Figure 8. Schematic overview for how TraA-mediated cell-cell interactions can contribute toward myxobacterial social behaviors.

Cell genotypes and TraA receptors are color coded to indicate genetic relatedness. Related TraA receptors bind through proposed homophilic interactions. Populations of low genetic diversity would likely result in only sibling interactions, whereas diverse populations could result in non-kin interactions and could contribute toward group selection dynamics [45]. Subsequent OM fusion and component exchange results in the indicated social outcomes. The ability of non-kin cells to interact could result in positive fitness outcomes. For example, if two distinct M. xanthus populations are of insufficient size to build a fruiting body, their combined populations, as mediated by TraA interactions, may be able to surmount this barrier.