This study investigates the structural mechanism of bacteriophage lambda's interaction with the bacterial receptor, specifically the outer membrane protein LamB. Using high-resolution cryo-electron microscopy (cryo-EM), the researchers determined the structures of the bacteriophage lambda tail complexed with the Shigella sonnei 3070 LamB receptor and the closed central tail fiber. These structures reveal the complex processes that trigger infection, including a significant conformational change in the phage lambda tail tip upon binding to LamB. The study provides detailed insights into the initial stages of lambda phage infection, contributing to the understanding of lambda-bacterial interactions, which has implications for microbiology and therapeutic development. The research highlights the role of the gpl protein in attaching to the cell surface and the specific interactions between the RBD of gpl and LamB, leading to the opening of the tail tip and the formation of a transmembrane channel for DNA injection. The findings also offer insights into the structural alterations in the central tail fiber upon receptor binding, providing a comprehensive view of the structural transitions in lambda phage from the RBD to the HDs upon LamB binding.This study investigates the structural mechanism of bacteriophage lambda's interaction with the bacterial receptor, specifically the outer membrane protein LamB. Using high-resolution cryo-electron microscopy (cryo-EM), the researchers determined the structures of the bacteriophage lambda tail complexed with the Shigella sonnei 3070 LamB receptor and the closed central tail fiber. These structures reveal the complex processes that trigger infection, including a significant conformational change in the phage lambda tail tip upon binding to LamB. The study provides detailed insights into the initial stages of lambda phage infection, contributing to the understanding of lambda-bacterial interactions, which has implications for microbiology and therapeutic development. The research highlights the role of the gpl protein in attaching to the cell surface and the specific interactions between the RBD of gpl and LamB, leading to the opening of the tail tip and the formation of a transmembrane channel for DNA injection. The findings also offer insights into the structural alterations in the central tail fiber upon receptor binding, providing a comprehensive view of the structural transitions in lambda phage from the RBD to the HDs upon LamB binding.