Structural analysis of human NHLRC2, mutations of which are associated with FINCA disease

Ekaterina Biterova; Alexander Ignatyev; Johanna Uusimaa; Reetta Hinttala; Lloyd W Ruddock

doi:10.1371/journal.pone.0202391

Structural analysis of human NHLRC2, mutations of which are associated with FINCA disease

PLoS One. 2018 Aug 23;13(8):e0202391. doi: 10.1371/journal.pone.0202391. eCollection 2018.

Authors

Ekaterina Biterova^{1

2

3}, Alexander Ignatyev^{1

2}, Johanna Uusimaa^{2

3

4}, Reetta Hinttala^{2

3}, Lloyd W Ruddock^{1

2}

Affiliations

¹ Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland.
² Biocenter Oulu, University of Oulu, Oulu, Finland.
³ PEDEGO Research Unit and Medical Research Center Oulu, University of Oulu and Oulu University Hospital, Oulu, Finland.
⁴ Department of Children and Adolescents, Oulu University Hospital, Oulu, Finland.

Abstract

NHLRC2 (NHL repeat-containing protein 2) is an essential protein. Mutations of NHLRC2, including Asp148Tyr, have been recently associated with a novel FINCA disease (fibrosis, neurodegeneration, cerebral angiomatosis), which is fatal in early childhood. To gain insight into the mechanisms of action of this essential protein, we determined the crystal structure of the Trx-like and NHL repeat β-propeller domains of human NHLRC2 to a resolution of 2.7 Å. The structure reveals two domains adjacent to each other that form a cleft containing a conserved CCINC motif. A SAXS structure of full-length NHLRC2 reveals that the non-conserved C-terminal domain does not pack against the N-terminal domains. Analysis of the surface properties of the protein identifies an extended negative electrostatic potential in the surface of the cleft formed by the two domains, which likely forms a binding site for a ligand or interaction partner(s). Bioinformatics analysis discovers homologs across a range of eukaryotic and prokaryotic species and conserved residues map mostly to the adjacent surfaces of the Trx-like and β-propeller domains that form the cleft, suggesting both that this forms the potential functional site of NHLRC2 and that the function is conserved across species. Asp148 is located in the Trx-like domain and is not conserved across species. The Asp148Tyr mutation destabilizes the structure of the protein by 2°C. The NHLRC2 structure, the first of any of its homologs, provides an important step towards more focused structure-function studies of this essential protein.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Amino Acid Substitution
Angiomatosis*
Carrier Proteins / chemistry*
Carrier Proteins / genetics
Fibrosis
Heredodegenerative Disorders, Nervous System*
Humans
Mutation, Missense*
Protein Domains
Scattering, Small Angle
X-Ray Diffraction

Substances

Carrier Proteins

Grants and funding

This work was supported by the Academy of Finland (http://www.aka.fi/en; grant numbers 266457 and 272573 (LWR), 266498 and 303996 (RH)) and Biocenter Oulu. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.