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Polymerase enzyme from 9°n

a polymerase and enzyme technology, applied in the field of molecular biology, can solve the problems of inferior sequencing ladder compared to wild type enzymes, insufficient incorporation rate of modified nucleotides, and difficulty in incorporating modified nucleotides, so as to improve the efficiency of certain dna sequencing methods and improve the incorporation rate of such 3′ substituted nucleotide analogues

Inactive Publication Date: 2020-01-02
QIAGEN SCIENCES LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent is about a method of DNA sequencing using nucleotides with a 3' blocking group to prevent uncontrolled sequencing. The blocking group must be removable to allow for multiple cycles of sequencing. The method also involves using modified nucleotides that have a higher rate of incorporation and enhanced specificity / sensitivity compared to wild-type polymerases. The polymerases used in the patent show increased activity and sensitivity towards bulky nucleotides compared to other polymerases.

Problems solved by technology

Early experiments with DNA polymerases revealed difficulties incorporating modified nucleotides such as dideoxynucleotides (ddNTPs).
However, mutation of Y410 to A or F produced a variant that resulted in an inferior sequencing ladder compared to the wild type enzyme.
Yet, the modifications today still do not show sufficiently high incorporation rates of modified nucleotides (3′OH substituted analogs or having both substitutions on 3′-OH and carrying labels at the base).
This residual modification may interfere with incorporation of subsequent nucleotides by polymerase.

Method used

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  • Polymerase enzyme from 9°n
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  • Polymerase enzyme from 9°n

Examples

Experimental program
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Effect test

example 1

Synthesis of 3′-O-(methylthiomethyl)-5′-O-(tert-butyldimethylsilyl)-2′-deoxythymidine (2)

[0121]5′-O-(tert-butyldimethylsilyl)-2′-deoxythymidine (1) (2.0 g, 5.6 mmol) was dissolved in a mixture consisting of DMSO (10.5 mL), acetic acid (4.8 mL), and acetic anhydride (15.4 mL) in a 250 mL round bottom flask, and stirred for 48 hours at room temperature. The mixture was then quenched by adding saturated K2CO3 solution until evolution of gaseous CO2 was stopped. The mixture was then extracted with EtOAc (3×100 mL) using a separating funnel. The combined organic extract was then washed with a saturated solution of NaHCO3 (2×150 mL) in a partitioning funnel, and the organic layer was dried over Na2SO4. The organic part was concentrated by rotary evaporation. The reaction mixture was finally purified by silica gel column chromatography.

example 2

Synthesis of 3′-O-(ethyldithiomethyl)-2′-deoxythymidine (4)

[0122]Compound 2 (1.75 g, 4.08 mmol), dried overnight under high vacuum, dissolved in 20 mL dry CH2CI2 was added with EtsN (0.54 mL, 3.87 mmol) and 5.0 g molecular sieve-3A, and stirred for 30 min under Ar atmosphere. The reaction flask was then placed on an ice-bath to bring the temperature to sub-zero, and slowly added with 1.8 eq 1M SO2CI2 in CH2CI2 (1.8 mL) and stirred at the same temperature for 1.0 hour. Then the ice-bath was removed to bring the flask to room temperature, and added with a solution of potassium thiotosylate (1.5 g) in 4 mL dry DMF and stirred for 0.5 hour at room temperature.

[0123]Then 2 eq EtSH (0.6 mL) was added and stirred additional 40 min. The mixture was then diluted with 50 mL CH2CI2 and filtered through celite-S in a funnel. The sample was washed with adequate amount of CH2CI2 to make sure that the product was filtered out. The CH2CI2 extract was then concentrated and purified by chromatography...

example 3

Synthesis of the triphosphate of 3′-O-(ethyldithiomethyl)-2′-deoxythymidine (5)

[0124]In a 25 mL flask, compound 4 (0.268 g, 0.769 mmol) was added with proton sponge (210 mg), equipped with rubber septum. The sample was dried under high vacuum for overnight. The material was then dissolved in 2.6 mL (MeO)3P0 under argon atmosphere. The flask, equipped with Ar-gas supply, was then placed on an ice-bath, stirred to bring the temperature to sub-zero. Then 1.5 equivalents of POCI3 was added at once by a syringe and stirred at the same temperature for 2 hours under Argon atmosphere. Then the ice-bath was removed and a mixture consisting of tributylammonium-pyrophosphate (1.6 g) and Bu3N (1.45 mL) in dry DMF (6 mL) was prepared. The entire mixture was added at once and stirred for 10 min. The reaction mixture was then diluted with TEAB buffer (30 mL, 100 mM) and stirred for additional 3 hours at room temperature. The crude product was concentrated by rotary evaporation, and purified by CI ...

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Abstract

The present invention relates to a polymerase enzyme from 9°N with improved ability to incorporate reversibly terminating nucleotides. The enzyme comprising mutations in the motif A region. The invention also relates to methods of using such enzymes as well as a kit with such polymerases.

Description

FIELD OF THE INVENTION[0001]The present invention is in the field of molecular biology, in particular in the field of enzymes and more particular in the field of polymerases. It is also in the field of nucleic acid sequencing.BACKGROUND[0002]The invention relates to polymerase enzymes, in particular modified DNA polymerases which show improved incorporation of modified nucleotides compared to a control polymerase. Also included in the present invention are methods of using the modified polymerases for DNA sequencing, in particular next generation sequencing.[0003]Three main super families of DNA polymerase exist, based upon their amino acid similarity to E. coli DNA polymerases I, II and III. They are called family A, B and C polymerases respectively. Whilst crystallographic analysis of Family A and B polymerases reveals a common structural core for the nucleotide binding site, sequence motifs that are well conserved within families are only weakly conserved between families, and th...

Claims

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Application Information

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IPC IPC(8): C12N9/12C12Q1/6869C12Q1/6844
CPCC12N9/1252C12Q1/6869C12Q1/6844C12Y207/07007C12Q2521/101C12Q2525/101C12Q2525/113
Inventor OLEJNIK, JERZYDELUCIA, ANGELA
Owner QIAGEN SCIENCES LLC