In-Silico Study of Protein-Protein Interaction, Secondary Structural Analysis and Annotation of Functional Domains of Indoleamine 2,3-Dioxygenase1

Abstract

Indoleamine-2,3-dioxygenase-1 (IDO1) is the first catabolizing enzyme of tryptophan. IDO1 is extensively expressed in both immune and non-immune tissues and its activation is related to inflammation as well as severity of depressive symptoms, leading neurodegeneration and anxiety like behaviors. Moreover, IDO1 acts as novel immune checkpoint protein with regulatory pathways of immune response and may interact with several proteins. In this paper, physicochemical characterization, functional characterization, subcellular localization, secondary structural analysis and domains/motif/family of IDO1 interacting proteins were done using in silico tools such as STRING, ProtParam-Expasy, SOSUI, SOPMA and MOTIF Search. Eighteen interacting proteins were obtained by STRING. Briefly, all interacting proteins were hydrophilic in nature except AANAT. MAOA and MAOB were almost similar to each other and predicted as more stable in high range of temperature. Further, all interacting proteins showed diverse secondary structure. Higher percentage of α-helix structure was present in remaining proteins except KYNU, MAOA, IL4I1, MAOB and 4930438A08RIK. These proteins showed higher percentage of random coil. Moreover, almost equal percentage of α-helix and random coil were present in TPH1. Secondary structure β-turn was low in percentage in comparison to all other secondary structures. Taken together IDO1 interacting protein or enzyme which are involved in tryptophan catabolic process to kynurenine, serotonin synthesis, tryptophan metabolism, response to corticosterone and glucocorticoids, several other biological process. Such studies are useful to understand IDO1 dependent regulation in the context of tryptophan/kynurenine pathway and helpful in therapeutics of neurological disorders.