The conservation of IAP-like proteins in fungi, and their potential role in fungal programmed cell death

Programmed cell death (PCD) is a tightly regulated process which is required for survival and proper develop-ment of all cellular life. Despite this ubiquity, the precise molecular underpinnings of PCD have been primarily characterized in animals. Attempts to expand our understanding of this process in fungi have proven difficult as core regulators of animal PCD are apparently absent in fungal genomes, with the notable exception of a class of proteins referred to as inhibitors of apoptosis proteins (IAPs). These proteins are characterized by the conser-vation of a distinct Baculovirus IAP Repeat (BIR) domain and animal IAPs are known to regulate a number of processes, including cellular death, development, organogenesis, immune system maturation, host-pathogen interactions and more. IAP homologs are broadly conserved throughout the fungal kingdom, but our under-standing of both their mechanism and role in fungal development/virulence is still unclear. In this review, we provide a broad and comparative overview of IAP function across taxa, with a particular focus on fungal pro-cesses regulated by IAPs. Furthermore, their putative modes of action in the absence of canonical interactors will be discussed.

Automated summary

Programmed cell death (PCD) is a crucially regulated process for the survival and development of all cellular life, extensively studied in animals but less understood in fungi. Inhibitors of apoptosis proteins (IAPs), broadly conserved in the fungal kingdom, play a role in fungal development and virulence, although their mechanisms and functions remain unclear.