No thing really outstanding, but it is nice you can do this in python.

"".join([dict(zip('ACGTacgt','TGCAtgca')) for c in DNASeq[::-1]])

The “dict” probably be created too many times in this form. The two lines version below will be much faster.

m = dict(zip('ACGTacgt','TGCAtgca'))
rcDNASeq="".join([m for c in DNASeq[::-1]])