Recombinant Human pucL protein

PucL is a light-harvesting protein component primarily studied in photosynthetic bacteria, notably within the *Rhodobacter* genus, such as *Rhodobacter sphaeroides* and *Rhodobacter capsulatus*. It plays a critical role in the assembly and stability of the peripheral light-harvesting complex II (LHII), which is responsible for capturing solar energy and transferring it to the reaction center for conversion into chemical energy. The *pucL* gene is part of the *puc* operon, which encodes multiple polypeptides (e.g., PucA, PucB) that form the LHII complex’s structural framework. Unlike the core light-harvesting complex I (LHI), LHII absorbs longer wavelengths of light, expanding the organism’s spectral range for energy absorption in low-light conditions. PucL is essential for proper LHII oligomerization and integration into the bacterial photosynthetic membrane, though its exact mechanistic role—whether in pigment binding, membrane anchoring, or complex stabilization—remains under investigation.

Recombinant PucL production typically involves heterologous expression in *Escherichia coli*, where the protein is cloned into plasmid vectors under inducible promoters (e.g., T7 or araBAD). Affinity tags (e.g., His-tag) facilitate purification via chromatography. Challenges include ensuring proper folding and post-translational modifications, as PucL is a membrane-associated protein requiring lipid interactions for functionality. Researchers often employ detergent solubilization or cell-free systems to mimic native membrane environments. Studies on recombinant PucL aim to elucidate its structural dynamics using techniques like cryo-EM or X-ray crystallography, as well as its interactions with bacteriochlorophylls and carotenoids. Beyond basic research, engineered PucL variants hold potential in bioenergy (e.g., enhancing artificial photosynthesis) and biotechnology (e.g., biosensors). However, functional reconstitution of LHII *in vitro* remains technically demanding, necessitating further optimization of expression and purification protocols. Understanding PucL’s role advances synthetic biology efforts to design hybrid photosynthetic systems and improve solar energy harvesting efficiency.