scholarly journals Structural Analysis of The OXA-48 Carbapenemase Bound to A “Poor” Carbapenem Substrate, Doripenem

Antibiotics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 145 ◽  
Author(s):  
Krisztina M. Papp-Wallace ◽  
Vijay Kumar ◽  
Elise T. Zeiser ◽  
Scott A. Becka ◽  
Focco van den Akker
Keyword(s):  
Public Health ◽  
Crystal Structure ◽  
Salt Bridge ◽  
Hydrolytic Activity ◽  
Van Der Waals Interactions ◽  
Side Chain ◽  
Carbapenem Resistant ◽  
Mechanistic Basis ◽  
Further Development ◽  
Carbapenem Resistant Enterobacteriaceae

Carbapenem-resistant Enterobacteriaceae are a significant threat to public health, and a major resistance determinant that promotes this phenotype is the production of the OXA-48 carbapenemase. The activity of OXA-48 towards carbapenems is a puzzling phenotype as its hydrolytic activity against doripenem is non-detectable. To probe the mechanistic basis for this observation, we determined the 1.5 Å resolution crystal structure of the deacylation deficient K73A variant of OXA-48 in complex with doripenem. Doripenem is observed in the Δ1R and Δ1S tautomeric states covalently attached to the catalytic S70 residue. Likely due to positioning of residue Y211, the carboxylate moiety of doripenem is making fewer hydrogen bonding/salt-bridge interactions with R250 compared to previously determined carbapenem OXA structures. Moreover, the hydroxyethyl side chain of doripenem is making van der Waals interactions with a key V120 residue, which likely affects the deacylation rate of doripenem. We hypothesize that positions V120 and Y211 play important roles in the carbapenemase profile of OXA-48. Herein, we provide insights for the further development of the carbapenem class of antibiotics that could render them less effective to hydrolysis by or even inhibit OXA carbapenemases.

scholarly journals 1194. Carbapenem-Resistant Enterobacteriaceae in Kentucky: Initial 6 Months of Mechanism Testing

2018 ◽  
Vol 5 (suppl_1) ◽  
pp. S361-S361
Author(s):  
Kevin Spicer ◽  
Katelyn Cox ◽  
Rachel Zinner ◽  
Andrea Flinchum
Keyword(s):  
Public Health ◽  
Rural Areas ◽  
Demographic Data ◽  
Acute Care Hospital ◽  
The United States ◽  
Care Hospital ◽  
Local Data ◽  
Carbapenem Resistant ◽  
State And Local ◽  
Carbapenem Resistant Enterobacteriaceae

Abstract Background A global rise in carbapenem-resistant Enterobacteriaceae (CRE) has been noted over the past two decades. State and local data on CRE are necessary to better inform public health interventions. Methods Reporting of CRE (i.e., Enterobacteriaceae resistant to any carbapenem or shown to produce a carbapenemase) was mandated in Kentucky in 2015. Voluntary submission of isolates to the Antibiotic Resistance Laboratory Network regional laboratory for carbapenemase testing began September 2017. Demographic data collected as part of reporting included age, sex, county of residence, and inpatient/outpatient status. Descriptive and chi-square analyses were performed. Results Between September 1, 2017 and February 28, 2018, 149 CRE were reported to the Kentucky Department for Public Health. Testing for presence of a carbapenemase was performed on 115 isolates (77.2%); 44 (38.3%) were carbapenemase producing (CP)-CRE and Klebsiella pneumoniae carbapenemase (KPC) was identified from 38 (86.4%). Also identified were Verona integron-encoded metallo-β-lactamase (VIM; 5, 11.4%) and New Delhi metallo-β-lactamase (NDM; 1, 2.3%). Identification of carbapenemase varied among genera: Citrobacter (3/4, 75%), Klebsiella (21/40, 52.5%), Serratia (2/5, 40%), Escherichia (6/20, 30%), Enterobacter (11/41, 26.8%), Proteus (0/4, 0%), other genera (1/2, 50%). CRE isolates from urban or suburban areas were more likely CP-CRE than were those from rural areas (30/65, 46.2% vs. 14/50, 28%, P = 0.047). Carbapenemase was identified more often among CRE isolates from currently hospitalized patients than from patients whose cultures were collected outside of an acute care hospital (37/70, 52.8% vs. 7/45, 15.6%; P < 0.001). Conclusion The percentage of CRE that were CP-CRE in Kentucky was comparable with that reported for the United States (38 vs. 32%). Klebsiella spp., the genera historically associated with CP-CRE, made up less than half of CP-CRE. CP isolates were identified from urban, suburban, and rural settings and more frequently from isolates collected in hospitals compared with the community. The additional epidemiology obtained as part of this reporting system has identified metropolitan areas of the state as targets for CRE prevention efforts. Disclosures All authors: No reported disclosures.

scholarly journals 677. Activity of Novel β-Lactamase Inhibitor QPX7728 Combined with β-Lactam Agents When Tested Against Carbapenem-Resistant Enterobacteriaceae (CRE) Isolates

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S309-S309 ◽  
Author(s):  
Mariana Castanheira ◽  
Jill Lindley ◽  
Holly Huynh ◽  
Rodrigo E Mendes ◽  
Olga Lomovskaya
Keyword(s):  
Whole Genome Sequencing ◽  
Genome Sequencing ◽  
Inhibitory Activity ◽  
Multidrug Resistant ◽  
Whole Genome ◽  
Broth Microdilution ◽  
Carbapenem Resistant ◽  
Further Development ◽  
Lactamase Inhibitor ◽  
Carbapenem Resistant Enterobacteriaceae

Abstract Background CREs have been described worldwide and these isolates are often multidrug resistant with few therapeutic options remaining active against them. New β-lactam (BL)/β-lactamase inhibitor (BLI) combinations recently approved are active against KPC and some OXA-48 producers, but not against isolates producing metallo-β-lactamases (MBLs). We evaluated the activity of QPX7728 (QPX), a novel BLI paired with various BLs against a collection of CRE isolates characterized for the presence of carbapenemases. Methods A total of 508 CRE clinical isolates were susceptibility (S) tested by reference broth microdilution methods against meropenem (MER), tebipenem (TEB), cefepime (FEP), ceftolozane (TOL), and ertapenem (ETP), and meropenem (MEM) combined with QPX at fixed 2, 4, and 8 mg/L. Agents were provided by Qpex Biopharma except for FEP, ETP, and MEM. Carbapenemases were detected using PCR/sequencing or whole-genome sequencing. Results All BLs had limited activity against CRE isolates (MIC50/90, ≥32/ >32 mg/L) and QPX lowered the MIC for all agents (figure). Against 157 isolates carrying serine-carbapenemase (SCarb) genes (153 KPC-producers), MEM or ETP plus QPX at fixed 4 or 8 mg/L displayed MIC50 at ≤ 0.03 mg/L and MIC90 ranging from 0.12 to 0.5 mg/L. QPX lowered the FEP or TOL MIC50 to ≤ 0.25 mg/L and MIC90 to 0.25, 0.5 or 1 mg/L depending on the BLI concentration. Over 98.0% of the 150 isolates harboring OXA-48-like genes were inhibited by FEP, TOL, ETP or MEM plus QPX at ≤2 mg/L. Similarly, MEM, FEP, TOL and ETP + QPX inhibited >98.0% of the 51 CREs that did not carry carbapenemases at ≤2 mg/L when using a higher BLI concentration. The activity of FEP (MIC50/90, 0.06/1 mg/L), ETP (MIC50/90, 0.03/4 mg/L), and MEM (MIC50/90, ≤ 0.015/2 mg/L) was mostly restored when 8 mg/L of QPX was combined with these agents and tested against 150 MBL-producing isolates. Conclusion QPX restored the activity of several BLs when tested against 508 CRE isolates that include 157 harboring SCarb, 150 OXA-48-like-producers, and 150 MBL-producing isolates. Further development of this BLI with inhibitory activity against all carbapenemase types seems warranted. Disclosures All authors: No reported disclosures.

Structural basis of the transactivation deficiency of the human PPARγ F360L mutant associated with familial partial lipodystrophy

2014 ◽  
Vol 70 (7) ◽  
pp. 1965-1976 ◽  
Author(s):  
Clorinda Lori ◽  
Alessandra Pasquo ◽  
Roberta Montanari ◽  
Davide Capelli ◽  
Valerio Consalvi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Conformational Changes ◽  
Partial Agonist ◽  
Salt Bridge ◽  
Van Der Waals Interactions ◽  
Structural Basis ◽  
Wild Type ◽  
Partial Lipodystrophy ◽  
X Ray ◽  
Familial Partial Lipodystrophy

The peroxisome proliferator-activated receptors (PPARs) are transcription factors that regulate glucose and lipid metabolism. The role of PPARs in several chronic diseases such as type 2 diabetes, obesity and atherosclerosis is well known and, for this reason, they are the targets of antidiabetic and hypolipidaemic drugs. In the last decade, some rare mutations in human PPARγ that might be associated with partial lipodystrophy, dyslipidaemia, insulin resistance and colon cancer have emerged. In particular, the F360L mutant of PPARγ (PPARγ2 residue 388), which is associated with familial partial lipodystrophy, significantly decreases basal transcriptional activity and impairs stimulation by synthetic ligands. To date, the structural reason for this defective behaviour is unclear. Therefore, the crystal structure of PPARγ F360L together with the partial agonist LT175 has been solved and the mutant has been characterized by circular-dichroism spectroscopy (CD) in order to compare its thermal stability with that of the wild-type receptor. The X-ray analysis showed that the mutation induces dramatic conformational changes in the C-terminal part of the receptor ligand-binding domain (LBD) owing to the loss of van der Waals interactions made by the Phe360 residue in the wild type and an important salt bridge made by Arg357, with consequent rearrangement of loop 11/12 and the activation function helix 12 (H12). The increased mobility of H12 makes the binding of co-activators in the hydrophobic cleft less efficient, thereby markedly lowering the transactivation activity. The spectroscopic analysis in solution and molecular-dynamics (MD) simulations provided results which were in agreement and consistent with the mutant conformational changes observed by X-ray analysis. Moreover, to evaluate the importance of the salt bridge made by Arg357, the crystal structure of the PPARγ R357A mutant in complex with the agonist rosiglitazone has been solved.

scholarly journals Crystal structures of two monomeric triosephosphate isomerase variants identifiedviaa directed-evolution protocol selecting forL-arabinose isomerase activity

2016 ◽  
Vol 72 (6) ◽  
pp. 490-499
Author(s):  
Mirja Krause ◽  
Tiila-Riikka Kiema ◽  
Peter Neubauer ◽  
Rik K. Wierenga
Keyword(s):  
Crystal Structure ◽  
Escherichia Coli ◽  
Directed Evolution ◽  
Crystal Structures ◽  
Active Site ◽  
Triosephosphate Isomerase ◽  
Point Mutations ◽  
Van Der Waals Interactions ◽  
Side Chain ◽  
Arabinose Isomerase

The crystal structures are described of two variants of A-TIM: Ma18 (2.7 Å resolution) and Ma21 (1.55 Å resolution). A-TIM is a monomeric loop-deletion variant of triosephosphate isomerase (TIM) which has lost the TIM catalytic properties. Ma18 and Ma21 were identified after extensive directed-evolution selection experiments using anEscherichia coliL-arabinose isomerase knockout strain expressing a randomly mutated A-TIM gene. These variants facilitate better growth of theEscherichia coliselection strain in medium supplemented with 40 mML-arabinose. Ma18 and Ma21 differ from A-TIM by four and one point mutations, respectively. Ma18 and Ma21 are more stable proteins than A-TIM, as judged from CD melting experiments. Like A-TIM, both proteins are monomeric in solution. In the Ma18 crystal structure loop 6 is open and in the Ma21 crystal structure loop 6 is closed, being stabilized by a bound glycolate molecule. The crystal structures show only small differences in the active site compared with A-TIM. In the case of Ma21 it is observed that the point mutation (Q65L) contributes to small structural rearrangements near Asn11 of loop 1, which correlate with different ligand-binding properties such as a loss of citrate binding in the active site. The Ma21 structure also shows that its Leu65 side chain is involved in van der Waals interactions with neighbouring hydrophobic side-chain moieties, correlating with its increased stability. The experimental data suggest that the increased stability and solubility properties of Ma21 and Ma18 compared with A-TIM cause better growth of the selection strain when coexpressing Ma21 and Ma18 instead of A-TIM.

scholarly journals Phylogenetically Diverse Escherichia Coli Strains From Chicken Co-Harbour Multiple Carbapenemase Encoding Genes (blaNDM-blaOXA-blaIMP)

2020 ◽  
Author(s):  
Erkihun Aklilu ◽  
Azian Harun ◽  
Kirnpal Kaur Banga Singh ◽  
Shamsaldeen Ibrahim ◽  
Nor Fadhilah Kamaruzzaman
Keyword(s):  
Public Health ◽  
Phylogenetic Diversity ◽  
Farm Animals ◽  
E Coli ◽  
Carbapenem Resistant ◽  
Resistance Patterns ◽  
Phylogenetic Grouping ◽  
Encoding Genes ◽  
Potential Public Health ◽  
Carbapenem Resistant Enterobacteriaceae

Carbapenem resistant Enterobacteriaceae (CRE) has been public health risk in several countries and recent reports indicate the emergence of CRE in food animals. This study was conducted to investigate the occurrence, resistance patterns, and phylogenetic diversity of CRE E.coli from chicken. Routine bacteriology, PCR detection of E.coli species, multiplex PCR to detect carbapenemase encoding genes and phylogeny of CRE E. coli were conducted. The results show that 24.36 % (19/78) were identified as CRE based on the phenotypic identifications of which 17 were positive for the tested carabanemase genes. The majority, 57.99% (11/19) of the isolates harbored multiple carbapenemase genes. Four isolates harbored all blaNDM blaOXA, blaIMP, five and two different isolates harbored blaNDM and blaOXA, and blaOXA and blaIMP respectively. The Meropenem, Imipenem and Ertapenem MIC values for the isolates ranged from 2g/mL to ≥256g/mL. Phylogenetic grouping showed that the CRE E.coli isolates belonged to five different groups; groups A, B1, C, D and unknown. The detection of carbapenem resistant E.coli in this study shows that CRE is has become an emerging problem in farm animals, particularly, in poultry farms. This also implies the potential public health risks posed by CRE from chicken to the consumers.

scholarly journals Conformation and supramolecular arrangement of 1,3:2,4-dibenzyli-dene-D-sorbitol in solution and in single crystals

2021 ◽  
Author(s):  
Fernán Berride ◽  
Victor M. Sánchez-Pedregal ◽  
Bruno Dacuña ◽  
Eurico Cabrita ◽  
Armando Navarro-Vázquez ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Nmr Spectroscopy ◽  
Van Der Waals Interactions ◽  
Side Chain ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Intermolecular Hydrogen Bonds ◽  
X Ray ◽  
Definitive Evidence ◽  
Phenyl Rings

The X-ray crystal structure of the gelator 1,3:2,4-dibenzylidene-D-sorbitol (DBS) is reported here. DBS is an important gelating molecule known for nearly 130 years, that has eluded crystallization until now. The crystal obtained presents an axial stacking of DBS molecules stabilized by both Van der Waals interactions and intermolecular hydrogen bonds of the side chain hydroxyl groups with either neighboring DBS or water molecules. The crystal structure shows definitive evidence for the frequently assumed “butterfly” type aggregation mode and experimentally proves the equatorial placement of the phenyl rings. The conformation of DBS has been analyzed in the crystal structure and compared with that determined in solution through NMR spectroscopy.

scholarly journals A review on bacterial resistance to carbapenems: epidemiology, detection and treatment options

2020 ◽  
Vol 6 (3) ◽  
pp. FSO438 ◽  
Author(s):  
Ann A Elshamy ◽  
Khaled M Aboshanab
Keyword(s):  
Public Health ◽  
Bacterial Resistance ◽  
Antimicrobial Agents ◽  
Treatment Options ◽  
Carbapenem Resistance ◽  
Multidrug Resistant ◽  
Mechanisms Of Resistance ◽  
Carbapenem Resistant ◽  
Public Health Threat ◽  
Carbapenem Resistant Enterobacteriaceae

Carbapenems are a class of antimicrobial agents reserved for infections caused by multidrug-resistant microorganisms. The emergence of carbapenem resistance has become a serious public health threat. This type of antimicrobial resistance is spreading at an alarming rate, resulting in major outbreaks and treatment failure of community-acquired and nosocomial infections caused by the clinically relevant carbapenem-producing Enterobacteriaceae or carbapenem-resistant Enterobacteriaceae. This review is focused on carbapenem resistance, including mechanisms of resistance, history and epidemiology, phenotypic and genotypic detection in the clinically relevant bacterial pathogens and the possible treatment options available.

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