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A new MALDI-TOF based mini-sequencing assay for genotyping of SNPS.

ABSTRACT: A new MALDI-TOF based mini-sequencing assay termed VSET was developed for genotyping of SNPs. In this assay, specific fragments of genomic DNA containing the SNP site(s) are first amplified, followed by mini-sequencing in the presence of three ddNTPs and the fourth nucleotide in the deoxy form. In this way, the primer is extended by only one base from one allele, while it is typically extended by two bases from another allele. The products are then analyzed using MALDI-TOF mass spectrometry. The genotype of the SNP site is identified based on the number of nucleotides added. This assay has been examined using both synthetic and genomic DNA samples. In addition, multiplexed assays were successfully performed to genotype four SNP sites in a single tube. The main aspect of this assay is that it can overcome the key problems associated with the currently used mini-sequencing methods. First, it significantly reduces the stringent high-resolution and extensive desalting requirements that are essential to the pinpoint assay. Second, it avoids the long extension problem associated with the PROBE assay.

SUBMITTER: Sun X

PROVIDER: S-EPMC102753 | biostudies-literature | 2000 Jun

REPOSITORIES: biostudies-literature

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A new MALDI-TOF based mini-sequencing assay for genotyping of SNPS.

Sun X X Ding H H Hung K K Guo B B

Nucleic acids research 20000601 12

A new MALDI-TOF based mini-sequencing assay termed VSET was developed for genotyping of SNPs. In this assay, specific fragments of genomic DNA containing the SNP site(s) are first amplified, followed by mini-sequencing in the presence of three ddNTPs and the fourth nucleotide in the deoxy form. In this way, the primer is extended by only one base from one allele, while it is typically extended by two bases from another allele. The products are then analyzed using MALDI-TOF mass spectrometry. The ...[more]

PMID: 10871391

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Project description:We describe a new method for encoded synthesis, efficient on-resin screening, and rapid unambiguous sequencing of combinatorial peptide libraries. An improved binary tag system for encoding peptide libraries during synthesis was designed to facilitate unequivocal assignment of isobaric residues by MALDI-TOF MS analysis. The improved method for encoded library synthesis was combined with a new versatile on-resin screening strategy that permitted multiple stages and types of screening to be employed successively on one library under mild conditions. The new method facilitated a combinatorial study of transglutaminase (TGase) enzyme substrate peptides, revealing new details of the effect of amino acid composition on TGase substrates. The approach was first demonstrated for an encoded library (130,321 compounds) of lysine pentapeptide substrates of TGase, synthesized using the "split-mix" method. The library was reacted on-resin with TGase enzyme and a soluble desthiobiotin labeled glutamine substrate. Initial screening was performed by adsorbing streptavidin-coated magnetic microparticles onto library beads, followed by magnetic separation. The differential binding affinities of desthiobiotin and biotin for streptavidin were exploited to release the magnetic microparticles and regenerate the desthiobiotin-labeled resin beads for further screening by flow-cytometry-based automated bead sorting, resulting in 345 beads that were sequenced by MALDI-TOF MS analysis. A second library consisted of encoded glutamine hexapeptide substrates, which was reacted on-resin with TGase enzyme and a soluble desthiobiotin-labeled cadaverine. Two-stage screening identified 267 glutamine peptides as TGase-reactive, of which 21 were further analyzed by solution-phase enzyme kinetics. Kinetic results indicated that the peptide PQQQYV from the library has a 68-fold greater substrate specificity than the best known glutamine substrate QQIV. The new encoding and screening strategies described here are expected to be broadly applicable to synthesis and screening of combinatorial peptide libraries in the future.

Dataset Information

A new MALDI-TOF based mini-sequencing assay for genotyping of SNPS.

Publications

A new MALDI-TOF based mini-sequencing assay for genotyping of SNPS.

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