Structural studies of various hemocyanins in different conformations/functional states

• Grant number: 25/09969-1
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: August 01, 2025
• End date: May 31, 2027
• Field of knowledge: Biological Sciences - Biochemistry - Chemistry of Macromolecules
• Principal Investigator: Marin Gerard van Heel
• Grantee: Angela Rocio Nino Santisteban
• Host Institution: Centro Nacional de Pesquisa em Energia e Materiais (CNPEM). Ministério da Ciência, Tecnologia e Inovação (Brasil). Campinas , SP, Brazil
• Associated research grant: 20/06062-1 - Biological complexes in action, in vitro and in silico (Exploiting Big-Data in Cryo-EM), AP.TEM

Abstract

Most spiders breathe with both diffusion lungs and tracheae and have hemocyanin as their respiratory pigment [Prestwich 1983]. Almost all different spider families have specific morphological and physiological characteristics. Higher developed spiders, with a welldeveloped tracheal system, tend to have a reduced concentration/function of their respiratory pigment and an increased maximum metabolic rate [Schmitz 2016]. Hemocyanins are freely dissolved in the hemolymph of arthropods; and they are large allosteric proteins comprised of multiple hexamers whereby each hexamer consists of (different) monomers of about 75 kDa. Arthropod hemocyanins molecular weights range from 450 kDa in a single hexamer (the spiny lobster (Panulirus interruptus) to up to more than 3.6 mDa organized as 8 hexamers (a 48-mer) in the horseshoe crab (Limulus polyphemus). Arthropod hemocyanins, being large and easy to prepare, were among the first macromolecules studied by multivariate statistical image analysis techniques [van Heel & Frank 1981] and automatic classification [van Heel 1984]. Indeed, even the introduction the main current resolution metric the Fourier Ring Correlation (FRC) was initiated in the context of a hemocyanin study [van Heel 1982]. Very few details of the allosteric oxygen-binding properties of hemocyanins - and their structural origin - are currently known. Knowledge of the quaternary structures of this intricate hierarchical family of oligomers is essential for understanding the allosteric interactions associated with their strong oxygen-binding cooperativity. Moreover, there are a large number of structures to be studied of many species of great ecological importance for Brazil. This hemocyanin project will especially focus on Methodology development especially for methods dealing with local variability [Bhakta& Van Heel 2024]. Their large size make them excellent samples to study local and global resolution/information methodologies. (AU)