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Research
in the Bogdanove laboratory (updated
August 9, 2011
)
Research in the Bogdanove
laboratory is grounded in plant bacteriology directed at understanding
mechanisms of bacterial plant pathogenesis and plant defense to develop
better means of disease control. We primarily study the interactions
of rice with pathovars of Xanthomonas oryzae, in which transcription
activator-like (TAL) effector proteins of the bacteria play an important
role. Despite the "-like," TAL effectors are, in fact, trans-kingdom,
positive-acting transcription factors. They are injected into plant cells
via the bacterial type III secretion system, imported into the plant cell
nucleus, and targeted to effector-specific sites (effector binding elements,
or EBEs) in the plant genome. TAL effector binding activates expression
of downstream genes, which may contribute to bacterial colonization, symptom
development, or pathogen dissemination (reviewed in Bogdanove et al.,
2010). We (Moscou and Bogdanove, 2009) and others discovered that TAL
effectors recognize their corresponding EBEs in a modular fashion: tandem,
polymorphic amino acid repeats in these proteins independently specify
single contiguous nucleotides in the DNA target. This correspondence of
repeat sequences and target nucleotides makes it possible to derive EBEs
for existing TAL effectors and to engineer novel TAL effectors with custom
assortments of repeats to bind DNA sequences of choice. Consequently,
TAL effectors have received much attention as DNA targeting tools. They
have been customized for targeted gene activation, both in plants and
in animal cells, and we and others have used them in combination with
a fused endonuclease to target DNA double strand breaks for genome engineering
(for a review, see Bogdanove and Voytas, 2011, in press). Much of our
work therefore centers on better understanding TAL effector
DNA targeting, developing improved TAL effector-derived DNA targeting
tools, and using those tools in plant genome engineering for disease resistance.
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