Characterization of an Isoflavonoid-Specific Prenyltransferase from Lupinus albus Page: 70
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Characterization of an Isoflavonoid-Specific
Prenyltransferase from Lupinus albusl[W][OA]
Guoan Shen, David Huhman, Zhentian Lei, John Snyder, Lloyd W. Sumner, and Richard A. Dixon*
Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401
Prenylated flavonoids and isoflavonoids possess antimicrobial activity against fungal pathogens of plants. However, only a few
plant flavonoid and isoflavonoid prenyltransferase genes have been identified to date. In this study, an isoflavonoid
prenyltransferase gene, designated as LaPT1, was identified from white lupin (Lupinus albus). The deduced protein sequence
of LaPT1 shared high homologies with known flavonoid and isoflavonoid prenyltransferases. The LaPT1 gene was mainly
expressed in roots, a major site for constitutive accumulation of prenylated isoflavones in white lupin. LaPT1 is predicted to be a
membrane-bound protein with nine transmembrane regions and conserved functional domains similar to other flavonoid and
isoflavonoid prenyltransferases; it has a predicted chloroplast transit peptide and is plastid localized. A microsomal fraction
containing recombinant LaPT1 prenylated the isoflavone genistein at the B-ring 3' position to produce isowighteone. The
enzyme is also active with 2'-hydroxygenistein but has no activity with other flavonoid substrates. The apparent Km of
recombinant LaPT1 for the dimethylallyl diphosphate prenyl donor is in a similar range to that of other flavonoid
prenyltransferases, but the apparent catalytic efficiency with genistein is considerably higher. Removal of the transit peptide
increased the apparent overall activity but also increased the Km. Medicago truncatula hairy roots expressing LaPT1 accumulated
isowighteone, a compound that is not naturally produced in this species, indicating a strategy for metabolic engineering of novel
antimicrobial compounds in legumes.
Prenylated flavonoids and isoflavonoids have long
been known to possess unique bioactivities relative to
their unmodified parent compounds, particularly po-
tent antimicrobial activity against fungal pathogens
(Harborne et al., 1976). This enhanced bioactivity likely
results from the presence of the lipophilic prenyl side
chain, which facilitates the transmembrane transport
of these compounds (Harborne et al., 1976).
The prenylation of flavonoids and isoflavonoids is
catalyzed by plant membrane proteins located in
plastids (Laflamme et al., 1993; Sasaki et al., 2008;
Akashi et al., 2009). However, only a few flavonoid
prenyltransferase genes have been identified to date,
due to difficulties associated with the study of mem-
brane proteins. These newly identified genes include
naringenin 8-prenyltransferase (SfN8DT-1), genistein
6-prenyltransferase (SfG6DT-1), and isoliquiritigenin
dimethylallyltransferase (SfiLDT) from Sophoraflavescens
1 This work was supported by the State of Oklahoma Consortium
for Legume Research and the Samuel Roberts Noble Foundation. The
confocal microscope used in this study was funded by the National
Science Foundation Major Research Instrumentation program (grant
* Corresponding author; e-mail firstname.lastname@example.org.
The author responsible for distribution of materials integral to the
findings presented in this article in accordance with the policy de-
scribed in the Instructions for Authors (www.plantphysiol.org) is:
Richard A. Dixon (email@example.com).
[W] The online version of this article contains Web-only data.
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(Sasaki et al., 2008, 2011) and a pterocarpan
4-dimethylallyltransferase (G4DT) from soybean (Gly-
cine max; Akashi et al., 2009).
In addition to S. flavescens and soybean, prenylated
isoflavonoids are commonly found in several legume
species, for example white lupin (Lupinus albus) and
other Lupinus species (Harborne et al., 1976; Schrider
et al., 1979; Tahara et al., 1984, 1989; Gagnon et al.,
1992; Katagiri et al., 2000; Bednarek et al., 2001). In
contrast to the typical microbially induced synthesis of
isoflavonoid defense compounds in many plant spe-
cies, Lupinus species constitutively produce various
monoprenylated and diprenylated isoflavonoids, with
the major components being genistein derivatives
such as wighteone (6-prenylgenistein), isowighteone
(3'-prenylgenistein), and lupiwighteone (8-prenylgenistein;
Fig. 1), in addition to minor amounts of cyclized
pyrano derivatives (Harborne et al., 1976; Schroder
et al., 1979; Tahara et al., 1984, 1989; Gagnon et al.,
1992; Katagiri et al., 2000; Bednarek et al., 2001).
Lupinus species, therefore, are good model plants for
studying the biosynthesis of prenylated aromatic
compounds. The accumulation of such compounds in
Lupinus species is further increased by exposure to
either biotic or abiotic elicitors (Schrider et al., 1979;
Shibuya et al., 1992; Gagnon and Ibrahim, 1997). En-
zymes responsible for the prenylation reactions have
been shown to be membrane bound (Schrider et al.,
1979; Laflamme et al., 1993). However, genes encod-
ing lupin isoflavone prenyltransferases have not yet
We here report the characterization of an isoflavone
prenyltransferase from white lupin named LaPT1.
Plant Physiology, May 2012, Vol. 159, pp. 70-80, www.plantphysiol.org 2012 American Society of Plant Biologists. All Rights Reserved.
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Shen, Guoan; Huhman, David; Lei, Zhentian; Snyder, John; Sumner, Lloyd W. & Dixon, R. A. Characterization of an Isoflavonoid-Specific Prenyltransferase from Lupinus albus, article, May 2012; [Rockville, Maryland]. (digital.library.unt.edu/ark:/67531/metadc282594/m1/1/: accessed April 25, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT College of Arts and Sciences.