Metal-binding selectivity and coordination dynamics for cyanobacterial microcystins with Zn, Cu, Fe, Mg, and Ca
- First Online:
- 86 Downloads
Microcystins are toxic cyclic peptides produced worldwide by cyanobacteria in surface caters. The general structure of microcystin is inherently amenable to metal complexation. However, structural characterization of metal–microcystin complexes is lacking. Here we performed molecular dynamics simulations to obtain structures of aqueous complexes of microcystin–leucine–arginine and microcystin–arginine–arginine with Ca2+, Mg2+, Fe2+, Zn2+, and Cu2+. Results show that complexes with Cu2+ and Zn2+ were the most stable. Shorter metal-O atom distances result in more favorable complexes. For instance, the relatively stronger Zn–microcystin complexes have metal-Ocarboxyl distances of 1.78 Å, whereas the weaker Ca–microcystin complexes have this distance greater than 2.0 Å. Favorable metal complexation is attributed to the conformation of the microcystin peptide cavity that facilitated a specific coordination geometry of carboxyl and keto O atoms around the metal cation. Our findings imply that the cellular and extracellular roles of microcystin with respect to metal chelation are controlled both by the metal species and by the population of microcystin variants.
KeywordsMicrocystin Metal complexes Molecular dynamics Modeling
- Accelrys Software I (2013) Materials studio modeling environment, release 7.0. Accelrys Software Inc., San DiegoGoogle Scholar
- Qi Y, Rosso L, Sedan D, Giannuzzi L, Andrinolo D, Volmer DA (2015) Seven new microcystin variants discovered from a native Microcystis aeruginosa strain–unambiguous assignment of product ions by tandem mass spectrometry. Rapid Commun Mass Spectrom 29:220–224. doi:10.1002/rcm.7098 CrossRefGoogle Scholar
- Stumm W, Morgan JJ (1996) Aquatic chemistry: chemical equilibria and rates in natural waters, 3rd edn. Wiley, New YorkGoogle Scholar