title: DNA sequencing by MALDI-TOF MS using alkali cleavage of RNA/DNA chimeras.
abstract: Approaches developed for sequencing DNA with detection by mass spectrometry use strategies that deviate from the Sanger-type methods. Procedures demonstrated so far used the sequence specificity of RNA endonucleases, as unfortunately equivalent enzymes for DNA do not exist and therefore require transcription of DNA into RNA prior to fragmentation. We have developed a novel, rapid and accurate concept for DNA sequencing using mass spectrometry and RNA/DNA chimeras and applied it to sequence mitochondrial DNA. Our method is based on the preparation of a chimeric RNA/DNA with a DNA polymerase that also incorporates ribonucleotides. Sequencing is carried out with one ribonucleotide (ATP, CTP or GTP) and the other three nucleotides in their deoxyribo-form. The product is treated with alkali, which cleaves 3' of all ribonucleotides to form a terminal 3' phosphate. Conditions have been streamlined so that molecular, biological and alkali cleavage conditions are compatible with matrix-assisted laser desorption/ionization time-of-flight (MALDI) mass spectrometric analysis. Fragment analysis by MALDI MS provides a sequence-specific fingerprint, which allows the identification of differences between a reference and another sequence. Due to the mass profile, the position and kind of the mutation can be assigned. These differences between signatures are indicative of known, unidentified, rare and private mutations. This novel DNA sequencing protocol was applied to sequence the hypervariable region 1 (HV1) of mitochondrial DNA in 22 individuals.
authors.affiliation: Centre National de Génotypage, Bâtiment G2, 2 rue Gaston Crémieux, 91057 Evry Cedex, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Mauger
authors.forename: Keith
authors.initials: K
authors.lastname: Bauer
authors.forename: Cassandra D
authors.initials: CD
authors.lastname: Calloway
authors.forename: Jérémy
authors.initials: J
authors.lastname: Semhoun
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Nishimoto
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Myers
authors.forename: David H
authors.initials: DH
authors.lastname: Gelfand
authors.forename: Ivo G
authors.initials: IG
authors.lastname: Gut
mesh_terms: D004247:DNA / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000737:chemistry; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D003854:Deoxyribonucleotides / Q000378:metabolism; D011110:Polymorphism, Genetic; D012313:RNA / Q000378:metabolism; D012265:Ribonucleotides / Q000378:metabolism; D017422:Sequence Analysis, DNA / Q000379:methods*; D012972:Sodium Hydroxide; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D004272:DNA, Mitochondrial; D003854:Deoxyribonucleotides; D012265:Ribonucleotides; D012972:Sodium Hydroxide; D012313:RNA; D004247:DNA; D004259:DNA-Directed DNA Polymerase