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Eran Pichersky - One of the best experts on this subject based on the ideXlab platform.
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identification of white campion silene latifolia guaiacol o methyltransferase involved in the biosynthesis of veratrole a key volatile for pollinator attraction
BMC Plant Biology, 2012Co-Authors: Tariq A Akhtar, Alok Gupta, Eran PicherskyAbstract:Background: Silene latifolia and its pollinator, the noctuid moth Hadena bicruris, represent an open nursery pollination system wherein floral volatiles, especially veratrole (1, 2-dimethoxybenzene), lilac aldehydes, and phenylacetaldehyde are of key importance for floral signaling. Despite the important role of floral scent in ensuring reproductive success in S. latifolia, the molecular basis of scent biosynthesis in this species has not yet been investigated. Results: We isolated two full-length cDNAs from S. latifolia that show similarity to rose orcinol O-methyltransferase. Biochemical analysis showed that both S. latifolia guaiacol O-methyltransferase1 (SlGOMT1 )& S. latifolia guaiacol O-methyltransferase2 (SlGOMT2) encode proteins that catalyze the methylation of guaiacol to form veratrole. A large Km value difference between SlGOMT1 (~10 μM) and SlGOMT2 (~501 μM) resulted that SlGOMT1 is 31-fold more catalytically efficient than SlGOMT2. qRT-PCR expression analysis showed that the SlGOMT genes are specifically expressed in flowers and male S. latifolia flowers had 3- to 4-folds higher level of GOMT gene transcripts than female flower tissues. Two related cDNAs, S. dioica O-methyltransferase1 (SdOMT1) and S. dioica O-methyltransferase2 (SdOMT2), were also obtained from the sister species Silene dioica, but the proteins they encode did not methylate guaiacol, consistent with the lack of veratrole emission in the flowers of this species. Our evolutionary analysis uncovered that SlGOMT1 and SlGOMT2 genes evolved under positive selection, whereas SdOMT1 and SdOMT2 genes show no evidence for selection. Conclusions: Altogether, we report the identification and functional characterization of the gene, SlGOMT1 that efficiently catalyzes veratrole formation, whereas another copy of this gene with only one amino acid difference, SlGOMT2 was found to be less efficient for veratrole synthesis in S. latifolia.
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identification of white campion silene latifolia guaiacol o methyltransferase involved in the biosynthesis of veratrole a key volatile for pollinator attraction
BMC Plant Biology, 2012Co-Authors: Tariq A Akhtar, Alok Gupta, Eran PicherskyAbstract:Silene latifolia and its pollinator, the noctuid moth Hadena bicruris, represent an open nursery pollination system wherein floral volatiles, especially veratrole (1, 2-dimethoxybenzene), lilac aldehydes, and phenylacetaldehyde are of key importance for floral signaling. Despite the important role of floral scent in ensuring reproductive success in S. latifolia, the molecular basis of scent biosynthesis in this species has not yet been investigated. We isolated two full-length cDNAs from S. latifolia that show similarity to rose orcinol O-methyltransferase. Biochemical analysis showed that both S. latifolia guaiacol O-methyltransferase1 (SlGOMT1) & S. latifolia guaiacol O-methyltransferase2 (SlGOMT2) encode proteins that catalyze the methylation of guaiacol to form veratrole. A large Km value difference between SlGOMT1 (~10 μM) and SlGOMT2 (~501 μM) resulted that SlGOMT1 is 31-fold more catalytically efficient than SlGOMT2. qRT-PCR expression analysis showed that the SlGOMT genes are specifically expressed in flowers and male S. latifolia flowers had 3- to 4-folds higher level of GOMT gene transcripts than female flower tissues. Two related cDNAs, S. dioica O-methyltransferase1 (SdOMT1) and S. dioica O-methyltransferase2 (SdOMT2), were also obtained from the sister species Silene dioica, but the proteins they encode did not methylate guaiacol, consistent with the lack of veratrole emission in the flowers of this species. Our evolutionary analysis uncovered that SlGOMT1 and SlGOMT2 genes evolved under positive selection, whereas SdOMT1 and SdOMT2 genes show no evidence for selection. Altogether, we report the identification and functional characterization of the gene, SlGOMT1 that efficiently catalyzes veratrole formation, whereas another copy of this gene with only one amino acid difference, SlGOMT2 was found to be less efficient for veratrole synthesis in S. latifolia.
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Structural Basis for Substrate Recognition in The Salicylic Acid Carboxyl Methyltransferase Family
The Plant Cell, 2003Co-Authors: Chloe Zubieta, Eran Pichersky, Jeannine R. Ross, Yue Yang, Paul Koscheski, Joseph P. NoelAbstract:Recently, a novel family of Methyltransferases was identified in plants. Some members of this newly discovered and recently characterized methyltransferase family catalyze the formation of small-molecule methyl esters using S-adenosyl-l-Met (SAM) as a methyl donor and carboxylic acid–bearing substrates as methyl acceptors. These enzymes include SAMT (SAM:salicylic acid carboxyl methyltransferase), BAMT (SAM:benzoic acid carboxyl methyltransferase), and JMT (SAM:jasmonic acid carboxyl methyltransferase). Moreover, other members of this family of plant Methyltransferases have been found to catalyze the N-methylation of caffeine precursors. The 3.0-A crystal structure of Clarkia breweri SAMT in complex with the substrate salicylic acid and the demethylated product S-adenosyl-l-homocysteine reveals a protein structure that possesses a helical active site capping domain and a unique dimerization interface. In addition, the chemical determinants responsible for the selection of salicylic acid demonstrate the structural basis for facile variations of substrate selectivity among functionally characterized plant carboxyl-directed and nitrogen-directed Methyltransferases and a growing set of related proteins that have yet to be examined biochemically. Using the three-dimensional structure of SAMT as a guide, we examined the substrate specificity of SAMT by site-directed mutagenesis and activity assays against 12 carboxyl-containing small molecules. Moreover, the utility of structural information for the functional characterization of this large family of plant Methyltransferases was demonstrated by the discovery of an Arabidopsis methyltransferase that is specific for the carboxyl-bearing phytohormone indole-3-acetic acid.
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Identification of specific residues involved in substrate discrimination in two plant O-Methyltransferases.
Archives of Biochemistry and Biophysics, 1999Co-Authors: Jihong Wang, Eran PicherskyAbstract:Abstract Among the large number of plant O-Methyltransferases that are involved in secondary metabolism, only a few have been enzymatically characterized, and little information is available on the structure of their substrate binding site and the mechanism which determines their substrate specificity and methylation regiospecificity. We have previously reported the isolation of two O-Methyltransferases, S-adenosyl- l -methionine:(iso)eugenol O-methyltransferase (IEMT) and S-adenosyl- l -methionine:caffeic acid O-methyltransferase (COMT) from Clarkia breweri, an annual plant from California. While IEMT and COMT (which methylate eugenol/isoeugenol and caffeic acid/5-hydroxyferulic acid, respectively) share 83% identity at the amino acid level, they have distinct substrate specificity and methylation regiospecificity. We report here that seven amino acids play a critical role in discriminating between eugenol/isoeugenol and caffeic acid/5-hydroxyferulic acid. When these amino acids in IEMT were replaced by the corresponding residues of COMT, the hybrid protein showed activity only with caffeic acid/5-hydroxyferulic acid. Conversely, when these amino acids in COMT were replaced by corresponding IEMT residues, the hybrid protein had activity only with eugenol/isoeugenol. These results provide strong evidence that O-methyltransferase substrate preference could be determined by a few amino acid residues and that new OMTs with different substrate specificity could begin to evolve from an existing OMT by mutation of a few amino acids. Phylogenetic analysis confirms that C. breweri IEMT evolved recently from COMT.
Alok Gupta - One of the best experts on this subject based on the ideXlab platform.
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identification of white campion silene latifolia guaiacol o methyltransferase involved in the biosynthesis of veratrole a key volatile for pollinator attraction
BMC Plant Biology, 2012Co-Authors: Tariq A Akhtar, Alok Gupta, Eran PicherskyAbstract:Background: Silene latifolia and its pollinator, the noctuid moth Hadena bicruris, represent an open nursery pollination system wherein floral volatiles, especially veratrole (1, 2-dimethoxybenzene), lilac aldehydes, and phenylacetaldehyde are of key importance for floral signaling. Despite the important role of floral scent in ensuring reproductive success in S. latifolia, the molecular basis of scent biosynthesis in this species has not yet been investigated. Results: We isolated two full-length cDNAs from S. latifolia that show similarity to rose orcinol O-methyltransferase. Biochemical analysis showed that both S. latifolia guaiacol O-methyltransferase1 (SlGOMT1 )& S. latifolia guaiacol O-methyltransferase2 (SlGOMT2) encode proteins that catalyze the methylation of guaiacol to form veratrole. A large Km value difference between SlGOMT1 (~10 μM) and SlGOMT2 (~501 μM) resulted that SlGOMT1 is 31-fold more catalytically efficient than SlGOMT2. qRT-PCR expression analysis showed that the SlGOMT genes are specifically expressed in flowers and male S. latifolia flowers had 3- to 4-folds higher level of GOMT gene transcripts than female flower tissues. Two related cDNAs, S. dioica O-methyltransferase1 (SdOMT1) and S. dioica O-methyltransferase2 (SdOMT2), were also obtained from the sister species Silene dioica, but the proteins they encode did not methylate guaiacol, consistent with the lack of veratrole emission in the flowers of this species. Our evolutionary analysis uncovered that SlGOMT1 and SlGOMT2 genes evolved under positive selection, whereas SdOMT1 and SdOMT2 genes show no evidence for selection. Conclusions: Altogether, we report the identification and functional characterization of the gene, SlGOMT1 that efficiently catalyzes veratrole formation, whereas another copy of this gene with only one amino acid difference, SlGOMT2 was found to be less efficient for veratrole synthesis in S. latifolia.
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identification of white campion silene latifolia guaiacol o methyltransferase involved in the biosynthesis of veratrole a key volatile for pollinator attraction
BMC Plant Biology, 2012Co-Authors: Tariq A Akhtar, Alok Gupta, Eran PicherskyAbstract:Silene latifolia and its pollinator, the noctuid moth Hadena bicruris, represent an open nursery pollination system wherein floral volatiles, especially veratrole (1, 2-dimethoxybenzene), lilac aldehydes, and phenylacetaldehyde are of key importance for floral signaling. Despite the important role of floral scent in ensuring reproductive success in S. latifolia, the molecular basis of scent biosynthesis in this species has not yet been investigated. We isolated two full-length cDNAs from S. latifolia that show similarity to rose orcinol O-methyltransferase. Biochemical analysis showed that both S. latifolia guaiacol O-methyltransferase1 (SlGOMT1) & S. latifolia guaiacol O-methyltransferase2 (SlGOMT2) encode proteins that catalyze the methylation of guaiacol to form veratrole. A large Km value difference between SlGOMT1 (~10 μM) and SlGOMT2 (~501 μM) resulted that SlGOMT1 is 31-fold more catalytically efficient than SlGOMT2. qRT-PCR expression analysis showed that the SlGOMT genes are specifically expressed in flowers and male S. latifolia flowers had 3- to 4-folds higher level of GOMT gene transcripts than female flower tissues. Two related cDNAs, S. dioica O-methyltransferase1 (SdOMT1) and S. dioica O-methyltransferase2 (SdOMT2), were also obtained from the sister species Silene dioica, but the proteins they encode did not methylate guaiacol, consistent with the lack of veratrole emission in the flowers of this species. Our evolutionary analysis uncovered that SlGOMT1 and SlGOMT2 genes evolved under positive selection, whereas SdOMT1 and SdOMT2 genes show no evidence for selection. Altogether, we report the identification and functional characterization of the gene, SlGOMT1 that efficiently catalyzes veratrole formation, whereas another copy of this gene with only one amino acid difference, SlGOMT2 was found to be less efficient for veratrole synthesis in S. latifolia.
Peter W Laird - One of the best experts on this subject based on the ideXlab platform.
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cpg island hypermethylation in human colorectal tumors is not associated with dna methyltransferase overexpression
Cancer Research, 1999Co-Authors: Cindy A Eads, Kathleen D Danenberg, Kazuyuki Kawakami, Leonard Saltz, Peter V Danenberg, Peter W LairdAbstract:The molecular basis of aberrant hypermethylation of CpG islands observed in a subset of human colorectal tumors is unknown. One potential mechanism is the up-regulation of DNA (cytosine-5)-Methyltransferases. Recently, two new mammalian DNA methyltransferase genes have been identified, which are referred to as DNMT3A and DNMT3B . The encoded proteins differ from the predominant mammalian DNA methyltransferase DNMT1 in that they have a substantially higher ratio of de novo to maintenance methyltransferase activity. We have used a highly quantitative 5′ nuclease fluorogenic reverse transcription-PCR method (TaqMan) to analyze the expression of all three DNA methyltransferase genes in 25 individual colorectal adenocarcinoma specimens and matched normal mucosa samples. In addition, we examined the methylation patterns of four CpG islands [ APC , ESR1 (estrogen receptor), CDKN2A (p16), and MLH1 ] to determine whether individual tumors show a positive correlation between the level of DNA methyltransferase expression and the frequency of CpG island hypermethylation. All three Methyltransferases appear to be up-regulated in tumors when RNA levels are normalized using either ACTB (β-actin) or POLR2A (RNA pol II large subunit), but not when RNA levels are normalized with proliferation-associated genes, such as H4F2 (histone H4) or PCNA . The frequency or extent of CpG island hypermethylation in individual tumors did not correlate with the expression of any of the three DNA Methyltransferases. Our results suggest that deregulation of DNA methyltransferase gene expression does not play a role in establishing tumor-specific abnormal DNA methylation patterns in human colorectal cancer.
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cpg island hypermethylation in human colorectal tumors is not associated with dna methyltransferase overexpression
Cancer Research, 1999Co-Authors: Cindy A Eads, Kathleen D Danenberg, Kazuyuki Kawakami, Peter V Danenberg, Leonard B Saltz, Peter W LairdAbstract:The molecular basis of aberrant hypermethylation of CpG islands observed in a subset of human colorectal tumors is unknown. One potential mechanism is the up-regulation of DNA (cytosine-5)-Methyltransferases. Recently, two new mammalian DNA methyltransferase genes have been identified, which are referred to as DNMT3A and DNMT3B. The encoded proteins differ from the predominant mammalian DNA methyltransferase DNMT1 in that they have a substantially higher ratio of de novo to maintenance methyltransferase activity. We have used a highly quantitative 5' nuclease fluorogenic reverse transcription-PCR method (TaqMan) to analyze the expression of all three DNA methyltransferase genes in 25 individual colorectal adenocarcinoma specimens and matched normal mucosa samples. In addition, we examined the methylation patterns of four CpG islands [APC, ESR1 (estrogen receptor), CDKN2A (p16), and MLH1] to determine whether individual tumors show a positive correlation between the level of DNA methyltransferase expression and the frequency of CpG island hypermethylation. All three Methyltransferases appear to be up-regulated in tumors when RNA levels are normalized using either ACTB (beta-actin) or POLR2A (RNA pol II large subunit), but not when RNA levels are normalized with proliferation-associated genes, such as H4F2 (histone H4) or PCNA. The frequency or extent of CpG island hypermethylation in individual tumors did not correlate with the expression of any of the three DNA Methyltransferases. Our results suggest that deregulation of DNA methyltransferase gene expression does not play a role in establishing tumor-specific abnormal DNA methylation patterns in human colorectal cancer.
Steven E Jacobsen - One of the best experts on this subject based on the ideXlab platform.
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the de novo cytosine methyltransferase drm2 requires intact uba domains and a catalytically mutated paralog drm3 during rna directed dna methylation in arabidopsis thaliana
PLOS Genetics, 2010Co-Authors: Hang-gyeong Chin, Angelique Deleris, Gregory A Horwitz, Krystyna A Kelly, William Wong, Xuehua Zhong, Sriharsa Pradhan, Ian R Henderson, Steven E JacobsenAbstract:Eukaryotic DNA cytosine methylation can be used to transcriptionally silence repetitive sequences, including transposons and retroviruses. This silencing is stable between cell generations as cytosine methylation is maintained epigenetically through DNA replication. The Arabidopsis thaliana Dnmt3 cytosine methyltransferase ortholog DOMAINS REARRANGED METHYLTRANSFERASE2 (DRM2) is required for establishment of small interfering RNA (siRNA) directed DNA methylation. In mammals PIWI proteins and piRNA act in a convergently evolved RNA–directed DNA methylation system that is required to repress transposon expression in the germ line. De novo methylation may also be independent of RNA interference and small RNAs, as in Neurospora crassa. Here we identify a clade of catalytically mutated DRM2 paralogs in flowering plant genomes, which in A.thaliana we term DOMAINS REARRANGED METHYLTRANSFERASE3 (DRM3). Despite being catalytically mutated, DRM3 is required for normal maintenance of non-CG DNA methylation, establishment of RNA–directed DNA methylation triggered by repeat sequences and accumulation of repeat-associated small RNAs. Although the mammalian catalytically inactive Dnmt3L paralogs act in an analogous manner, phylogenetic analysis indicates that the DRM and Dnmt3 protein families diverged independently in plants and animals. We also show by site-directed mutagenesis that both the DRM2 N-terminal UBA domains and C-terminal methyltransferase domain are required for normal RNA–directed DNA methylation, supporting an essential targeting function for the UBA domains. These results suggest that plant and mammalian RNA–directed DNA methylation systems consist of a combination of ancestral and convergent features.
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Methylation of tRNAAsp by the DNA Methyltransferase Homolog Dnmt2
Science (New York N.Y.), 2006Co-Authors: Mary G. Goll, Finn Kirpekar, Steven E Jacobsen, Jeffrey A. Yoder, Keith A. Maggert, Chih-lin Hsieh, Xiaoyu Zhang, Kent G. Golic, Timothy H. BestorAbstract:The sequence and the structure of DNA methyltransferase-2 (Dnmt2) bear close affinities to authentic DNA cytosine Methyltransferases. A combined genetic and biochemical approach revealed that human DNMT2 did not methylate DNA but instead methylated a small RNA; mass spectrometry showed that this RNA is aspartic acid transfer RNA (tRNAAsp) and that DNMT2 specifically methylated cytosine 38 in the anticodon loop. The function of DNMT2 is highly conserved, and human DNMT2 protein restored methylation in vitro to tRNAAsp from Dnmt2-deficient strains of mouse, Arabidopsis thaliana, and Drosophila melanogaster in a manner that was dependent on preexisting patterns of modified nucleosides. Indirect sequence recognition is also a feature of eukaryotic DNA Methyltransferases, which may have arisen from a Dnmt2-like RNA methyltransferase.
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role of cg and non cg methylation in immobilization of transposons in arabidopsis
Current Biology, 2003Co-Authors: Masaomi Kato, Steven E Jacobsen, Judith Bender, Asuka Miura, Tetsuji KakutaniAbstract:Abstract Methylation of cytosine residues in eukaryotic genomes is often associated with repeated sequences including transposons and their derivatives [1, 2]. Methylation has been implicated in control of two potential deleterious effects of these repeats: (1) uncontrolled transcription [2–4], which often disturbs proper expression of nearby host genes [5, 6], and (2) changes in genome structure by transposition and ectopic recombination [2, 7]. Arabidopsis thaliana provides a genetically tractable system to examine these possibilities, since viable mutants in DNA Methyltransferases are available. Arabidopsis MET1 (METHYLTRANSFERASE1, ortholog of mammalian DNA methyltransferase Dnmt1) is necessary for maintaining genomic cytosine methylation at 5′-CG-3′ sites [8, 9]. Arabidopsis additionally methylates non-CG sites using CHROMOMETHYLASE3 (CMT3) [10, 11]. We examined the mobility of endogenous CACTA transposons in met1 , cmt3 , and cmt3-met1 mutants. High-frequency transposition of CACTA elements was detected in cmt3-met1 double mutants. Single mutants in either met1 or cmt3 were much less effective in mobilization, despite significant induction of CACTA transcript accumulation. These results lead us to conclude that CG and non-CG methylation systems redundantly function for immobilization of transposons. Non-CG methylation in plants may have evolved as an additional epigenetic tag dedicated to transposon control. This view is consistent with the recent finding that CMT3 preferentially methylates transposon-related sequences [12].
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Conserved plant genes with similarity to mammalian de novo DNA Methyltransferases.
Proceedings of the National Academy of Sciences of the United States of America, 2000Co-Authors: Xiaofeng Cao, Nathan M. Springer, Michael G. Muszynski, Ronald L. Phillips, Shawn M. Kaeppler, Steven E JacobsenAbstract:DNA methylation plays a critical role in controlling states of gene activity in most eukaryotic organisms, and it is essential for proper growth and development. Patterns of methylation are established by de novo Methyltransferases and maintained by maintenance methyltransferase activities. The Dnmt3 family of de novo DNA Methyltransferases has recently been characterized in animals. Here we describe DNA methyltransferase genes from both Arabidopsis and maize that show a high level of sequence similarity to Dnmt3, suggesting that they encode plant de novo Methyltransferases. Relative to all known eukaryotic Methyltransferases, these plant proteins contain a novel arrangement of the motifs required for DNA methyltransferase catalytic activity. The N termini of these Methyltransferases contain a series of ubiquitin-associated (UBA) domains. UBA domains are found in several ubiquitin pathway proteins and in DNA repair enzymes such as Rad23, and they may be involved in ubiquitin binding. The presence of UBA domains provides a possible link between DNA methylation and ubiquitin/proteasome pathways.
Tariq A Akhtar - One of the best experts on this subject based on the ideXlab platform.
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identification of white campion silene latifolia guaiacol o methyltransferase involved in the biosynthesis of veratrole a key volatile for pollinator attraction
BMC Plant Biology, 2012Co-Authors: Tariq A Akhtar, Alok Gupta, Eran PicherskyAbstract:Background: Silene latifolia and its pollinator, the noctuid moth Hadena bicruris, represent an open nursery pollination system wherein floral volatiles, especially veratrole (1, 2-dimethoxybenzene), lilac aldehydes, and phenylacetaldehyde are of key importance for floral signaling. Despite the important role of floral scent in ensuring reproductive success in S. latifolia, the molecular basis of scent biosynthesis in this species has not yet been investigated. Results: We isolated two full-length cDNAs from S. latifolia that show similarity to rose orcinol O-methyltransferase. Biochemical analysis showed that both S. latifolia guaiacol O-methyltransferase1 (SlGOMT1 )& S. latifolia guaiacol O-methyltransferase2 (SlGOMT2) encode proteins that catalyze the methylation of guaiacol to form veratrole. A large Km value difference between SlGOMT1 (~10 μM) and SlGOMT2 (~501 μM) resulted that SlGOMT1 is 31-fold more catalytically efficient than SlGOMT2. qRT-PCR expression analysis showed that the SlGOMT genes are specifically expressed in flowers and male S. latifolia flowers had 3- to 4-folds higher level of GOMT gene transcripts than female flower tissues. Two related cDNAs, S. dioica O-methyltransferase1 (SdOMT1) and S. dioica O-methyltransferase2 (SdOMT2), were also obtained from the sister species Silene dioica, but the proteins they encode did not methylate guaiacol, consistent with the lack of veratrole emission in the flowers of this species. Our evolutionary analysis uncovered that SlGOMT1 and SlGOMT2 genes evolved under positive selection, whereas SdOMT1 and SdOMT2 genes show no evidence for selection. Conclusions: Altogether, we report the identification and functional characterization of the gene, SlGOMT1 that efficiently catalyzes veratrole formation, whereas another copy of this gene with only one amino acid difference, SlGOMT2 was found to be less efficient for veratrole synthesis in S. latifolia.
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identification of white campion silene latifolia guaiacol o methyltransferase involved in the biosynthesis of veratrole a key volatile for pollinator attraction
BMC Plant Biology, 2012Co-Authors: Tariq A Akhtar, Alok Gupta, Eran PicherskyAbstract:Silene latifolia and its pollinator, the noctuid moth Hadena bicruris, represent an open nursery pollination system wherein floral volatiles, especially veratrole (1, 2-dimethoxybenzene), lilac aldehydes, and phenylacetaldehyde are of key importance for floral signaling. Despite the important role of floral scent in ensuring reproductive success in S. latifolia, the molecular basis of scent biosynthesis in this species has not yet been investigated. We isolated two full-length cDNAs from S. latifolia that show similarity to rose orcinol O-methyltransferase. Biochemical analysis showed that both S. latifolia guaiacol O-methyltransferase1 (SlGOMT1) & S. latifolia guaiacol O-methyltransferase2 (SlGOMT2) encode proteins that catalyze the methylation of guaiacol to form veratrole. A large Km value difference between SlGOMT1 (~10 μM) and SlGOMT2 (~501 μM) resulted that SlGOMT1 is 31-fold more catalytically efficient than SlGOMT2. qRT-PCR expression analysis showed that the SlGOMT genes are specifically expressed in flowers and male S. latifolia flowers had 3- to 4-folds higher level of GOMT gene transcripts than female flower tissues. Two related cDNAs, S. dioica O-methyltransferase1 (SdOMT1) and S. dioica O-methyltransferase2 (SdOMT2), were also obtained from the sister species Silene dioica, but the proteins they encode did not methylate guaiacol, consistent with the lack of veratrole emission in the flowers of this species. Our evolutionary analysis uncovered that SlGOMT1 and SlGOMT2 genes evolved under positive selection, whereas SdOMT1 and SdOMT2 genes show no evidence for selection. Altogether, we report the identification and functional characterization of the gene, SlGOMT1 that efficiently catalyzes veratrole formation, whereas another copy of this gene with only one amino acid difference, SlGOMT2 was found to be less efficient for veratrole synthesis in S. latifolia.
