A functional interplay between intein and extein sequences in protein splicing compensates for the essential block B histidine.

Inteins remove themselves from a precursor protein by protein splicing. Due to the concomitant structural changes of the host protein, this self-processing reaction has enabled many applications in protein biotechnology and chemical biology. We show that the evolved M86 mutant of the DnaB intein displays a significantly improved tolerance towards non-native amino acids at the N-terminally flanking (-1) extein position compared to the parent intein, in the form of both an artificially -splicing split intein and the -splicing mini-intein.

Ligation of synthetic peptides to proteins using semisynthetic protein trans-splicing.

Protein trans-splicing using split inteins is a powerful and convenient reaction to chemically modify recombinantly expressed proteins under mild conditions. In particular, semisynthetic protein trans-splicing with one intein fragment short enough to be accessible by solid-phase peptide synthesis can be used to transfer a short peptide segment with the desired synthetic moiety to the protein of interest. In this chapter, we provide detailed protocols for two such split intein systems.

An atypical naturally split intein engineered for highly efficient protein labeling.

Protein trans-splicing catalyzed by split inteins is a powerful technique for assembling a polypeptide backbone from two separate parts. However, split inteins with robust efficiencies and short fragments suitable for peptide synthesis are rare and have mostly been artificially created. The novel split intein AceL-TerL was identified from metagenomic data and characterized.

Probing intein-catalyzed thioester formation by unnatural amino acid substitutions in the active site.

Inteins are single-turnover catalysts that splice themselves out of a precursor polypeptide chain. For most inteins, the first step of protein splicing is the formation of a thioester through an N-S acyl shift at the upstream splice junction. However, the mechanism by which this reaction is achieved and the impact of mutations in and close to the active site remain unclear on the atomic level.

Highly efficient and more general cis- and trans-splicing inteins through sequential directed evolution.

Inteins are internal protein sequences that post-translationally self-excise and splice together the flanking sequences, the so-called exteins. Natural and engineered inteins have been used in many practical applications. However, inteins are often inefficient or inactive when placed in a non-native host protein and may require the presence of several amino acid residues of the native exteins, which will then remain as a potential scar in the spliced protein.

Protein trans-splicing on an M13 bacteriophage: towards directed evolution of a semisynthetic split intein by phage display.

Split inteins link their fused peptide or protein sequences with a peptide bond in an autocatalytic reaction called protein trans-splicing. This reaction is becoming increasingly important for a variety of applications in protein semisynthesis, polypeptide circularisation, construction of biosensors, or segmental isotopic labelling of proteins. However, split inteins exhibit greatly varying solubility, efficiency and tolerance towards the nature of the fused sequences as well as reaction conditions.