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Recombination at Prunus S-locus region SLFL1 gene.

ABSTRACT: In Prunus, the self-incompatibility (S-) locus region is <70 kb. Two genes--the S-RNase, which encodes the functional female recognition component, and the SFB gene, which encodes the pollen recognition component--must co-evolve as a genetic unit to maintain functional incompatibility. Therefore, recombination must be severely repressed at the S-locus. Levels of recombination at genes in the vicinity of the S-locus have not yet been rigorously tested; thus it is unknown whether recombination is also severely repressed at these loci. In this work, we looked at variability levels and patterns at the Prunus spinosa SLFL1 gene, which is physically close to the S-RNase gene. Our results suggest that the recombination level increases near the SLFL1 coding region. These findings are discussed in the context of theoretical models predicting an effect of linked weakly deleterious mutations on the relatedness of S-locus specificities. Moreover, we show that SLFL1 belongs to a gene family of at least five functional genes and that SLFL1 pseudogenes are frequently found in the S-locus region.

SUBMITTER: Vieira J

PROVIDER: S-EPMC2535698 | biostudies-literature | 2008 Sep

REPOSITORIES: biostudies-literature

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Recombination at Prunus S-locus region SLFL1 gene.

Vieira Jorge J Teles Eliana E Santos Raquel A M RA Vieira Cristina P CP

Genetics 20080830 1

In Prunus, the self-incompatibility (S-) locus region is <70 kb. Two genes--the S-RNase, which encodes the functional female recognition component, and the SFB gene, which encodes the pollen recognition component--must co-evolve as a genetic unit to maintain functional incompatibility. Therefore, recombination must be severely repressed at the S-locus. Levels of recombination at genes in the vicinity of the S-locus have not yet been rigorously tested; thus it is unknown whether recombination is ...[more]

PMID: 18757935

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Project description:BackgroundThe co-chaperone Hop [heat shock protein (HSP) organizing protein] has been shown to act as an adaptor for protein folding and maturation, in concert with Hsp70 and Hsp90. The hop gene is of eukaryotic origin. Likewise, the chloroplast elongation factor G (cEF-G) catalyzes the translocation step in chloroplast protein synthesis. The chl-fus gene, which encodes the cEF-G protein, is of plastid origin. Both proteins, Hop and cEF-G, derived from domain duplications. It was demonstrated that the nuclear chl-fus gene locates in opposite orientation to a hop gene in Glycine max. We explored 53 available plant genomes from Chlorophyta to higher plants, to determine whether the chl-fus gene was transferred directly downstream of the primordial hop in the proto-eukaryote host cell. Since both genes came from exon/module duplication events, we wanted to explore the involvement of introns in the early origin and the ensuing evolutionary changes in gene structure.ResultsWe reconstructed the evolutionary history of the two convergent plant genes, on the basis of their gene structure, microsynteny and microcolinearity, from 53 plant nuclear genomes. Despite a high degree (72%) of microcolinearity among vascular plants, our results demonstrate that their adjacency was a product of chromosomal rearrangements. Based on predicted exon--intron structures, we inferred the molecular events giving rise to the current form of genes. Therefore, we propose a simple model of exon/module shuffling by intronic recombinations in which phase-0 introns were essential for domain duplication, and a phase-1 intron for transit peptide recruiting. Finally, we demonstrate a natural susceptibility of the intergenic region to recombine or delete, seriously threatening the integrity of the chl-fus gene for the future.ConclusionsOur results are consistent with the interpretation that the chl-fus gene was transferred from the chloroplast to a chromosome different from that of hop, in the primitive photosynthetic eukaryote, and much later before the appearance of angiosperms, it was recombined downstream of hop. Exon/module shuffling mediated by symmetric intron phases (i.e., phase-0 introns) was essential for gene evolution. The intergenic region is prone to recombine, risking the integrity of both genes.

Project description:Gaucher disease results from an autosomal recessive deficiency of the lysosomal enzyme glucocerebrosidase. The glucocerebrosidase gene is located in a gene-rich region of 1q21 that contains six genes and two pseudogenes within 75 kb. The presence of contiguous, highly homologous pseudogenes for both glucocerebrosidase and metaxin at the locus increases the likelihood of DNA rearrangements in this region. These recombinations can complicate genotyping in patients with Gaucher disease and contribute to the difficulty in interpreting genotype-phenotype correlations in this disorder. In the present study, DNA samples from 240 patients with Gaucher disease were examined using several complementary approaches to identify and characterize recombinant alleles, including direct sequencing, long-template polymerase chain reaction, polymorphic microsatellite repeats, and Southern blots. Among the 480 alleles studied, 59 recombinant alleles were identified, including 34 gene conversions, 18 fusions, and 7 downstream duplications. Twenty-two percent of the patients evaluated had at least one recombinant allele. Twenty-six recombinant alleles were found among 310 alleles from patients with type 1 disease, 18 among 74 alleles from patients with type 2 disease, and 15 among 96 alleles from patients with type 3 disease. Several patients carried two recombinations or mutations on the same allele. Generally, alleles resulting from nonreciprocal recombination (gene conversion) could be distinguished from those arising by reciprocal recombination (crossover and exchange), and the length of the converted sequence was determined. Homozygosity for a recombinant allele was associated with early lethality. Ten different sites of crossover and a shared pentamer motif sequence (CACCA) that could be a hotspot for recombination were identified. These findings contribute to a better understanding of genotype-phenotype relationships in Gaucher disease and may provide insights into the mechanisms of DNA rearrangement in other disorders.

Dataset Information

Recombination at Prunus S-locus region SLFL1 gene.

Publications

Recombination at Prunus S-locus region SLFL1 gene.

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