geologic Sediments , Mass Spectrometry , Micrococcus/genetics , Micrococcus/metabolism , Microscopy, Electron, Scanning , Molecular Sequence Data , RNA, Bacterial/chemistry , RNA, Bacterial/genetics , Reverse Transcriptase Polymerase Chain Reaction , Spectrophotometry, Ultraviolet
18.
J Biol Chem ; 282(17): 13033-46, 2007 Apr 27.
Article in English | MEDLINE | ID: mdl-17324932

ABSTRACT

The inosine monophosphate cyclohydrolase (IMPCH) component (residues 1-199) of the bifunctional enzyme aminoimidazole-4-carboxamide ribonucleotide transformylase (AICAR Tfase, residues 200-593)/IMPCH (ATIC) catalyzes the final step in the de novo purine biosynthesis pathway that produces IMP. As a potential target for antineoplastic intervention, we designed IMPCH inhibitors, 1,5-dihydroimidazo[4,5-c][1,2,6]thiadiazin-4(3H)-one 2,2-dioxide (heterocycle, 1), the corresponding nucleoside (2), and the nucleoside monophosphate (nucleotide) (3), as mimics of the tetrahedral intermediate in the cyclization reaction. All compounds are competitive inhibitors against IMPCH (K(i) values = 0.13-0.23 microm) with the simple heterocycle 1 exhibiting the most potent inhibition (K(i) = 0.13 microm). Crystal structures of bifunctional ATIC in complex with nucleoside 2 and nucleotide 3 revealed IMPCH binding modes similar to that of the IMPCH feedback inhibitor, xanthosine 5'-monophosphate. Surprisingly, the simpler heterocycle 1 had a completely different IMPCH binding mode and was relocated to the phosphate binding pocket that was identified from previous xanthosine 5'-monophosphate structures. The aromatic imidazole ring interacts with a helix dipole, similar to the interaction with the phosphate moiety of 3. The crystal structures not only revealed the mechanism of inhibition of these compounds, but they now serve as a platform for future inhibitor improvements. Importantly, the nucleoside-complexed structure supports the notion that inhibitors lacking a negatively charged phosphate can still inhibit IMPCH activity with comparable potency to phosphate-containing inhibitors. Provocatively, the nucleotide inhibitor 3 also binds to the AICAR Tfase domain of ATIC, which now provides a lead compound for the design of inhibitors that simultaneously target both active sites of this bifunctional enzyme.


Subject(s)
Avian Proteins/antagonists & inhibitors , Enzyme Inhibitors/chemistry , Neoplasm Proteins/antagonists & inhibitors , Neoplasms/enzymology , Phosphoribosylaminoimidazolecarboxamide Formyltransferase/antagonists & inhibitors , Animals , Avian Proteins/chemistry , Avian Proteins/metabolism , Binding Sites , Birds/metabolism , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/metabolism , Enzyme Inhibitors/therapeutic use , Humans , Neoplasm Proteins/chemistry , Neoplasm Proteins/metabolism , Neoplasms/drug therapy , Nucleosides/chemical synthesis , Nucleosides/chemistry , Nucleosides/metabolism , Nucleotides/chemical synthesis , Nucleotides/chemistry , Nucleotides/metabolism , Phosphoribosylaminoimidazolecarboxamide Formyltransferase/chemistry , Phosphoribosylaminoimidazolecarboxamide Formyltransferase/metabolism , Protein Binding , Protein Structure, Tertiary , Purines/biosynthesis
19.
J Bacteriol ; 188(24): 8360-7, 2006 Dec.
Article in English | MEDLINE | ID: mdl-17041039

ABSTRACT

Overexpression of the HipA protein of the HipBA toxin/antitoxin module leads to multidrug tolerance in Escherichia coli. HipA is a "toxin" that causes reversible dormancy, whereas HipB is an antitoxin that binds HipA and acts as a transcriptional repressor of the hipBA operon. Comparative sequence analysis shows that HipA is a member of the phosphatidylinositol 3/4-kinase superfamily. The kinase activity of HipA was examined. HipA was autophosphorylated in the presence of ATP in vitro, and the purified protein appeared to carry a single phosphate group on serine 150. Thus, HipA is a serine kinase that is at least partially phosphorylated in vivo. Overexpression of HipA caused inhibition of cell growth and increase in persister formation. Replacing conserved aspartate 309 in the conserved kinase active site or aspartate 332 in the Mg2+-binding site with glutamine produced mutant proteins that lost the ability to stop cellular growth upon overexpression. Replacing serine 150 with alanine yielded a similarly inactive protein. The mutant proteins were then examined for their ability to increase antibiotic tolerance. Cells overexpressing wild-type HipA were highly tolerant to cefotaxime, a cell wall synthesis inhibitor, to ofloxacin, a fluoroquinolone inhibitor of DNA gyrase, and to topoisomerase IV and were almost completely resistant to killing by mitomycin C, which forms DNA adducts. The mutant proteins did not protect cells from cefotaxime or ofloxacin and had an impaired ability to protect from mitomycin C. Taken together, these results suggest that the protein kinase activity of HipA is essential for persister formation.


Subject(s)
Anti-Bacterial Agents/pharmacology , Drug Tolerance/physiology , Escherichia coli Proteins/metabolism , Escherichia coli/drug effects , Protein Serine-Threonine Kinases/metabolism , Amino Acid Sequence , Culture Media , Drug Tolerance/genetics , Escherichia coli/enzymology , Escherichia coli/genetics , Escherichia coli/growth & development , Escherichia coli Proteins/chemistry , Escherichia coli Proteins/genetics , Microbial Sensitivity Tests , Molecular Sequence Data , Point Mutation , Protein Serine-Threonine Kinases/chemistry , Protein Serine-Threonine Kinases/genetics
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