HOW DO PLANTS RECOGNIZE FUNGI ?
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Transcript of HOW DO PLANTS RECOGNIZE FUNGI ?
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Characterization of MAMPs from Penicillium chrysogenum
Yunzi Gou
Supervisor :
Martin Lipschis
Prof. Georg Felix
HOW DO PLANTS RECOGNIZE FUNGI ?
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MAMPs/PAMPs:Microbe-associated molecular patterns / Pathogen-associated molecular patterns
Defence signaling & responses
Flagellin(flg22)
EF-Tu(elf18)…
Molecules shared by large groups of microbes but absent from the host
Highly conserved structure Recognized by Pattern recognition
receptors (PRRs , e.g. FLS2, EFR) Induce PTI(PAMP-triggered
immunity) at nanomolar concentration
ChitinErgosterol
…
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signaling cascade +++
K+
H+
Cl-
Ca2+
NADPHoxidasecomplex
O2+ O2
- H2O2
ethylene
Methioninecycle
ACC
ca. 5 min
ca. 10-30 min
pH
assay
eth
yle
ne a
ssay
PAMP induced defence reactions
MAPKKK
MAPKK MAPK
Gene activation
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PEN
Pen : extract from a high penicillin-producing strain of P. chrysogenum .
bulk waste product from Sandoz, Kundl, Austria:
mycelium after extraction of penicillin, dried, heated for 3h at 140°C ….
penicillin or its by-product have no MAMP-activity on plants
InduceDefence response
B. Thuerig et al. PMPP (2006)
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A. thaliana
extracellular alkalinisation ethylene
biosynthesis
PENPEN
B. Thuerig et al. / Physiological and Molecular Plant Pathology (2006)
PEN : Strong MAMP-activityPEN : Strong MAMP-activity
in a broad range !in a broad range !
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Ion exchange chromatography
size exclusion chromatography
C8 and C18 reversed phase chromatography
B. Thuerig et al. PMPP, 2006.
No distinct peaks Activity was spread
over a wide range of fractions
APPROACHS TO PURIFY...
The MAMP-activity of Pen is The MAMP-activity of Pen is heterogeneousheterogeneous in polarity, in polarity, size and size and chargecharge
A MAMP has structural diversity ?
ORA mixture of different
MAMPs ?
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Pen• Crude extract• Aqueous solution (45mg/ml)
Pen1000
• Dialysed in 1kD cut-off membrane• Get rid of small chitin fragments &
other small molecule
Penpre
• Pre-purified on C18 RP pre-column with 0,1% TFA
• Eluted with Methanol
CHARACTORIZATION & PURIFICATION
• C18 reversed phase chromatography
• Eluted with Methanol gradientHPLC
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HPLC
• C18 reversed phase chromatography• Eluted with Methanol gradient
-Column : VP250/10 NUCLEOSIL 120-10 C18-Buffer A : 0,1% TFA-Buffer B : 95% MeOH 0,1%TFA-Gradient : 0-60% B in 30 ml, 60%-100%B in 0,1s-Fraction : 1 mlElultion Volume (ml)
pH assay:
• 1µl from each fraction• 400µl Arabidopsis cell culture• pH measured after 25 min
No single sharp peak but 2 giant “hills„ No single sharp peak but 2 giant “hills„
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Are they the same MAMP-activity in principle ?
Saturation experiment -Saturate PRRs for C -Add D to the same A.thaliana cells…
Different type of MAMP-activity, D is stronger than C D may contain some C
Time(min)
control
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Are these 2 type of MAMP-activity sensitive to protease ?
-No prot.K inhibitor presence in C & D
- Protease digestion does have a small effect on both activities
-But it is not a dramatic decrease of activity like it is in the case of proteinic MAMP (elf18).
C & D unlikely protein
time (min)time (min)
elf18 was digested in D5, 0,3µl D5 was added.
time (min)
• Control : Prot.K worked
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Are they the same MAMP-activity as Chitin ? Saturation experiment -Saturate PRRs for Chitin -Add C & D to the same cells…
300µg Chitin / ml cell culture
900µg Chitin
Not the same as chitin D seems containing more non-chitin activity than C
Chitinase digestion of C & D
C is more sensitive to chitinase than DD contains more non-chitin activity than C !
Control:chitinase worked
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Can both of them induce ethylene response ?
C contains major chitin-like activity D contains a good ethylene-inducing MAMP-activity
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Protease digestion of D after chitinase treatment
-Similar small effect observed again
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SUMMARY
Proteinaceous activity
A weak proteinic PAMP ?
or
Only the peptide part linked to D ?
Probably overlaped !
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Find ways to purify D from Pen which is largely contaminated by Chitin & CLP
Characterize ConA-binding activity of Pen
Screen for DP-recepter mutant using ethylene bioassay
OUTLOOK
overlapping