The goal of the study is to identify the RNA-protein binding motifs used by the G. kaustauphilus S15 and to understand how specific or general the binding site can be. This data is from an in vitro evolution experiment to find RNA aptamers that bind to the G.kaustophilus ribosomal protein S15. There are 11 rounds in total with high-throughput sequencing from samples of rounds 4, 9, 10, and 11. The random sequence pool is generated by starting with the E. coli S15 mRNA target and randomizing the 30 nucleotides that make up stem 1, with the rest remaining unchanged. By randomizing the RNA-protein binding region, we elucidate the sequence and structure contributions to the RNA-protein binding site. This work more broadly seeks to identify the difficulty of creating an RNA recognized by S15 and understand why the protein recognizes such a diverse set of RNA secondary structures.