Structural features and oligomeric nature of human podocin domain

• Published in: Biochemistry and biophysics reports 2020-09, Vol.23, p.100774-100774, Article 100774
• Main Authors: Mulukala, Sandeep K.N., Irukuvajjula, Shivkumar S., Kumar, Krishan, Garai, Kanchan, Venkatesu, Pannuru, Vadrevu, Ramakrishna, Pasupulati, Anil K.
• Format: Article
• Language: English
• Subjects: Nephrotic syndrome; Podocin; Podocyte; Proteinuria; Slit-diaphragm
• ISSN: 2405-5808; 2405-5808
• DOI: 10.1016/j.bbrep.2020.100774

Podocytes are crucial cells of the glomerular filtration unit and plays a vital role at the interface of the blood-urine barrier. Podocyte slit-diaphragm is a modified tight junction that facilitates size and charge-dependent permselectivity. Several proteins including podocin, nephrin, CD2AP, and TRPC6 form a macromolecular assembly and constitute the slit-diaphragm. Podocin is an integral membrane protein attached to the inner membrane of the podocyte via a short transmembrane region (101–125). The cytosolic N- and C-terminus help podocin to attain a hook-like structure. Podocin shares 44% homology with stomatin family proteins and similar to the stomatin proteins, podocin was shown to associate into higher-order oligomers at the site of slit-diaphragm. However, the stoichiometry of the homo-oligomers and how it partakes in the macromolecular assemblies with other slit-diaphragm proteins remains elusive. Here we investigated the oligomeric propensity of a truncated podocin construct (residues:126–350). We show that the podocin domain majorly homo-oligomerizes into a 16-mer. Circular dichroism and fluorescence spectroscopy suggest that the 16-mer oligomer has considerable secondary structure and moderate tertiary packing. •Cloning, expression, and purification of truncated podocin (residues: 126–350).•The truncated podocin predominantly associates into 16mer oligomers.•The oligomers though possesses secondary structure lacks tight tertiary packing.•The oligomeric ensemble has different dissociation temperatures.