The biomolecule that is part of the structure of both ATP nucleotides and nucleic acids is phosphate.

Here's why:

* ATP (Adenosine Triphosphate): ATP is a nucleotide consisting of adenine (a nitrogenous base), ribose (a sugar), and three phosphate groups.

* Nucleic Acids (DNA and RNA): Nucleic acids are polymers made up of nucleotides. Each nucleotide has a phosphate group, a sugar (deoxyribose in DNA and ribose in RNA), and a nitrogenous base (adenine, guanine, cytosine, thymine in DNA; adenine, guanine, cytosine, uracil in RNA).

Therefore, phosphate is the common building block found in both ATP and nucleic acids.