Human myelin protein P2: from crystallography to time‐lapse membrane imaging and neuropathy‐associated variants. (14th July 2021)

• Record Type: Journal Article
• Authors: Uusitalo, Maiju; Klenow, Martin Berg; Laulumaa, Saara; Blakeley, Matthew P.; Simonsen, Adam Cohen; Ruskamo, Salla; Kursula, Petri
• Is Part Of: FEBS journal. Volume 288:Number 23(2021)
• Page Start: 6716
• Page End: 6735
• Publication Date: 2021-07-14
• Subjects: Charcot–Marie–Tooth disease -- fatty acid‐binding protein -- lipid binding -- mutation -- myelin protein P2 -- protein structure; Biochemistry -- Periodicals; Molecular biology -- Periodicals; Pathology, Molecular -- Periodicals; 572
• DOI: 10.1111/febs.16079
• Languages: English
• ISSNs: 1742-464X

Abstract

Abstract : Peripheral myelin protein 2 (P2) is a fatty acid‐binding protein expressed in vertebrate peripheral nervous system myelin, as well as in human astrocytes. Suggested functions of P2 include membrane stacking and lipid transport. Mutations in the PMP2 gene, encoding P2, are associated with Charcot–Marie–Tooth disease (CMT). Recent studies have revealed three novel PMP2 mutations in CMT patients. To shed light on the structure and function of these P2 variants, we used X‐ray and neutron crystallography, small‐angle X‐ray scattering, circular dichroism spectroscopy, computer simulations and lipid binding assays. The crystal and solution structures of the I50del, M114T and V115A variants of P2 showed minor differences to the wild‐type protein, whereas their thermal stability was reduced. Vesicle aggregation assays revealed no change in membrane stacking characteristics, while the variants showed altered fatty acid binding. Time‐lapse imaging of lipid bilayers indicated formation of double‐membrane structures induced by P2, which could be related to its function in stacking of two myelin membrane surfaces in vivo . In order to better understand the links between structure, dynamics and function, the crystal structure of perdeuterated P2 was refined from room temperature data using neutrons and X‐rays, and the results were compared to simulations and cryocooled crystal structures. Our data indicate similar properties for all known human P2 CMT variants; while crystal structures are nearly identical, thermal stability and function of CMT variants are impaired. Our data provide new insights into the structure–function relationships and dynamics of P2 in health and disease. Abstract : P2 is a protein of peripheral nerve myelin. We studied human P2 and three recently identified disease mutations. The data indicate effects on P2 thermal stability and dynamics by the mutations. Furthermore, room temperature crystallography using X‐rays and neutrons was used to get additional insights into P2 dynamics. Time‐lapse imaging of membrane layers showed effects of P2 on lipid membrane morphology. Overall, an improved understanding emerges about P2 structure and function.