Actually it is easier to spell with the amino acid alphabet.
In protein gene sequences, three DNA bases code for an amino acid (a codon). There are 4^3 or 64 codons that code for the amino acids and a stop codon. Amino acids can have up to six codons or as few as one.
The amino acids(the building blocks of proteins for those in Rio Linda) all have a one letter abbreviation (alanine=A, Methionine=M, etc). One biotech company, to guard against other companies stealing their work, put a DNA sequence into a gene they introduced into an animal (may have been a rat-I don’t remember). The DNA sequence was in the intron of the gene they introduced.
(Introns are portions of the gene that are spliced out when the gene is transcribed into RNA which is then used to produce proteins.)
When the DNA sequence of the intron was decoded to the one letter amino acid sequence, it spelled out the company’s name. They could check this if they suspected someone had stolen their product.
I hate to break it to you, but they didn’t spell using the four letter alphabet, what they did was utilize DNA to produce amino acids in a certain sequence. That’s not spelling with DNA, that’s spelling with the letters that have been artificially assigned to each amino acid.