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Abstract Detail


Metabolism

Tovar-Mendez, Alejandro [1], Broz, Amanda [2], Miernyk, Jan A [3], Randall, Douglas D [4].

Can the three Arabidopsis thaliana isozymes of mitochondrial dihydrolipoylacetyltransferase assemble into PDC hetero-cores?

The pentagonal-dodecahedron core structure of the mitochondrial pyruvate dehydrogenase complex is assembled from 60 dihydrolipoylacetyltransferase (E2) subunits. Depending upon the source, E2 primary sequences include one to three N-terminal lipoyl domains, followed by a subunit binding domain and a C-terminal catalytic and assembly domain. Plants have two distinct forms of mtE2, a mono-lipoyl domain form that is apparently ubiquitous, and a di-lipoyl domain form which has only been identified in dicots. Three mtPDC E2 sequences were identified in the Arabidopsis thaliana genome: two contain one lipoyl domain (E2IA and E2IB), and one contains two lipoyl domains (E2II). The E2IA and E2IB deduced amino acid sequences are over 85% identical to each other, and both are 50% identical to E2II. Recombinant E2IB is 40 times more catalytically active in vitro. All three recombinant AtE2 isozymes can individually form 60mer icosahedral PDC cores, as visualized by negative staining TEM. We have now used bimolecular fluorescence complementation analysis of E2:GFP chimera to show that in bacteria all three forms are capable of hetero-core formation.


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1 - University of Missouri-Columbia, Department of Biochemistry, 117 Schweitzer Hall, Columbia, MO, 65211, USA
2 - Colorado State University, Department of Horticulture and Landscape Architecture
3 - University of Missouri-Columbia, Department of Biochemistry and Plant Genetics Research Unit, USDA ARS.
4 - University of Missouri-Columbia, Department of Biochemistry

Keywords:
Arabidopsis
bimolecular fluorescence complementation
enzymology
pyruvate dehydrogenase complex.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P19034
Abstract ID:1502


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