Design and evolution of artificial M13 coat proteins

Using simple design and selective pressure, we have evolved an artificial M 13 bacteriophage coat protein. M13 coat proteins first reside in the bacter ial inner membrane and subsequently surround the DNA core of the assembled virus. The artificial coat protein (ACP) was designed and evolved to mimic both functions of the natural M13 coat proteins, but with an inverted orien tation. ACP is a non-functional coat protein because it is not required for the production of phage particles. Instead, it incorporates into a phage c oat which still requires all the natural coat proteins for structural integ rity. In contrast with other M13 coat proteins, which can display polypepti des as aminoterminal fusions, ACP permits the carboxy-terminal display of l arge polypeptides. The results suggest that viruses can co-opt host membran e proteins to acquire new coat proteins and thus new functions. In particul ar, M13 bacteriophage can be engineered for new functions, such as carboxy- terminal phage display. (C) 2000 Academic Press.