A structured interdomain linker directs self-polymerization of human uromodulin.

Abstract

Uromodulin (UMOD)/Tamm-Horsfall protein, the most abundant human urinary protein, plays a key role in chronic kidney diseases and is a promising therapeutic target for hypertension. Via its bipartite zona pellucida module (ZP-N/ZP-C), UMOD forms extracellular filaments that regulate kidney electrolyte balance and innate immunity, as well as protect against renal stones. Moreover, salt-dependent aggregation of UMOD filaments in the urine generates a soluble molecular net that captures uropathogenic bacteria and facilitates their clearance. Despite the functional importance of its homopolymers, no structural information is available on UMOD and how it self-assembles into filaments. Here, we report the crystal structures of polymerization regions of human UMOD and mouse ZP2, an essential sperm receptor protein that is structurally related to UMOD but forms heteropolymers. The structure of UMOD reveals that an extensive hydrophobic interface mediates ZP-N domain homodimerization. This arrangement is required for filament formation and is directed by an ordered ZP-N/ZP-C linker that is not observed in ZP2 but is conserved in the sequence of deafness/Crohn's disease-associated homopolymeric glycoproteins α-tectorin (TECTA) and glycoprotein 2 (GP2). Our data provide an example of how interdomain linker plasticity can modulate the function of structurally similar multidomain proteins. Moreover, the architecture of UMOD rationalizes numerous pathogenic mutations in both UMOD and TECTA genes.

• Authors: Marcel Bokhove, Kaoru Nishimura, Martina Brunati, Ling Han, Daniele de Sanctis, Luca Rampoldi, Luca Jovine
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 113 Issue 6 Pg. 1552-7 (Feb 09 2016) ISSN: 1091-6490 [Electronic] United States
• PMID: 26811476 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Disulfides
• Extracellular Matrix Proteins
• GPI-Linked Proteins
• Maltose-Binding Proteins
• Recombinant Fusion Proteins
• TECTA protein, human
• Uromodulin

Topics

• Amino Acid Sequence
• Animals
• Blotting, Western
• Crystallography, X-Ray
• Disulfides (metabolism)
• Dogs
• Extracellular Matrix Proteins (genetics)
• Fluorescent Antibody Technique
• GPI-Linked Proteins (genetics)
• HEK293 Cells
• Humans
• Madin Darby Canine Kidney Cells
• Maltose-Binding Proteins (metabolism)
• Mice
• Models, Molecular
• Molecular Sequence Data
• Mutation, Missense (genetics)
• Polymerization
• Protein Multimerization
• Protein Structure, Tertiary
• Recombinant Fusion Proteins (metabolism)
• Sequence Alignment
• Structural Homology, Protein
• Uromodulin (chemistry, ultrastructure)