Until recently I thought that there was a clean distinction between polypeptides and oligonucleotides, but apparently there are recent studies of therapeutic compounds that could be described as "chimeras", "hybrids", or "conjugates" of nucleic acids and peptides. Usually, these are linked by a synthetic spacer group.
This got me wondering if there are hybrids of polypeptides with DNA or RNA that occur naturally. I know about aminoacyl-RNA, but my understanding is that this is only a single amino acid covalently bonded to RNA.
So I want to ask what these hybrids might look like in nature, if they do exist. (For example, would an amino acid residue be directly attached to (deoxy)ribose, or somehow connected with the phosphate?)
My attempts at searching keep turning up peptide nucleic acids, which are interesting in themselves, but are fully synthetic and thus not what I am asking about.
Pointers to the literature would be highly appreciated (especially survey articles).