Reagents and methods used in deprotection of 3'-O-amino polynucleotides
This disclosure relates to an enzymatic method of synthesizing a polynucleotide, comprising a deprotecting step which uses as a deprotecting agent a specific phosphonate compound. It also pertains to a method for deprotecting 3′-O-amino elongated fragments of a polynucleotide in an enzymatic method of synthesizing a polynucleotide, comprising contacting the elongated fragments with this phosphonate compound. This disclosure further relates to a kit for synthesizing a polynucleotide comprising one or more vials of synthesis reagents, at least one of which contains an effective amount of a phosphonate compound and to a specific method for preparing said phosphonate compound.
1. A method of synthesizing a polynucleotide, the method comprising the steps of:
(a) providing initiators which are polynucleotides having each a free 3′-hydroxyl;
(b) repeating in a reaction mixture, until the polynucleotide is formed, cycles of:
(i) contacting under elongation conditions the initiators or elongated fragments having free 3′-hydroxyls with a 3′-O—NH 2 nucleoside triphosphate and a polymerase, so that the initiators or elongated fragments are elongated by incorporation of a 3′-O-amino nucleoside triphosphate to form 3′-O-amino elongated fragments, and
(ii) deprotecting the elongated fragments to form elongated fragments having free 3′-hydroxyls;
wherein the deprotecting is performed by contacting the elongated fragments with an effective amount of at least one phosphonate compound, wherein at least one phosphonate compound is:
2. The method of claim 1 , wherein said effective amount is provided by a concentration of said phosphonate compound in the range of from about 0.1 to about 500 mM, optionally about 0.1 to about 100 mM or about 0.1 to about 200 mM, in an aqueous solution buffered at a pH of from about 4 to about 8, optionally from about 5 to about 7.
3. The method of claim 2 , wherein the aqueous solution comprises at least one inorganic salt of a divalent metal.
4. The method of claim 3 wherein the divalent metal is selected from the group consisting of magnesium, calcium, zinc, and copper, optionally wherein the at least one inorganic salt is magnesium sulfate.
5. The method of claim 1 , wherein the polymerase is a template-independent polymerase.
6. The method of claim 5 , wherein the template-independent polymerase is Terminal Deoxynucleotidyl Transferase (TdT).
7. The method of claim 5 , wherein the method is an enzymatic DNA synthesis.
8. The method of claim 5 , wherein the method is an enzymatic RNA synthesis.
9. The method of claim 1 , wherein the polymerase is a template-dependent polymerase.
10. The method of claim 9 , wherein the method is sequencing DNA.
11. The method of claim 10 , wherein the method is sequencing-by-synthesis (SBS) or sequencing-by-binding (SBB).
12. The method of claim 11 , wherein the method is sequencing-by-synthesis comprising the steps of:
(a) providing initiators which are polynucleotides having each a free 3′-hydroxyl;
(b) repeating in a reaction mixture, until the polynucleotide is formed, cycles of:
(i) contacting under elongation conditions the initiators or elongated fragments having free 3′-hydroxyls with a fluorescently labelled 3′-O—NH 2 nucleotide and a polymerase, so that the initiators or elongated fragments are elongated by incorporation of a fluorescently labelled 3′-O-amino nucleotide to form 3′-O-amino elongated fragments,
(ii) washing away excess of non-incorporated nucleotides,
(iii) reading the fluorescence signal to know the nucleotide incorporated,
(iv) removing the fluorescent label and using the at least one phosphonate compound to remove the 3′-O-amino group to form elongated fragments having free 3′-hydroxyls, and
(v) repeating steps (i) to (iv) until the end of sequencing.
13. The method of claim 11 , wherein the method is sequencing-by-binding comprising the steps of:
(a) providing initiators which are polynucleotides having each a free 3′-hydroxyl; and,
(b) repeating in a reaction mixture, until the polynucleotide is formed, cycles of:
(i) contacting under elongation conditions the initiators or elongated fragments having free 3′-hydroxyls with a 3′-O—NH 2 nucleotide and a polymerase, so that the initiators or elongated fragments are elongated by incorporation of 3′-O-amino nucleotide to form 3′-O-amino elongated fragments,
(ii) contacting under elongation conditions the 3′-O-amino elongated fragments with a fluorescently labelled nucleotide and a polymerase, so that the fluorescently labelled nucleotide is bound in the active site of the polymerase,
(iii) washing away unbound fluorescently labelled nucleotides,
(iv) reading the fluorescence signal to know the nucleotides bound in the active site,
(v) washing away the bound nucleotides,
(vi) deprotecting the 3′-O—NH 2 polynucleotide with the at least one phosphonate compound, and
(vii) repeating steps (i) to (vi) until the end of sequencing.