Gene_locus Report for: arath-SCPL34

The Arabidopsis (Arabidopsis thaliana) genome encodes a family of 51 proteins that are homologous to known serine carboxypeptidases. Based on their sequences, these serine carboxypeptidase-like (SCPL) proteins can be divided into several major clades. The first group consists of 21 proteins which, despite the function implied by their annotation, includes two that have been shown to function as acyltransferases in plant secondary metabolism: sinapoylglucose:malate sinapoyltransferase and sinapoylglucose:choline sinapoyltransferase. A second group comprises 25 SCPL proteins whose biochemical functions have not been clearly defined. Genes encoding representatives from both of these clades can be found in many plants, but have not yet been identified in other phyla. In contrast, the remaining SCPL proteins include five members that are similar to serine carboxypeptidases from a variety of organisms, including fungi and animals. Reverse transcription PCR results suggest that some SCPL genes are expressed in a highly tissue-specific fashion, whereas others are transcribed in a wide range of tissue types. Taken together, these data suggest that the Arabidopsis SCPL gene family encodes a diverse group of enzymes whose functions are likely to extend beyond protein degradation and processing to include activities such as the production of secondary metabolites.

The genome of the model plant Arabidopsis thaliana has been sequenced by an international collaboration, The Arabidopsis Genome Initiative. Here we report the complete sequence of chromosome 5. This chromosome is 26 megabases long; it is the second largest Arabidopsis chromosome and represents 21% of the sequenced regions of the genome. The sequence of chromosomes 2 and 4 have been reported previously and that of chromosomes 1 and 3, together with an analysis of the complete genome sequence, are reported in this issue. Analysis of the sequence of chromosome 5 yields further insights into centromere structure and the sequence determinants of heterochromatin condensation. The 5,874 genes encoded on chromosome 5 reveal several new functions in plants, and the patterns of gene organization provide insights into the mechanisms and extent of genome evolution in plants.

A total of 17 P1 and TAC clones each containing a marker(s) specifically mapped on chromosome 5 were isolated from P1 and TAC libraries of the Arabidopsis thaliana Columbia genome, and their nucleotide sequences were determined according to the shot gun-based strategy and precisely located on the physical map of chromosome 5. The total length of the clones sequenced in this study was 1,191,918 bp. As we have previously reported the sequence of 2,662,078 bp by analysis of 33 P1 clones, the total length of the sequences of chromosome 5 determined so far is now 3,853,996 bp. The sequences determined in this study were subjected to similarity search against protein and EST databases and analysis with computer programs for gene modeling, and a total of 310 potential protein-coding genes and/or gene segments with known or predicted functions were identified. The positions of exons which do not show apparent similarity to known genes were also predicted by computer-aided analysis. An average density of the assigned genes and/or gene segments was 1 gene/3,845 bp. Introns were identified in 78% of the potential protein genes, and the average number per gene and the average length of the introns were 3.7 and 185 bp, respectively. The numbers of the Arabidopsis ESTs matched to each of the predicted genes have been counted to monitor the transcription level. The sequence data and gene information are available on the World Wide Web database KAOS (Kazusa Arabidopsis data Opening Site) at http://www.kazusa.or.jp/arabi/.

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.

The Arabidopsis (Arabidopsis thaliana) genome encodes a family of 51 proteins that are homologous to known serine carboxypeptidases. Based on their sequences, these serine carboxypeptidase-like (SCPL) proteins can be divided into several major clades. The first group consists of 21 proteins which, despite the function implied by their annotation, includes two that have been shown to function as acyltransferases in plant secondary metabolism: sinapoylglucose:malate sinapoyltransferase and sinapoylglucose:choline sinapoyltransferase. A second group comprises 25 SCPL proteins whose biochemical functions have not been clearly defined. Genes encoding representatives from both of these clades can be found in many plants, but have not yet been identified in other phyla. In contrast, the remaining SCPL proteins include five members that are similar to serine carboxypeptidases from a variety of organisms, including fungi and animals. Reverse transcription PCR results suggest that some SCPL genes are expressed in a highly tissue-specific fashion, whereas others are transcribed in a wide range of tissue types. Taken together, these data suggest that the Arabidopsis SCPL gene family encodes a diverse group of enzymes whose functions are likely to extend beyond protein degradation and processing to include activities such as the production of secondary metabolites.

The genome of the model plant Arabidopsis thaliana has been sequenced by an international collaboration, The Arabidopsis Genome Initiative. Here we report the complete sequence of chromosome 5. This chromosome is 26 megabases long; it is the second largest Arabidopsis chromosome and represents 21% of the sequenced regions of the genome. The sequence of chromosomes 2 and 4 have been reported previously and that of chromosomes 1 and 3, together with an analysis of the complete genome sequence, are reported in this issue. Analysis of the sequence of chromosome 5 yields further insights into centromere structure and the sequence determinants of heterochromatin condensation. The 5,874 genes encoded on chromosome 5 reveal several new functions in plants, and the patterns of gene organization provide insights into the mechanisms and extent of genome evolution in plants.

A total of 17 P1 and TAC clones each containing a marker(s) specifically mapped on chromosome 5 were isolated from P1 and TAC libraries of the Arabidopsis thaliana Columbia genome, and their nucleotide sequences were determined according to the shot gun-based strategy and precisely located on the physical map of chromosome 5. The total length of the clones sequenced in this study was 1,191,918 bp. As we have previously reported the sequence of 2,662,078 bp by analysis of 33 P1 clones, the total length of the sequences of chromosome 5 determined so far is now 3,853,996 bp. The sequences determined in this study were subjected to similarity search against protein and EST databases and analysis with computer programs for gene modeling, and a total of 310 potential protein-coding genes and/or gene segments with known or predicted functions were identified. The positions of exons which do not show apparent similarity to known genes were also predicted by computer-aided analysis. An average density of the assigned genes and/or gene segments was 1 gene/3,845 bp. Introns were identified in 78% of the potential protein genes, and the average number per gene and the average length of the introns were 3.7 and 185 bp, respectively. The numbers of the Arabidopsis ESTs matched to each of the predicted genes have been counted to monitor the transcription level. The sequence data and gene information are available on the World Wide Web database KAOS (Kazusa Arabidopsis data Opening Site) at http://www.kazusa.or.jp/arabi/.