A new topology of the HK97-like fold revealed in Bordetella bacteriophage by cryoEM at 3.5 A resolution.

Zhang X, Guo H, Jin L, Czornyj E, Hodes A, Hui WH, Nieh AW, Miller JF, Zhou ZH.

Citation

Zhang X, Guo H, Jin L, Czornyj E, Hodes A, Hui WH, Nieh AW, Miller JF, Zhou ZH. (2013) A new topology of the HK97-like fold revealed in Bordetella bacteriophage by cryoEM at 3.5 A resolution. Elife 2(0):e01299.

Abstract

Bacteriophage BPP-1 infects and kills Bordetella species that cause whooping cough. Its diversity-generating retroelement (DGR) provides a naturally occurring phage-display system, but engineering efforts are hampered without atomic structures. Here, we report a cryo electron microscopy structure of the BPP-1 head at 3.5 Ã?? resolution. Our atomic model shows two of the three protein folds representing major viral lineages: jellyroll for its cement protein (CP) and HK97-like (‘Johnson’) for its major capsid protein (MCP). Strikingly, the fold topology of MCP is permuted non-circularly from the Johnson fold topology previously seen in viral and cellular proteins. We illustrate that the new topology is likely the only feasible alternative of the old topology. Ã?²-sheet augmentation and electrostatic interactions contribute to the formation of non-covalent chainmail in BPP-1, unlike covalent inter-protein linkages of the HK97 chainmail. Despite these complex interactions, the termini of both CP and MCP are ideally positioned for DGR-based phage-display engineering. DOI: http://dx.doi.org/10.7554/eLife.01299.001.