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New insight into the catabolic pathway redundancies of the dioxin-mineralizing bacterium Sphingomonas wittichii RW1

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Title
New insight into the catabolic pathway redundancies of the dioxin-mineralizing bacterium Sphingomonas wittichii RW1
Name (type = personal)
NamePart (type = family)
Eleya
NamePart (type = given)
Suha
NamePart (type = date)
1981-
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Suha Eleya
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RoleTerm (authority = RULIB)
author
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NamePart (type = family)
Zylstra
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Gerben
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Gerben Zylstra
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Advisory Committee
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chair
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Barkay
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Tamar
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Tamar Barkay
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Advisory Committee
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internal member
Name (type = personal)
NamePart (type = family)
Fennell
NamePart (type = given)
Donna
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Donna Fennell
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Advisory Committee
Role
RoleTerm (authority = RULIB)
internal member
Name (type = personal)
NamePart (type = family)
Kerkhof
NamePart (type = given)
Lee
DisplayForm
Lee Kerkhof
Affiliation
Advisory Committee
Role
RoleTerm (authority = RULIB)
outside member
Name (type = corporate)
NamePart
Rutgers University
Role
RoleTerm (authority = RULIB)
degree grantor
Name (type = corporate)
NamePart
School of Graduate Studies
Role
RoleTerm (authority = RULIB)
school
TypeOfResource
Text
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theses
OriginInfo
DateCreated (encoding = w3cdtf); (keyDate = yes); (qualifier = exact)
2020
DateOther (encoding = w3cdtf); (qualifier = exact); (type = degree)
2020-01
Language
LanguageTerm (authority = ISO 639-3:2007); (type = text)
English
Abstract (type = abstract)
Dioxins and dioxin-like compounds are highly toxic, ubiquitous polycyclic aromatic hydrocarbons with important environmental and human health impacts. Dioxins are listed among the most relevant environmental organic pollutants due to their high persistence and extreme lipophilicity. In recent years, a number of bacterial strains have been isolated and identified for their diverse metabolic capabilities to grow on and metabolize a broad range of environmentally recalcitrant compounds including, dibenzo-p-dioxin and dibenzofuran. Among these strains Sphingomonas wittichii RW1 has been one of the most effective dioxin degraders studied so far. RW1 is of great interest for its diverse metabolic activities and unusual genome structure. The complete genome sequence of RW1 reveals that this strain contains one chromosome and two circular megaplasmids referred to as pSWIT01 and pSWIT02. Many of the important catabolic genes that are involved in dibenzofuran and dibenzo-p-dioxin degradation are located on the small megaplasmid pSWIT02; particularly genes encoding the initial dioxygenase system DxnA1A2, a ferredoxin Fdx3, and a reductase RedA2. This unusual dioxygenase system initiates the oxygenolytic attack of dibenzofuran and dibenzo-p-dioxin in an angular fashion. Here we report the first physiological identification of the important proteins that together function as the initial dibenzofuran and dibenzo-p-dioxin dioxygenase enzyme in RW1. Knock out mutagenesis showed that two reductases RedA1 and RedA2 and two ferredoxins Fdx1 and Fdx3 are interchangeable where either RedA1/RedA2 in combination with Fdx1/Fdx3 can function as an electron donor to the terminal oxygenase. The knockout mutants were also screened on substrates other than dibenzofuran and dibenzo-p-dioxin such as salicylate and benzoate. We discovered that the reductase RedA2 is involved in supplying electrons to the salicylate oxygenase since deletion of the redA2 gene blocked the growth of RW1 on salicylate. Interestingly, single knockout mutants of redA1 and redA2 had no effect on RW1's ability to grow on benzoate while a double knockout mutant resulted in the loss of the ability to grow on benzoate. In addition, we constructed stable and unstable cloning vectors for sphingomonads based on the Sphingobium yanoikuyae B1 pKG2 plasmid and the Sphingomonas wittichii RW1 pSWIT02 plasmid. Stable vectors included the rep and par plasmid regions for replication and partitioning while unstable vectors included only the rep region. The stable vector pSEZ_RW1RP was used to cure RW1 of pSWIT02 by plasmid incompatibility. The cured strain RW1c was no longer able to grow on dibenzo-p-dioxin or dibenzofuran. A complementation test with the broad host range plasmid pRK415 carrying the initial dioxygenase system allows RW1c to grow on both dibenzo-p-dioxin and dibenzofuran. These results demonstrate that the only major role that pSWIT02 plays in the degradation of dibenzo-p-dioxin and dibenzofuran is to supply the initial dioxygenase responsible for the first step in the catabolic pathway.
Subject (authority = LCSH)
Topic
Sphingomonas
Subject (authority = RUETD)
Topic
Microbial Biology
RelatedItem (type = host)
TitleInfo
Title
Rutgers University Electronic Theses and Dissertations
Identifier (type = RULIB)
ETD
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ETD_10464
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application/pdf
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text/xml
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1 online resource (x, 95 pages) : illustrations
Note (type = degree)
Ph.D.
Note (type = bibliography)
Includes bibliographical references
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Title
School of Graduate Studies Electronic Theses and Dissertations
Identifier (type = local)
rucore10001600001
Location
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NjNbRU
Identifier (type = doi)
doi:10.7282/t3-438v-5j54
Genre (authority = ExL-Esploro)
ETD doctoral
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RightsDeclaration (ID = rulibRdec0006)
The author owns the copyright to this work.
RightsHolder (type = personal)
Name
FamilyName
Eleya
GivenName
Suha
Role
Copyright Holder
RightsEvent
Type
Permission or license
DateTime (encoding = w3cdtf); (qualifier = exact); (point = start)
2020-01-13 15:20:27
AssociatedEntity
Name
Suha Eleya
Role
Copyright holder
Affiliation
Rutgers University. School of Graduate Studies
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License
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Author Agreement License
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I hereby grant to the Rutgers University Libraries and to my school the non-exclusive right to archive, reproduce and distribute my thesis or dissertation, in whole or in part, and/or my abstract, in whole or in part, in and from an electronic format, subject to the release date subsequently stipulated in this submittal form and approved by my school. I represent and stipulate that the thesis or dissertation and its abstract are my original work, that they do not infringe or violate any rights of others, and that I make these grants as the sole owner of the rights to my thesis or dissertation and its abstract. I represent that I have obtained written permissions, when necessary, from the owner(s) of each third party copyrighted matter to be included in my thesis or dissertation and will supply copies of such upon request by my school. I acknowledge that RU ETD and my school will not distribute my thesis or dissertation or its abstract if, in their reasonable judgment, they believe all such rights have not been secured. I acknowledge that I retain ownership rights to the copyright of my work. I also retain the right to use all or part of this thesis or dissertation in future works, such as articles or books.
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Copyright protected
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Status
Open
Reason
Permission or license
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