CRISPR: An enzyme taken from Leptotrichia shahii can bind to and cut ss messenger RNA.

A new version of the gene-editing tool CRISPR can target and cut RNA

also see:

http://www.the-scientist.com/?articles.view/articleNo/46234/title/RNA-Targeting-CRISPR/

and

http://www.the-scientist.com/?articles.view/articleNo/45354/title/Dial-It-Up--Dial-It-Down/