Edwards EA

References (6)

Title : Screening and Characterization of Novel Polyesterases from Environmental Metagenomes with High Hydrolytic Activity against Synthetic Polyesters - Hajighasemi_2018_Environ.Sci.Technol_52_12388
Author(s) : Hajighasemi M , Tchigvintsev A , Nocek B , Flick R , Popovic A , Hai T , Khusnutdinova AN , Brown G , Xu X , Cui H , Anstett J , Chernikova TN , Bruls T , Le Paslier D , Yakimov MM , Joachimiak A , Golyshina OV , Savchenko A , Golyshin PN , Edwards EA , Yakunin AF
Ref : Environ Sci Technol , 52 :12388 , 2018
Abstract : The continuous growth of global plastics production, including polyesters, has resulted in increasing plastic pollution and subsequent negative environmental impacts. Therefore, enzyme-catalyzed depolymerization of synthetic polyesters as a plastics recycling approach has become a focus of research. In this study, we screened over 200 purified uncharacterized hydrolases from environmental metagenomes and sequenced microbial genomes and identified at least 10 proteins with high hydrolytic activity against synthetic polyesters. These include the metagenomic esterases MGS0156 and GEN0105, which hydrolyzed polylactic acid (PLA), polycaprolactone, as well as bis(benzoyloxyethyl)-terephthalate. With solid PLA as a substrate, both enzymes produced a mixture of lactic acid monomers, dimers, and higher oligomers as products. The crystal structure of MGS0156 was determined at 1.95 A resolution and revealed a modified alpha/beta hydrolase fold, with a lid domain and highly hydrophobic active site. Mutational studies of MGS0156 identified the residues critical for hydrolytic activity against both polyester and monoester substrates, with two-times higher polyesterase activity in the MGS0156 L169A mutant protein. Thus, our work identified novel, highly active polyesterases in environmental metagenomes and provided molecular insights into their activity, thereby augmenting our understanding of enzymatic polyester hydrolysis.
ESTHER : Hajighasemi_2018_Environ.Sci.Technol_52_12388
PubMedSearch : Hajighasemi_2018_Environ.Sci.Technol_52_12388
PubMedID: 30284819
Gene_locus related to this paper: 9zzzz-a0a0g3fj39 , 9zzzz-a0a0g3fj48 , 9zzzz-A0A0G3FEJ8 , 9bact-a4uz10

Title : Biochemical and Structural Insights into Enzymatic Depolymerization of Polylactic Acid and Other Polyesters by Microbial Carboxylesterases - Hajighasemi_2016_Biomacromolecules_17_2027
Author(s) : Hajighasemi M , Nocek BP , Tchigvintsev A , Brown G , Flick R , Xu X , Cui H , Hai T , Joachimiak A , Golyshin PN , Savchenko A , Edwards EA , Yakunin AF
Ref : Biomacromolecules , 17 :2027 , 2016
Abstract : Polylactic acid (PLA) is a biodegradable polyester derived from renewable resources, which is a leading candidate for the replacement of traditional petroleum-based polymers. Since the global production of PLA is quickly growing, there is an urgent need for the development of efficient recycling technologies, which will produce lactic acid instead of CO2 as the final product. After screening 90 purified microbial alpha/beta-hydrolases, we identified hydrolytic activity against emulsified PLA in two uncharacterized proteins, ABO2449 from Alcanivorax borkumensis and RPA1511 from Rhodopseudomonas palustris. Both enzymes were also active against emulsified polycaprolactone and other polyesters as well as against soluble alpha-naphthyl and p-nitrophenyl monoesters. In addition, both ABO2449 and RPA1511 catalyzed complete or extensive hydrolysis of solid PLA with the production of lactic acid monomers, dimers, and larger oligomers as products. The crystal structure of RPA1511 was determined at 2.2 A resolution and revealed a classical alpha/beta-hydrolase fold with a wide-open active site containing a molecule of polyethylene glycol bound near the catalytic triad Ser114-His270-Asp242. Site-directed mutagenesis of both proteins demonstrated that the catalytic triad residues are important for the hydrolysis of both monoester and polyester substrates. We also identified several residues in RPA1511 (Gln172, Leu212, Met215, Trp218, and Leu220) and ABO2449 (Phe38 and Leu152), which were not essential for activity against soluble monoesters but were found to be critical for the hydrolysis of PLA. Our results indicate that microbial carboxyl esterases can efficiently hydrolyze various polyesters making them attractive biocatalysts for plastics depolymerization and recycling.
ESTHER : Hajighasemi_2016_Biomacromolecules_17_2027
PubMedSearch : Hajighasemi_2016_Biomacromolecules_17_2027
PubMedID: 27087107
Gene_locus related to this paper: marav-a1u5n0 , rhopa-q6n9m9 , alcbs-q0vlq1

Title : Complete Genome Sequence of Bacteroidales Strain CF from a Chloroform-Dechlorinating Enrichment Culture - Tang_2013_Genome.Announc_1_e01066
Author(s) : Tang S , Edwards EA
Ref : Genome Announc , 1 : , 2013
Abstract : Bacteroidales strain CF is the most abundant nondechlorinating organism in a Dehalobacter-containing enrichment culture that consistently reductively dechlorinates >50 mg/liter chloroform or 1,1,1-trichloroethane (methyl chloroform). We assembled and closed the complete genome sequence of this organism from the metagenomic sequencing data for enrichment cultures. This organism is predicted to ferment l-lactate and ethanol.
ESTHER : Tang_2013_Genome.Announc_1_e01066
PubMedSearch : Tang_2013_Genome.Announc_1_e01066
PubMedID: 24356833
Gene_locus related to this paper: 9bact-u5q8g5 , 9bact-u5q334

Title : Semi-automatic in silico gap closure enabled de novo assembly of two Dehalobacter genomes from metagenomic data - Tang_2012_PLoS.One_7_e52038
Author(s) : Tang S , Gong Y , Edwards EA
Ref : PLoS ONE , 7 :e52038 , 2012
Abstract : Typically, the assembly and closure of a complete bacterial genome requires substantial additional effort spent in a wet lab for gap resolution and genome polishing. Assembly is further confounded by subspecies polymorphism when starting from metagenome sequence data. In this paper, we describe an in silico gap-resolution strategy that can substantially improve assembly. This strategy resolves assembly gaps in scaffolds using pre-assembled contigs, followed by verification with read mapping. It is capable of resolving assembly gaps caused by repetitive elements and subspecies polymorphisms. Using this strategy, we realized the de novo assembly of the first two Dehalobacter genomes from the metagenomes of two anaerobic mixed microbial cultures capable of reductive dechlorination of chlorinated ethanes and chloroform. Only four additional PCR reactions were required even though the initial assembly with Newbler v. 2.5 produced 101 contigs within 9 scaffolds belonging to two Dehalobacter strains. By applying this strategy to the re-assembly of a recently published genome of Bacteroides, we demonstrate its potential utility for other sequencing projects, both metagenomic and genomic.
ESTHER : Tang_2012_PLoS.One_7_e52038
PubMedSearch : Tang_2012_PLoS.One_7_e52038
PubMedID: 23284863
Gene_locus related to this paper: 9firm-w0ejt1

Title : Mapping the reaction coordinates of enzymatic defluorination - Chan_2011_J.Am.Chem.Soc_133_7461
Author(s) : Chan PW , Yakunin AF , Edwards EA , Pai EF
Ref : Journal of the American Chemical Society , 133 :7461 , 2011
Abstract : The carbon-fluorine bond is the strongest covalent bond in organic chemistry, yet fluoroacetate dehalogenases can readily hydrolyze this bond under mild physiological conditions. Elucidating the molecular basis of this rare biocatalytic activity will provide the fundamental chemical insights into how this formidable feat is achieved. Here, we present a series of high-resolution (1.15-1.80 A) crystal structures of a fluoroacetate dehalogenase, capturing snapshots along the defluorination reaction: the free enzyme, enzyme-fluoroacetate Michaelis complex, glycolyl-enzyme covalent intermediate, and enzyme-product complex. We demonstrate that enzymatic defluorination requires a halide pocket that not only supplies three hydrogen bonds to stabilize the fluoride ion but also is finely tailored for the smaller fluorine halogen atom to establish selectivity toward fluorinated substrates. We have further uncovered dynamics near the active site which may play pivotal roles in enzymatic defluorination. These findings may ultimately lead to the development of novel defluorinases that will enable the biotransformation of more complex fluorinated organic compounds, which in turn will assist the synthesis, detoxification, biodegradation, disposal, recycling, and regulatory strategies for the growing markets of organofluorines across major industrial sectors.
ESTHER : Chan_2011_J.Am.Chem.Soc_133_7461
PubMedSearch : Chan_2011_J.Am.Chem.Soc_133_7461
PubMedID: 21510690
Gene_locus related to this paper: rhopa-q6nam1

Title : Sequence- and activity-based screening of microbial genomes for novel dehalogenases - Chan_2010_Microb.Biotechnol_3_107
Author(s) : Chan WY , Wong M , Guthrie J , Savchenko AV , Yakunin AF , Pai EF , Edwards EA
Ref : Microb Biotechnol , 3 :107 , 2010
Abstract : Dehalogenases are environmentally important enzymes that detoxify organohalogens by cleaving their carbon-halogen bonds. Many microbial genomes harbour enzyme families containing dehalogenases, but a sequence-based identification of genuine dehalogenases with high confidence is challenging because of the low sequence conservation among these enzymes. Furthermore, these protein families harbour a rich diversity of other enzymes including esterases and phosphatases. Reliable sequence determinants are necessary to harness genome sequencing-efforts for accelerating the discovery of novel dehalogenases with improved or modified activities. In an attempt to extract dehalogenase sequence fingerprints, 103 uncharacterized potential dehalogenase candidates belonging to the alpha/beta hydrolase (ABH) and haloacid dehalogenase-like hydrolase (HAD) superfamilies were screened for dehalogenase, esterase and phosphatase activity. In this first biochemical screen, 1 haloalkane dehalogenase, 1 fluoroacetate dehalogenase and 5 l-2-haloacid dehalogenases were found (success rate 7%), as well as 19 esterases and 31 phosphatases. Using this functional data, we refined the sequence-based dehalogenase selection criteria and applied them to a second functional screen, which identified novel dehalogenase activity in 13 out of only 24 proteins (54%), increasing the success rate eightfold. Four new L-2-haloacid dehalogenases from the HAD superfamily were found to hydrolyse fluoroacetate, an activity never previously ascribed to enzymes in this superfamily.
ESTHER : Chan_2010_Microb.Biotechnol_3_107
PubMedSearch : Chan_2010_Microb.Biotechnol_3_107
PubMedID: 21255311
Gene_locus related to this paper: rhopa-q6nam1