4G cloning: rapid gene assembly for expression of multisubunit protein complexes in diverse hosts.

Multisubunit protein complexes are central to many cellular processes, and studying their activities and structures in vitro requires reconstitution via recombinant expression and purification. Obtaining targets at sufficient purity and scale typically involves screening several protein variants and expression hosts. Existing cloning strategies enable co-expression but are often time-consuming, labor-intensive, and host-specific, or involve error-prone steps. We present a novel vector set and assembly strategy to overcome these limitations, enabling expression construct generation for multisubunit complexes in a single step. This modular system can be extended to additional hosts or include new tags. We demonstrate its utility by constructing expression vectors for structural maintenance of chromosomes complexes in various hosts, streamlining workflows, and improving productivity.