Bridging the gap: Unveiling novel functions of a bacterial haem-acquisition protein capturing diverse synthetic porphyrinoids

Certain bacterial pathogens secrete haemophores, i.e. extracellular haem-uptake proteins, which acquire haem as a vital source of iron in the iron-devoid environment of their hosts. The haem-binding site of haemophores is highly exposed to the protein surface, enabling them to pirate haem from other haem-containing proteins (haemoproteins). This review will discuss the hidden ability of a representative haemophore, namely the haem-acquisition system protein A (HasA) secreted by Pseudomonas aeruginosa, which can accommodate a diverse assortment of synthetic metal complexes possessing extreme insolu-bility and/or high steric bulk in its haem-binding site. The replacement of haem with similar synthetic analogues is an already well established and powerful means to change the function of select haemopro-teins; however, usable complexes are severely limited by the high selectivity of haemoproteins for haem. This review will introduce how combining the haem-replacement approach with HasA can open the door for the biological application of diverse synthetic metal complexes that were previously incompatible with biological systems. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

The haem-acquisition system protein A (HasA) has the ability to accommodate a variety of synthetic metal complexes and opens up biological applications for these previously incompatible complexes.