Molecular Insights into the Effects of F16L and F19L Substitutions on the Conformation and Aggregation Dynamics of Human Calcitonin

Fengjuan Huang; Jiahui Huang; Jiajia Yan; Yuying Liu; Jiangfang Lian; Qinxue Sun; Feng Ding; Yunxiang Sun

doi:10.1021/acs.jcim.4c00553

Molecular Insights into the Effects of F16L and F19L Substitutions on the Conformation and Aggregation Dynamics of Human Calcitonin

J Chem Inf Model. 2024 May 14. doi: 10.1021/acs.jcim.4c00553. Online ahead of print.

Authors

Fengjuan Huang^{1

2}, Jiahui Huang³, Jiajia Yan³, Yuying Liu³, Jiangfang Lian¹, Qinxue Sun¹, Feng Ding⁴, Yunxiang Sun^{3

4}

Affiliations

¹ Ningbo Institute of Innovation for Combined Medicine and Engineering, Lihuili Hospital Affiliated to Ningbo University, Ningbo University, Ningbo 315211, China.
² School of Medicine, Ningbo University, Ningbo 315211, China.
³ School of Physical Science and Technology, Ningbo University, Ningbo 315211, China.
⁴ Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, United States.

PMID: 38745385
DOI: 10.1021/acs.jcim.4c00553

Abstract

Human calcitonin (hCT) regulates calcium-phosphorus metabolism, but its amyloid aggregation disrupts physiological activity, increases thyroid carcinoma risk, and hampers its clinical use for bone-related diseases like osteoporosis and Paget's disease. Improving hCT with targeted modifications to mitigate amyloid formation while maintaining its function holds promise as a strategy. Understanding how each residue in hCT's amyloidogenic core affects its structure and aggregation dynamics is crucial for designing effective analogues. Mutants F16L-hCT and F19L-hCT, where Phe residues in the core are replaced with Leu as in nonamyloidogenic salmon calcitonin, showed different aggregation kinetics. However, the molecular effects of these substitutions in hCT are still unclear. Here, we systematically investigated the folding and self-assembly conformational dynamics of hCT, F16L-hCT, and F19L-hCT through multiple long-time scale independent atomistic discrete molecular dynamics (DMD) simulations. Our results indicated that the hCT monomer primarily assumed unstructured conformations with dynamic helices around residues 4-12 and 14-21. During self-assembly, the amyloidogenic core of hCT_14-21 converted from dynamic helices to β-sheets. However, substituting F16L did not induce significant conformational changes, as F16L-hCT exhibited characteristics similar to those of wild-type hCT in both monomeric and oligomeric states. In contrast, F19L-hCT exhibited substantially more helices and fewer β-sheets than did hCT, irrespective of their monomers or oligomers. The substitution of F19L significantly enhanced the stability of the helical conformation for hCT_14-21, thereby suppressing the helix-to-β-sheet conformational conversion. Overall, our findings elucidate the molecular mechanisms underlying hCT aggregation and the effects of F16L and F19L substitutions on the conformational dynamics of hCT, highlighting the critical role of F19 as an important target in the design of amyloid-resistant hCT analogs for future clinical applications.