Structural basis of bacteriophage Ur-lambda infection initiation
Huaxin Yu, Chunyan Wang, Jian Yue, Wangbiao Guo, Ian J. Molineux, Jun Liu
Abstract
Bacteriophages must recognize host receptors and penetrate the host cell envelope to initiate infection. How the classic phage λ initiates infection is not yet understood. Here, we combine cryo–electron microscopy and tomography to visualize infection initiation by Ur-λ, the original λ isolate that uses side fibers to adsorb rapidly to Escherichia coli . We determine the structure of Ur-λ, resolving the full-length central and side fibers, thus providing a structural basis for host recognition. We show that Ur-λ contains six copies of its tape measure protein. We capture intermediates of the tail tip complex during infection initiation, revealing how extensive conformational changes enable adsorption, and visualize the trans-envelope channel required for genome ejection.