A distinct molecular signature on anhydrobiotic cyanobacterial metallothioneins

Danyel Fernandes Contiliani,Yasmin De Araújo Ribeiro,Vitor Nolasco De Moraes,Tiago Campos Pereira

doi:10.33448/rsd-v10i2.12714

Danyel Fernandes Contiliani, Yasmin De Araújo Ribeiro + Show 2 more

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https://doi.org/10.33448/rsd-v10i2.12714

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Abstract

Anhydrobiosis refers to a state of suspended animation in which some organisms enter when exposed to extreme desiccation, ensuring them an outstanding tolerance to several physical stresses due to molecular and cellular adaptations. Metallothioneins (MTs) are short cysteine-rich metal-chelating proteins that work as a cellular protection element in metal ion-rich conditions. Here we aimed to investigate possible molecular signatures in primary and tertiary structures in anhydrobiotic cyanobacterial MTs. Anhydrobiotic and non-anhydrobiotic cyanobacterial MT amino acid sequences were retrieved from NCBI database and aligned in Clustal Omega server. Additionally, the amino acid compositions of these sequences were determined by GeneRunner. Further, we carried out homology-modeling via SWISS-MODEL, structural superposition in UCSF Chimera 1.4 Matchmaker tool and ligand-binding site prediction via COFACTOR. In silico analyses revealed specific divergences in amino acid positions between MT groups, evidencing positive and negative selections, however without affecting final protein structures. Some of these changes on polypeptide sequence potentially enhance protein stabilization during desiccation, whereas others possibly act as additional metal-ion coordinating residues. Analyses on the molecular adaptations on anhydrobiotic cyanobacterial MTs help shed light on their molecular functions and biological roles, as well as may have applications on the development of desiccation- and metal-tolerant organisms.

Highlights

IntroductionAnhydrobiosis (life without water) is a reversible ametabolic state of suspended animation, in which some (anhydrobiotic) organisms enter when exposed to extreme desiccation and can withstand osmotic imbalances for decades (Hibshman et al, 2020)
Anhydrobiosis is a reversible ametabolic state of suspended animation, in which some organisms enter when exposed to extreme desiccation and can withstand osmotic imbalances for decades (Hibshman et al, 2020)
Due to the high heterogeneity of MT primary sequences, we focused on cyanobacterial MTs because of their conserved secondary and tertiary structures (Blindauer, 2011)

Summary

Introduction

Anhydrobiosis (life without water) is a reversible ametabolic state of suspended animation, in which some (anhydrobiotic) organisms enter when exposed to extreme desiccation and can withstand osmotic imbalances for decades (Hibshman et al, 2020). Desiccated anhydrobiotic organisms display tolerance to several physical stresses, such as extreme temperatures, high hydrostatic pressures and ionizing radiation (Hibshman et al, 2020). Metallothioneins (MTs) are short-chain (near 50 amino acids) metal-binding proteins with a high amount of cysteine residues, which are responsible for strong interactions with metal ions (Capdevila & Atrian, 2011), such as Zinc (Zn2+) and Copper (Cu). MT primary structures display α and β domains (C-terminal and N-terminal, respectively), which display high amino acid heterogeneity, whilst only cysteine metal-coordinating residues are conserved (Capdevila & Atrian, 2011)

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