Theoretical-experimental studies of calmodulin-peptide interactions at different calcium equivalents

Abstract

We study the CaM-peptide interactions for four CaM-related peptides with different calcium equivalents, using the hCaM-M124C-mBBr biosensor and Molecular Dynamics (MD). Due to the high sensitivity of the biosensor, we were able to calculate five K_ds based on the number of calcium equivalents for each peptide, showing a directly proportional relationship between the degree of calcium saturation and the increased affinity for the Calspermin, nNOS, and skMLSK peptides; while the CaV1.1 peptide has a degree of affinity independent of the number of calcium equivalent. On the other hand, the MD studies were designed based on the experimental results; I) visualizing the effect of the gradual elimination of calcium in Holo-CaM and II) analyzing the CaM-Peptide complexes with and without calcium. We observe that the gradual addition of calcium increases the flexibility of Holo-CaM. Concerning CaM-Peptide complexes, it presents differences in both the ΔG_T and the RMSD. These results demonstrate the importance of the use of biosensors and the power of MD to make inferences in systems such as CaM-peptide complexes.

Communicated by Ramaswamy H. Sarma

Keywords:

• CaM-peptide
• molecular modeling tools
• calcium
• molecular dynamic (MD)
• biosensors
• calmodulin
• calspermin
• CaV1.1
• nNOS
• and skMLCK

Acknowledgements

The authors are very grateful to Mrs. Maria Josefina Bolado Garza from the División de Investigación, Facultad de Medicina, UNAM for the review and edition of the manuscript. We are indebted to Dirección General de Cómputo y de Tecnologías de Información y Comunicación, UNAM, for providing the resources to carry out computational calculations through MIZTLI System.

Disclosure statement

No potential conflict of interest was reported by the author

Additional information

Funding

This work was supported by grants from DGAPA-UNAM (PAPIIT-IN203719), DGTIC-UNAM (LANCAD-UNAM-DGTIC-313) and internal budget awarded from the Faculty of Medicine, UNAM.