Aspartate
homoserine
Lysine
threonine
homoserine-4P
isoleucine
*
4
Oxaloacetate
*
1
methionine
Homocysteine
Cystathionine
5–CH3-THFG
THFG
CbL-PLP
AAT-PLP
AAT/PAT-PLP
Pi
H 2 O
Pyruvate
+ NH 4
Proteins
glycine
serine
THF
5,10-CH2-THF
CgS-PLP
*
3
SO 4
2SH -
Cysteine
O-acetylserine
Acetate
Serine
OASTL-PLP
AdoMet
AdoHcy
AdoHcy
AdoMet
2
Sub-CH3
Sub
Sub
Sub-CH3
Proteins
AdoMet
Ethylene
dcAdoMet
ACC
ATP
P + PPi
spermine
spermidine
putrescine
arginine
MTA
* 6
MTR
MTR-P
MTRu-P
DHKMP
KMTB
ACS-PLP
Ornitine
adenine
*
1
O 2
HCOOH
H 2 O + Pi
ADP
ATP
H 2 O
agmatine
Thermospermine
?AAT/PAT-PLP
CO 2
Methionine Cycle
SAV1-PLP
methionine
AdoHcy
Substrate
Substrate-CH3
adenosine
Methyl cycle
Homocysteine
5
Asparagine
IPyA
Trp
Fig. 3 Interconnections in biosynthetic pathways of methionine, polyamines, ethylene, and AdoMet
and methionine salvage cycles in plants. Asterisk indicates aminotransferases targeted by AVG: 1,
eukaryotic aspartate aminotransferase (ET-AAT) and prokaryotic type aspartate/prephenate aminotransferase (PT-AAT/PAT); 2, O-acetylserine(thiol)lyase (OASTL); 3, cystathionine γ-lyase (CgL); 4,
cystathionine β-lyase (CbL); 5, aminotransferase SAV1/ISS1; 6, 1-aminocyclo-propane-1-carboxylate
synthase (ACS). Abbreviations used for metabolites are: AdoMet S-adenosylmethionine, dcAdoMet
decarboxylated S-adenosylmethionine, SAH S-adenosylhomocysteine, MTA 5
0 -methylthioadénosine,
MTR 5
0 -methylthioribose, MTR-P 5
0 -methylthioribose-phosphate, MTRu-P 5
0 -methylthioribulosephosphate, DHKMP 1,2-dihydro-3-oxo-5-methylthiopentene, KMTB 2-oxo-4-methylthiobutyrate;
Green boxes indicate plastidic location of enzymes. ? indicates putative aspartate aminotransferase
according to Pommerrenig et al. (2011) (adapted from Ravanel et al. 2004; Pommerrenig et al. 2011;
Sauter et al. 2013)
260
E. Le Deunff