ARL15, a GTPase implicated in rheumatoid arthritis, potentially repositions its truncated N-terminus as a function of guanine nucleotide binding.

Abstract

The ADP ribosylation factor like protein 15 (ARL15) gene encodes for an uncharacterized GTPase associated with rheumatoid arthritis (RA) and other metabolic disorders. Investigation of the structural and functional attributes of ARL15 is important to position the protein as a potential drug target. Using spectroscopy, we demonstrated that ARL15 exhibits properties inherent of GTPases. The Km and Vmax of the enzyme were calculated to be 100 μM and 1.47 μmole/min/μL, respectively. The equilibrium dissociation constant (Kd) of GTP binding with ARL15 was estimated to be about eight-fold higher than that of GDP. Small Angle X-ray Scattering (SAXS) data indicated that in solution, the apo state of monomeric ARL15 adopts a shape characterized by a globe of maximum linear dimension (Dmax) of 6.1 nm, and upon binding to GTP or GDP, the vector distribution profile changes to peak-n-tail shoulder with Dmax extended to 7.6 and 7.7 nm, respectively. Structure restoration using a sequence-based template and experimental SAXS data provided the first visual insight revealing that the folded N-terminal in the unbound state of the protein may toggle open upon binding to guanine nucleotides. The conformational dynamics observed in the N-terminal region offer a scope to develop drugs that target this unique GTPase, potentially providing treatments for a range of metabolic disorders.

• Authors: Manisha Saini, Neelam Upadhyay, Kanika Dhiman, Satish Kumar Manjhi, Aman Achutan Kattuparambil, Antara Ghoshal, Richa Arya, Sanjay Kumar Dey, Aditya Sharma, Raviprasad Aduri, B K Thelma, Fnu Ashish, Suman Kundu
• Journal: International journal of biological macromolecules (Int J Biol Macromol) Vol. 254 Issue Pt 2 Pg. 127898 (Jan 2024) ISSN: 1879-0003 [Electronic] Netherlands
• PMID: 37939768 (Publication Type: Journal Article)
• Copyright: Copyright © 2023 Elsevier B.V. All rights reserved.

Chemical References

• Guanine Nucleotides
• Nucleotides
• Guanine
• ADP-Ribosylation Factors
• Proteins
• Guanosine Triphosphate
• Guanosine Diphosphate
• ARL15 protein, human

Topics

• Humans
• Guanine Nucleotides
• Nucleotides (metabolism)
• Guanine
• Scattering, Small Angle
• X-Ray Diffraction
• ADP-Ribosylation Factors (genetics, metabolism)
• Proteins (metabolism)
• Arthritis, Rheumatoid
• Guanosine Triphosphate (metabolism)
• Metabolic Diseases
• Guanosine Diphosphate