Contents

19 September 2014
Vol 345, Issue 6203

About The Cover

Cover image expansion

COVER Artist's impression of how a bacterial immune complex, called Cascade (foreground structure), from the CRISPR-Cas system recognizes invading DNA (red-blue-black strand) from a bacteriophage. Cascade, a complex of 11 proteins and a guide RNA, uses the sequence of the guide RNA to detect invading DNA. See pages 1452, 1473, and 1479 for a close-up look at Cascade before and after it binds to its target DNA.
Illustration: Valerie Altounian/Science; protein coordinate data supplied by Scott Bailey