Role of peptidyl-prolyl cis–trans isomerases in infectious diseases and host–pathogen interactions

Peptidyl-prolyl cis–trans isomerases (PPIases) catalyse the cis–trans isomerization of Ca atoms about the peptide bond preceding a proline residue, thereby regulating a conformational switch which controls a plethora of cellular processes. PPIases play a key role in the survival, reproduction, proliferation and virulence of microbial pathogens vis-à-vis their human host. In addition, human PPIases either aid or retard viral replication and modulate host immune response. The article discusses the structure–function relationships of PPIases in the context of microbial virulence (with an emphasis on viruses), and on targeting PPIases for COVID-19, responsible for untold human sufferings.