By submitting a Pull Request, you disavow any rights or claims to any changes submitted to the protein_search project and assign the copyright of those changes to George McCarthy and Giancarlo Fissore.
This is a legal way of saying "If you submit a PR to us, that code becomes ours".
If you cannot or do not want to reassign those rights (your employment contract for your employer may not allow this), you should not submit a PR. Open an issue and someone else can do the work.