Gene_locus Report for: arath-At2g45610

The relationships of sterase- and lipase-like proteins with three signaling molecules (salicylic acid, jasmonic acid, and ethylene) expressed during plantpathogen interactions were studied. We isolated two carboxylesterase (AtCXE) genes, AtCXE8 and AtCXE9, from Arabidopsis thaliana. The AtCXE8 and AtCXE9 proteins possess carboxylesterase motifs (-GXSXG-) and catalytic triads (Ser, Asp, and His). We demonstrated that recombinant AtCXE8 and AtCXE9 proteins have both enzymatic activity and specific activity for p-nitrophenyl butyrate (C4) in vitro. Moreover, the enzymatic activity of recombinant AtCXE8 was twofold higher than that of AtCXE9. To gain a better understanding of the endogenous role of the AtCXE8 gene in Arabidopsis, we identified an enhancer trap T-DNA mutant (AtCXE8_KO) and used it to show that the AtCXE8 gene was induced in response to fungal infection. AtCXE8_KO plants were also more susceptible to infections than wild-type Col-0 plants. Moreover, overexpression of the AtCXE8 gene in transgenic Arabidopsis plants led to enhanced disease resistance against B. cinerea. Taken together, our data indicate that AtCXE8 plays a role in promoting resistance to fungal invasion.

Carboxylesterases hydrolyze esters of short-chain fatty acids and have roles in animals ranging from signal transduction to xenobiotic detoxification. In plants, however, little is known of their roles. We have systematically mined the genome from the model plant Arabidopsis thaliana for carboxylesterase genes and studied their distribution in the genome and expression profile across a range of tissues. Twenty carboxylesterase genes (AtCXE) were identified. The AtCXE family shares conserved sequence motifs and secondary structure characteristics with carboxylesterases and other members of the larger alpha/beta hydrolase fold superfamily of enzymes. Phylogenetic analysis of the AtCXE genes together with other plant carboxylesterases distinguishes seven distinct clades, with an Arabidopsis thaliana gene represented in six of the seven clades. The AtCXE genes are widely distributed across the genome (present in four of five chromosomes), with the exception of three clusters of tandemly duplicated genes. Of the interchromosomal duplication events, two have been mediated through newly identified partial chromosomal duplication events that also include other genes surrounding the AtCXE loci. Eighteen of the 20 AtCXE genes are expressed over a broad range of tissues, while the remaining 2 (unrelated) genes are expressed only in the flowers and siliques. Finally, hypotheses for the functional roles of the AtCXE family members are presented based on the phylogenetic relationships with other plant carboxylesterases of known function, their expression profile, and knowledge of likely esterase substrates found in plants.

Arabidopsis thaliana (Arabidopsis) is unique among plant model organisms in having a small genome (130-140 Mb), excellent physical and genetic maps, and little repetitive DNA. Here we report the sequence of chromosome 2 from the Columbia ecotype in two gap-free assemblies (contigs) of 3.6 and 16 megabases (Mb). The latter represents the longest published stretch of uninterrupted DNA sequence assembled from any organism to date. Chromosome 2 represents 15% of the genome and encodes 4,037 genes, 49% of which have no predicted function. Roughly 250 tandem gene duplications were found in addition to large-scale duplications of about 0.5 and 4.5 Mb between chromosomes 2 and 1 and between chromosomes 2 and 4, respectively. Sequencing of nearly 2 Mb within the genetically defined centromere revealed a low density of recognizable genes, and a high density and diverse range of vestigial and presumably inactive mobile elements. More unexpected is what appears to be a recent insertion of a continuous stretch of 75% of the mitochondrial genome into chromosome 2.

The relationships of sterase- and lipase-like proteins with three signaling molecules (salicylic acid, jasmonic acid, and ethylene) expressed during plantpathogen interactions were studied. We isolated two carboxylesterase (AtCXE) genes, AtCXE8 and AtCXE9, from Arabidopsis thaliana. The AtCXE8 and AtCXE9 proteins possess carboxylesterase motifs (-GXSXG-) and catalytic triads (Ser, Asp, and His). We demonstrated that recombinant AtCXE8 and AtCXE9 proteins have both enzymatic activity and specific activity for p-nitrophenyl butyrate (C4) in vitro. Moreover, the enzymatic activity of recombinant AtCXE8 was twofold higher than that of AtCXE9. To gain a better understanding of the endogenous role of the AtCXE8 gene in Arabidopsis, we identified an enhancer trap T-DNA mutant (AtCXE8_KO) and used it to show that the AtCXE8 gene was induced in response to fungal infection. AtCXE8_KO plants were also more susceptible to infections than wild-type Col-0 plants. Moreover, overexpression of the AtCXE8 gene in transgenic Arabidopsis plants led to enhanced disease resistance against B. cinerea. Taken together, our data indicate that AtCXE8 plays a role in promoting resistance to fungal invasion.

We report the 207-Mb genome sequence of the North American Arabidopsis lyrata strain MN47 based on 8.3x dideoxy sequence coverage. We predict 32,670 genes in this outcrossing species compared to the 27,025 genes in the selfing species Arabidopsis thaliana. The much smaller 125-Mb genome of A. thaliana, which diverged from A. lyrata 10 million years ago, likely constitutes the derived state for the family. We found evidence for DNA loss from large-scale rearrangements, but most of the difference in genome size can be attributed to hundreds of thousands of small deletions, mostly in noncoding DNA and transposons. Analysis of deletions and insertions still segregating in A. thaliana indicates that the process of DNA loss is ongoing, suggesting pervasive selection for a smaller genome. The high-quality reference genome sequence for A. lyrata will be an important resource for functional, evolutionary and ecological studies in the genus Arabidopsis.

Carboxylesterases hydrolyze esters of short-chain fatty acids and have roles in animals ranging from signal transduction to xenobiotic detoxification. In plants, however, little is known of their roles. We have systematically mined the genome from the model plant Arabidopsis thaliana for carboxylesterase genes and studied their distribution in the genome and expression profile across a range of tissues. Twenty carboxylesterase genes (AtCXE) were identified. The AtCXE family shares conserved sequence motifs and secondary structure characteristics with carboxylesterases and other members of the larger alpha/beta hydrolase fold superfamily of enzymes. Phylogenetic analysis of the AtCXE genes together with other plant carboxylesterases distinguishes seven distinct clades, with an Arabidopsis thaliana gene represented in six of the seven clades. The AtCXE genes are widely distributed across the genome (present in four of five chromosomes), with the exception of three clusters of tandemly duplicated genes. Of the interchromosomal duplication events, two have been mediated through newly identified partial chromosomal duplication events that also include other genes surrounding the AtCXE loci. Eighteen of the 20 AtCXE genes are expressed over a broad range of tissues, while the remaining 2 (unrelated) genes are expressed only in the flowers and siliques. Finally, hypotheses for the functional roles of the AtCXE family members are presented based on the phylogenetic relationships with other plant carboxylesterases of known function, their expression profile, and knowledge of likely esterase substrates found in plants.

Arabidopsis thaliana (Arabidopsis) is unique among plant model organisms in having a small genome (130-140 Mb), excellent physical and genetic maps, and little repetitive DNA. Here we report the sequence of chromosome 2 from the Columbia ecotype in two gap-free assemblies (contigs) of 3.6 and 16 megabases (Mb). The latter represents the longest published stretch of uninterrupted DNA sequence assembled from any organism to date. Chromosome 2 represents 15% of the genome and encodes 4,037 genes, 49% of which have no predicted function. Roughly 250 tandem gene duplications were found in addition to large-scale duplications of about 0.5 and 4.5 Mb between chromosomes 2 and 1 and between chromosomes 2 and 4, respectively. Sequencing of nearly 2 Mb within the genetically defined centromere revealed a low density of recognizable genes, and a high density and diverse range of vestigial and presumably inactive mobile elements. More unexpected is what appears to be a recent insertion of a continuous stretch of 75% of the mitochondrial genome into chromosome 2.