Completing the Methionine Salvage Cycle in Bacteria and Plants

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Material Information

Title:
Completing the Methionine Salvage Cycle in Bacteria and Plants
Physical Description:
1 online resource (103 p.)
Language:
english
Creator:
Ellens, Kenneth W
Publisher:
University of Florida
Place of Publication:
Gainesville, Fla.
Publication Date:

Thesis/Dissertation Information

Degree:
Doctorate ( Ph.D.)
Degree Grantor:
University of Florida
Degree Disciplines:
Plant Molecular and Cellular Biology
Committee Chair:
HANSON,ANDREW D
Committee Co-Chair:
KLEE,HARRY JOHN
Committee Members:
GREGORY,JESSE F,III
DE CRECY,VALERIE ANNE
PURICH,DANIEL L

Subjects

Subjects / Keywords:
biochemistry -- metabolism -- omega-amidase -- transaminase
Plant Molecular and Cellular Biology -- Dissertations, Academic -- UF
Genre:
Plant Molecular and Cellular Biology thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract:
S-Adenosylmethionine is converted enzymatically and nonenzymatically to methylthioadenosine, which is recycled to methionine (Met) via a salvage pathway. In plants and bacteria, enzymes for all steps in this pathway are known except the last: transamination of alpha-ketomethylthiobutyrate to give Met. In mammals, glutamine transaminase K (GTK) and omega-amidase (omega-Am) are thought to act in tandem to execute this step, with GTK forming alpha-ketoglutaramate, which omega-Am hydrolyzes. Comparative genomics indicated that GTK and omega-Am could function likewise in plants and bacteria because genes encoding GTK and omega-Am homologs (i) co-express with the Met salvage gene 5-methylthioribose kinase in Arabidopsis, and (ii) cluster on the chromosome with each other and with Met salvage genes in diverse bacteria. Consistent with this possibility, tomato, maize, and Bacillus subtilis GTK and omega-Am homologs had the predicted activities: GTK was specific for glutamine as amino donor and strongly preferred alpha-ketomethylthiobutyrate as amino acceptor, and omega-Am strongly preferred alpha-ketoglutaramate. Also consistent with this possibility, plant GTK and omega-Am were localized to the cytosol, where the Met salvage pathway resides, as well as to organelles. This multiple targeting was shown to result from use of alternative start codons. In B. subtilis, ablating GTK did not inhibit growth on 5-methylthioribose as sole sulfur source, and ablating omega-Am had only a mild effect. Collectively, these data indicate that while GTK, coupled with omega-Am, is positioned to support significant Met salvage flux in plants and bacteria, it can probably be replaced by other aminotransferases.
General Note:
In the series University of Florida Digital Collections.
General Note:
Includes vita.
Bibliography:
Includes bibliographical references.
Source of Description:
Description based on online resource; title from PDF title page.
Source of Description:
This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility:
by Kenneth W Ellens.
Thesis:
Thesis (Ph.D.)--University of Florida, 2014.
Local:
Adviser: HANSON,ANDREW D.
Local:
Co-adviser: KLEE,HARRY JOHN.
Electronic Access:
RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2016-05-31

Record Information

Source Institution:
UFRGP
Rights Management:
Applicable rights reserved.
Classification:
lcc - LD1780 2014
System ID:
UFE0046569:00001