The IpaH proteins from Shigella show ubiquitin-ligase activity but lack obvious sequence similarity to HECT- or RING-type ubiquitin ligases. The crystal structure of IpaH3 reveals a two-domain protein with HECT-like catalytic activity mapped to a C-terminal domain of novel fold. These findings suggest that IpaH proteins represent a new family of ubiquitin ligases, a conclusion supported by results from a related study by Tyers et al.
- Yongqun Zhu
- Hongtao Li
- Feng Shao
