Engineering protein prenylation: an emerging tool for selective protein modification

Prenyltransferases catalyze the attachment of isoprenoids to cysteine residues located near the C-termini of proteins including those containing a 'CaaX' tetrapeptide motif. This enzyme family includes farnesyl transferase (FTase), geranylgeranyltransferase type I (GGTase I), and GGTase type II (GGTase II). The CaaX motif broadly consists of cysteine (C), two aliphatic residues (a), and a variable residue (X), which determines substrate specificity for farnesylation and type I geranylgeranylation. This review primarily focuses on FTase-mediated protein modification strategies for assembling therapeutically valuable proteins. First, the process of protein prenylation and the structural features of the FTase active site are discussed. This is followed by an exploration of FTase-catalyzed bioconjugation of monomeric proteins and peptides, emphasizing its efficiency, modularity, and potential for industrial biological applications. The broader applicability of this approach is then highlighted in the design and assembly of multimeric protein structures, facilitating the development of complex biomolecular architectures with enhanced functionality, stability, and therapeutic potential. Finally, FTase mutagenesis strategies are examined that expand substrate scope, accommodating diverse functional groups for a wide range of biotechnological and therapeutic applications.