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Abstract Detail


Secondary Metabolism

Reichert, Angelika I [1], Dixon, R. A. [2].

Functional characterization of The PAL gene family in Nicotiana tabacum.

Phenylalanine ammonia lyase (PAL) plays a crucial function at the interface between primary and secondary plant metabolism. The enzyme catalyzes the first reaction in the phenylpropanoid pathway, the deamination of phenylalanine to form trans -cinnamic acid. Because of its importance in the formation of several plant natural products, e.g. lignin, flavonoids, hydroxycinnamic acids and condensed tannins, PAL is subject to strict regulation at the transcriptional and post-transcriptional levels. PAL is encoded by a small multigene family in most plants. Tobacco contains four PAL genes belonging to two subfamilies, but the biochemical properties pf the four corresponding enzymes have yet to be compared. To gain a better understanding of the complex regulation of PAL in tobacco, open reading frames encoding the tobacco PAL isoforms were cloned and expressed in E. coli. All His-tagged fusion proteins showed high activity with L-phenylalanine. Biochemical characterization revealed differences in their kinetic behavior. For one of the isoforms we observed cDNA clones in which a single amino acid mutation at the bottom of the substrate binding pocket results in an inactive enzyme - the physiological significance of this remains unclear.


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1 - The Samuel Roberts Noble Foundation, Plant Biology Division, 2510 Sam Noble Parkway, Ardmore, OK, 73401, USA
2 - The Samuel Roberts Noble Foundation, Plant Biology Division

Keywords:
phenylalanine ammonia lyase
tobacco
enzyme regulation.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P20046
Abstract ID:2060


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