Drug-resistant bacteria have caused serious medical problems in recent years, and the need for new antibacterial agents is undisputed. Transglycosylase, a multidomain membrane protein essential for cell wall synthesis, is an excellent target for the development of new antibiotics. Here, we determined the X-ray crystal structure of the bifunctional transglycosylase penicillin-binding protein 1b (PBP1b) from Escherichia coli in complex with its inhibitor moenomycin to 2.16-Å  resolution. In addition to the transglycosylase and transpeptidase domains, our structure provides a complete visualization of this important antibacterial target, and reveals a domain for protein-protein interaction and a transmembrane helix domain essential for substrate binding, enzymatic activity, and membrane orientation.The research was conducted at the NSRRC beamline BL13B1.