5.4.4.2 evolution genes ATICS1 and AtICS2 are both located on chromosome 1 on different sides of the centromere, and they are likely a result of a duplication event, since they are bordered by similar genes. At the DNA sequence level, the protein-coding regions of the two genes share a high degree of similarity, but this does not extend into the untranslated regions 747030 5.4.4.2 evolution PchA is a member of the MST, i.e. menaquinone, siderophore and tryptophan, family of enzymes 726817 5.4.4.2 evolution the predicted ICS protein has high amino acid sequence identity to its orthologues and possesses a conserved chorismate binding site belonging to the supergene family of chorismate binding proteins 749121 5.4.4.2 malfunction mutation sed111 in the gene salicylic acid induction-deficient 2 (SID2), which encodes isochorismate synthase 1. Mutation sed111 belongs to a series of mutants called suppressor of esd4 (sed), which delay flowering, enhance growth and reduce hyperaccumulation of SUMO conjugates. Mutations in the SUMO protease early in short days 4 (ESD4) cause hyperaccumulation of conjugates formed between SUMO and its substrates, and phenotypically are associated with extreme early flowering and impaired growth. Elevated salicylic acid levels conferred by increased expression of isochorismate synthase 1 contribute to hyperaccumulation of SUMO1 conjugates in the Arabidopsis thaliana mutant early in short days 4. Compared to wild-type plants, esd4 contains higher levels of SID2 mRNA and about threefold more salicylate, whereas sed111 contains lower salicylate levels 748944 5.4.4.2 malfunction significant reduction in the expression of ICS1 during immune responses is observed in the tcp8/tcp9 double mutant -, 748946 5.4.4.2 malfunction the redox status of the plastoquinone pool in knockout mutant ics1 shows significant variation depending on the leaf age. Mutant plants treated with a phylloquinone precursor display symptoms of phenotypic reversion towards the wild type. The ics1 mutant also shows altered thylakoid structure with an increased number of stacked thylakoids per granum -, 728058 5.4.4.2 metabolism enzyme ICS does not act as isochorismate pyruvate lyase (IPL, EC 4.2.99.21) and bifunctional salicylate synthase, it does not convert chorismate into salicylate. In Arabidopsis thaliana, salicylate is synthesized from chorismic acid, derived from the shikimic acid pathway, occuring in the plastid 747030 5.4.4.2 metabolism isochorismate synthase 1 is a key enzyme in salicylate biosynthesis in Arabidopsis thaliana. The TCP family transcription factor AtTCP8 is a regulator of isozyme ICS1, it binds to a typical TCP binding site in the ICS1 promoter. Expression patterns of TCP8 and its corresponding gene TCP9 largely overlap with ICS1 under pathogen attack. Strong interactions between TCP8 and SAR deficient 1 (SARD1), WRKY family transcription factor 28 (WRKY28), NAC (NAM/ATAF1, ATAF2/CUC2) family transcription factor 019 (NAC019), as well as among TCP8, TCP9 and TCP20, implying a complex coordinated regulatory mechanism underlying ICS1 expression. There is a strong negative regulatory region between -128 and -316 bp, and the binding of repressor(s) to this region may be necessary for suppression of ICS1 expression during plant growth and development, TCP8 can bind at this region, while TCP5, TCP11 and TCP19 appear not to bind to the promoter region. TCP8 specifically binds to the TCP binding site in the ICS1 promoter in vitro and in vivo. Trans-activation capability of TCP8. TCP8/TCP9 positively regulate ICS1 expression with redundancy upon pathogen infection, and TCPs are involved in maintaining ICS1 expression, yeast one-hybrid (Y1H) screening and transactivation activity assay, detailed overview -, 748946 5.4.4.2 metabolism key enzyme in the isochorismate pathway 728533 5.4.4.2 metabolism salicylic acid is synthesized via the phenylalanine lyase (PAL) and isochorismate synthase (ICS) pathways and can influence the stress response in plants by regulating certain secondary metabolites. Both free salicylate and total salicylate are positively correlated with PAL, ICS, and baicalin, but negatively correlated with baicalein, overview 749121 5.4.4.2 metabolism the bifunctional salicylate synthase converts chorismate into salicylate through a two-step reaction, exhibiting both isochorismate synthase (EC 5.4.4.2) and isochorismate lyase (EC 4.2.99.21) activities 748448 5.4.4.2 metabolism the enzyme produces isochorismate for conversion to salicylate by isochorismate-pyruvate lyase, PchB, and incorporation into the pyochelin siderophore. Isochorismate synthase (PchA) and isochorismate-pyruvate lyase (PchB) from Pseudomonas aeurginosa are involved in the synthesis of the siderophore pyochelin 726963 5.4.4.2 metabolism the first committed step during the biosynthesis of siderophores, which are small molecules capable of chelating iron from the host organism, is the conversion of chorismate into isochorismate by isochorismate synthase (EC 5.4.4.2) and consequently to salicylate by isochorismate pyruvate-lyase (EC 4.2.99.21). Salicylate synthase converts chorismate into salicylate through a two-step reaction 747617 5.4.4.2 metabolism the first committed step during the biosynthesis of siderophores, which are small molecules capable of chelating iron from the host organism, is the conversion of chorismate into isochorismate by isochorismate synthase (EC 5.4.4.2) and consequently to salicylate by isochorismate pyruvate-lyase (EC 4.2.99.21). the bifunctional salicylate synthase converts chorismate into salicylate through a two-step reaction, exhibiting both isochorismate synthase (EC 5.4.4.2) and isochorismate lyase (EC 4.2.99.21) activities -, 747617 5.4.4.2 additional information enzyme structure comparisons and analysis, active site structure, overview. Ala304 plays an important role in positioning the peptide-bond carbonyl, enabling the formation of a proper hydrogen bond to the isochorismate C2 hydroxyl -, 726636 5.4.4.2 additional information enzyme three-dimensional structure analysis, the lysine residue, Lys190, might be involved in the activation of water molecules and the subsequent nucleophilic attack on the C2 carbon of chorismate without directly involving the magnesium ion, participation of the Lys residue during the activation of the substrate or nucleophilic agent 747617 5.4.4.2 additional information homology modeling of isozymes ICS1 and ICS2 using Serratia marcescens anthranilate synthase (TrpE, PDB ID 1I7Q) as reference structure 747030 5.4.4.2 additional information solvent kinetic isotope effects, overview 726817 5.4.4.2 additional information structure-function relationships of chorismate-utilizing enzymes, structure comparisons, overview. Isochorismate synthase cannot perform any pericyclic reaction. Residues K221 and E269 are general base and acid, respectively 726963 5.4.4.2 physiological function Arabidopsis ICS1 represents a divergent isoform for inducible salicylic acid synthesis during defense 706530 5.4.4.2 physiological function chorismate-utilizing enzymes (CUE) such as chorismate mutase, anthranilate synthase, chorismate pyruvate-lyase, 4-amino-4-deoxychorismate synthase, isochorismate synthase and salicylate synthase are responsible for converting chorismate into various products necessary for the survival of bacteria 747617 5.4.4.2 physiological function isochorismate synthase 1 is required for salicylate biosynthesis. SUMO homeostasis influences salicylate biosynthesis in wild-type plants, and also demonstrate that elevated levels of salicylate strongly increase the abundance of SUMO conjugates 748944 5.4.4.2 physiological function isozyme AtICS1 is required for increased salicylate biosynthesis in response to pathogens, and its expression can be stimulated throughout the leaf by virus infection and exogenous salicylate. Isozymes AtICS1 and AtICS2 can be successful in competing for chorismate in vivo 747030 5.4.4.2 physiological function isozymes AtICS1 and AtICS2 can be successful in competing for chorismate in vivo 747030 5.4.4.2 physiological function mycobactins are small-molecule iron chelators (siderophores) produced by Mycobacterium tuberculosis (Mtb) for iron mobilization. Siderophores are small-molecule iron chelators that scavenge iron from host tissues and uptake of heme through a specialized heme receptor followed by heme degradation to release the iron. The bifunctional salicylate synthase MbtI catalyzes the first step of mycobactin biosynthesis through the conversion of the primary metabolite chorismate into salicylic acid via isochorismate 748448 5.4.4.2 physiological function Populus ICS primarily functions in phylloquinone biosynthesis 706530 5.4.4.2 physiological function the enzyme is essential for the biosynthesis of the siderophore bacillibactin by the pathogenic bacterium -, 726636 5.4.4.2 physiological function the enzyme is involved in the biosynthesis of pyochelin. Chorismate-utilizing enzymes (CUE) such as chorismate mutase, anthranilate synthase, chorismate pyruvate-lyase, 4-amino-4-deoxychorismate synthase, isochorismate synthase and salicylate synthase are responsible for converting chorismate into various products necessary for the survival of bacteria 747617 5.4.4.2 physiological function the enzyme is involved in the biosynthesis of the siderophore mycobactin. Chorismate-utilizing enzymes (CUE) such as chorismate mutase, anthranilate synthase, chorismate pyruvate-lyase, 4-amino-4-deoxychorismate synthase, isochorismate synthase and salicylate synthase are responsible for converting chorismate into various products necessary for the survival of bacteria -, 747617 5.4.4.2 physiological function the enzyme is involved in the biosynthesis of the siderophore yersiniabactin. Chorismate-utilizing enzymes (CUE) such as chorismate mutase, anthranilate synthase, chorismate pyruvate-lyase, 4-amino-4-deoxychorismate synthase, isochorismate synthase and salicylate synthase are responsible for converting chorismate into various products necessary for the survival of bacteria 747617 5.4.4.2 physiological function the enzyme is required for the appropriate hypersensitive disease defence response. It also takes part in the synthesis of phylloquinone, which is incorporated into photosystem I and is an important component of photosynthetic electron transport in plants role of ICS1 in regulation of state transition. Role of ICS1 in integration of the chloroplast ultrastructure, the redox status of the plastoquinone pool, and organization of the photosystems, which all are important for optimal immune defence and light acclimatory responses -, 728058