The 'shortmer' approach to nucleic acid sequence analysis. I: Computer simulation of sequencing projects to find economical primer sets.

In principle it is most economical to sequence large DNA fragments consecutively ('primer walking'), provided there is an immediate supply of sequencing primers. To solve the problem of primer supply we previously suggested generating a bank of short oligonucleotide primers ('shortmers'). In every sequencing reaction shortmers would have to be selected from this bank that are suitable to hybridize adjacently on the sequencing template. After their ligation the shortmers would form a long, and hence more specific, primer in the subsequent sequencing reaction. In the present study a computer simulation of large sequencing projects revealed a reduced set of approximately 12,000 selected octanucleotides (out of all 65,536) retaining maximum priming flexibility and minimum redundant information on the simulated sequence analyses. Establishing routine protocols for nucleic acid sequencing following the shortmer approach will abolish the tightest bottleneck of the consecutive sequencing route (primer supply) and hence may render this general scheme more attractive than the shotgun sequencing scheme. A twofold (or more) speed-up of genome sequencing projects by the shortmer approach may be assumed.