Figure 2.

Sequence features of the new split-inteins. Multiple sequence alignment of N-terminal (A) and C-terminal (B) halves of full-length split-inteins. Conserved motifs of the HINT protein-splicing family are boxed and labeled, and active-site residues are marked with an asterisk. The sequence alignment was refined based on structural modeling with the cyanobacterial DnaE split-intein as a template (PDB code: 1ZD7). Sequences are named after their protein host. (C) Electrostatic characteristics of full-length split-inteins. The number of salt-bridges was calculated from the modeled tertiary structures, and is indicated together with the local charges of the two interacting beta-strands of the intein-halves. (D) Illustration of salt-bridges at the interaction interface between the N-terminal (blue) and C-terminal (red) halves, in the modeled structure of gp41-1. The two longest anti-parallel beta-strands of the intein molecule are shown in cartoon representation.