Structural features and oligomeric nature of human podocin domain.
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.
['Mulukala|Sandeep K N|SKN|', 'Irukuvajjula|Shivkumar S|SS|', 'Kumar|Krishan|K|', 'Garai|Kanchan|K|', 'Venkatesu|Pannuru|P|', 'Vadrevu|Ramakrishna|R|', 'Pasupulati|Anil K|AK|']
Podocin Podocyte Slit-diaphragm CD, Circular dichroism CD2AP, CD-2 associated protein GFB, Glomerular filtration barrier IDRs, Intrinsically disordered regions MALS, multi-angle light scattering NEPH, Nephrin-like protein NPHS1 & 2, Nephrotic syndrome-type I and type II NS, Nephrotic syndrome Nephrotic syndrome Proteinuria SD, slit-diaphragm SEC, Size-exclusion chromatography SRNS, steroid-resistant NS TRPC6, Transient receptor potential cation channel subfamily C member 6 ZO-1, Zonula occludens-1