Structural mechanisms of Tad pilus assembly and its interaction with an RNA virus.
Wang, Y., Theodore, M., Xing, Z., Narsaria, U., Yu, Z., Zeng, L., Zhang, J.(2024) Sci Adv 10: eadl4450-eadl4450
- PubMed: 38701202 
- DOI: https://doi.org/10.1126/sciadv.adl4450
- Primary Citation of Related Structures:  
8U2B, 8UCR, 8UEJ - PubMed Abstract: 
Caulobacter crescentus Tad (tight adherence) pili, part of the type IV pili family, are crucial for mechanosensing, surface adherence, bacteriophage (phage) adsorption, and cell-cycle regulation. Unlike other type IV pilins, Tad pilins lack the typical globular β sheet domain responsible for pilus assembly and phage binding. The mechanisms of Tad pilus assembly and its interaction with phage ΦCb5 have been elusive. Using cryo-electron microscopy, we unveiled the Tad pilus assembly mechanism, featuring a unique network of hydrogen bonds at its core. We then identified the Tad pilus binding to the ΦCb5 maturation protein (Mat) through its β region. Notably, the amino terminus of ΦCb5 Mat is exposed outside the capsid and phage/pilus interface, enabling the attachment of fluorescent and affinity tags. These engineered ΦCb5 virions can be efficiently assembled and purified in Escherichia coli , maintaining infectivity against C. crescentus , which presents promising applications, including RNA delivery and phage display.
Organizational Affiliation: 
Center for Phage Technology, Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA.