Methods for sequencing a biomolecule by detecting relative positions of hybridized probes
A sequencing method is presented in which a biomolecule is hybridized with a specially chosen pool of different probes of known sequence which can be electrically distinguished. The different probe types are tagged such that they can be distinguished from each other in a Hybridization Assisted Nanopore Sequencing (HANS) detection system, and their relative positions on the biomolecule can be determined as the biomolecule passes through a pore or channel. The methods eliminate, resolve, or greatly reduce ambiguities encountered in previous sequencing methods.
1. A method for determining a sequence of a biomolecule, the method comprising the steps of:
(a) identifying a spectrum of k-mer probes that represent a plurality of substrings of a sequence string s of the biomolecule;
(b) arranging the substrings to form a plurality of candidate superstrings each containing all the substrings in step (a), wherein each candidate superstring has a length corresponding to the shortest possible arrangement of all the substrings;
(c) identifying an ambiguity in the ordering of two or more branches common to the candidate superstrings and identifying a plurality of k-mer probes corresponding to the substrings along each of the two or more branches;
(d) for each k-mer probe identified in step (c), hybridizing the biomolecule with the k-mer probe and obtaining an approximate measure of absolute position of the k-mer probe along the biomolecule;
(e) determining a relative order of the two or more branches by, for each branch, obtaining an average of the measures of absolute position of each k-mer probe identified in step (c) that are in the branch, and ordering the two or more branches according to the average absolute position measures identified for each branch, thereby identifying the sequence string s of the biomolecule.
2. The method of claim 1 , wherein steps (a) and (d) are performed simultaneously.
3. The method of claim 1 , wherein steps (a) and (d) are performed using HANS.
4. The method of claim 1 , wherein step (a) is performed using SBH.
5. The method of claim 1 , wherein step (d) comprises monitoring an electrical signal across a fluidic channel or pore or within a fluidic volume of a channel or pore as the hybridized biomolecule translocates therethrough, the electrical signal being indicative of hybridized portions of the biomolecule and non-hybridized portions of the biomolecule.
6. The method of claim 1 , wherein the spectrum of k-mer probes represents a complete set of substrings of the sequence strings.