Multiheme proteins: effect of heme-heme interactions

The family of multiheme proteins constitutes one of the fascinating molecular machineries designed by Nature to execute a large variety of functions. A high level of conservation among the structural arrangement of heme units is evident among various multiheme cytochromes. The relative arrangement of the heme centers and the intermacrocyclic interactions therein have been found to exhibit a major role in functional properties of such a widely distributed family. The existence of more than one heme center provides an effective and efficient tool to modulate various structures and properties that are needed for its function. This Frontier overviews a brief account of our on-going efforts to examine some of the design principles in which the inter-heme distance and their relative orientations are appropriately chosen to elucidate, at the molecular level, the effects of heme-heme interactions and electronic communication in the synthetic dihemes. This Frontier illustrates a brief personal account on the effect of heme-heme interactions in dihemes which thereby discloses some of the evolutionary design principles involved in multiheme proteins for their diverse structures and functions.