Plant Cyclophilins: Multifaceted Proteins With Versatile Roles

Abstract

Cyclophilins constitute a family of ubiquitous proteins that bind cyclosporin A (CsA), an immunosuppressant drug. Several of these proteins possess peptidyl-prolyl cis-trans isomerase (PPIase) activity that catalyzes the cis-trans isomerization of the peptide bond preceding a proline residue, essential for correct folding of the proteins. Compared to prokaryotes and other eukaryotes studied until now, the cyclophilin gene families in plants exhibit considerable expansion. With few exceptions, the role of the majority of these proteins in plants is still a matter of conjecture. However, recent studies suggest that cyclophilins are highly versatile proteins with multiple functionalities, and regulate a plethora of growth and development processes in plants, ranging from hormone signaling to the stress response. The present review discusses the implications of cyclophilins in different facets of cellular processes, particularly in the context of plants, and provides a glimpse into the molecular mechanisms by which these proteins fine-tune the diverse physiological pathways.

Genome-wide characterization of peptidyl-prolyl cis–trans isomerases in Penicillium and their regulation by salt stress in a halotolerant P. oxalicum

“…Estimation of the PPIase proteins by immunoblotting is, nonetheless, required to understand the molecular basis of this observation. Since protection by cyclophilins and FKBPs against stress-induced damage to the cell is attributed to their PPIase activity and/or chaperone functions 80 , further biochemical characterization of these proteins in Penicillium is imperative to elucidate their precise mechanism of action. Although expression of other PPIases was not observed at the stages studied, their role in specific developmental processes and adaptation to other stresses cannot be ruled out as previous studies have demonstrated the role of these genes in the regulation of several developmental process 80 .…”

Genetic and Proteomic Basis of Sclerotinia Stem Rot Resistance in Indian Mustard [Brassica juncea (L.) Czern & Coss.]

“…PPIases are the class of stress-responsive proteins of the immunophilin family. It catalyzes various biological functions such as transcription regulation, protein folding and degradation, signal transduction, and reactive oxygen species (ROS) regulation, cell wall strengthening to cope with stress conditions [66][67][68][69][70]. A plethora of recent reports indicate that PPIases are critical resistance/tolerance factors against various biotic and abiotic stresses in crops [69,[71][72][73][74][75].…”

Proteomic Studies of Roots in Hypoxia-Sensitive and -Tolerant Tomato Accessions Reveal Candidate Proteins Associated with Stress Priming

“…PPIases, also called immunophilins, are a family of ubiquitous proteins with multiple functionalities in plants [50]. Two subfamilies are known: cyclophilins (CYPs) and FK506 binding proteins (FKBPs).…”