Biology subjects

Cordes, M. H. J.

Publications and source records attributed to Cordes, M. H. J..

2 recordsLinked to original sources

bioRxiv2021

Specificity of Loxosceles α clade phospholipase D enzymes for choline-containing lipids: role of a conserved aromatic cage

Spider venom GDPD-like phospholipases D (SicTox) have been identified to be one of the major toxins in recluse spider venom. They are divided into two major clades: the clade and the {beta} clade. Most clade toxins present high activity against lipids with choline head groups such as sphingomyelin, while activities in {beta} clade toxins vary and include preference for substrates containing ethanolamine headgroups (Sicarius terrosus, St_{beta}IB1). A structural comparison of available PLDs structures reveals a conserved aromatic cage in the clade. To test the potential influence of the aromatic cage on membrane-lipid specificity we performed molecular-dynamics (MD) simulations of the binding of several PLDs onto lipid bilayers containing choline headgroups; two SicTox from the clade, Loxosceles intermedia IA1 (Li_IA) and Loxosceles laeta III1 (Ll_III1), and one from the {beta} clade, St_{beta}IB1. The simulation results reveal that the aromatic cage captures a choline-headgroup and suggest that the cage plays a major role in lipid specificity. We also simulated an engineered St_{beta}IB1, where we introduced the aromatic cage, and this led to binding with choline-containing lipids. Moreover, a multiple sequence alignment revealed the conservation of the aromatic cage among the clade PLDs. Here, we confirmed the membrane binding site of and {beta} clade PLDs on choline and ethanolamine-containing bilayers, respectively. Furthermore, our results suggest a major role in choline lipid recognition of the aromatic cage of the clade PLDs. The MD simulation results are supported by in vitro liposome binding assay experiments.

bioinformatics↗

bioRxiv2017

Progressively more subtle aggregation avoidance strategies mark a long-term direction to protein evolution

To detect a direction to evolution, without the pitfalls of reconstructing ancestral states, we need to compare \"more evolved\" to \"less evolved\" entities. But because all extant species have the same common ancestor, none are chronologically more evolved than any other. However, different gene families were born at different times, allowing us to compare young protein-coding genes to those that are older and hence have been evolving for longer. To be retained during evolution, a protein must not only have a function, but must also avoid toxic dysfunction such as protein aggregation. There is conflict between the two requirements; hydrophobic amino acids form the cores of protein folds, but also promote aggregation. Young genes avoid strongly hydrophobic amino acids, which is presumably the simplest solution to the aggregation problem. Here we show that young genes few hydrophobic residues are clustered near one another along the primary sequence, presumably to assist folding. The higher aggregation risk created by the higher hydrophobicity of older genes is counteracted by more subtle effects in the ordering of the amino acids, including a reduction in the clustering of hydrophobic residues until they eventually become more interspersed than if distributed randomly. This interspersion has previously been reported to be a general property of proteins, but here we find that it is restricted to old genes. Quantitatively, the index of dispersion delineates a gradual trend, i.e. a decrease in the clustering of hydrophobic amino acids over billions of years.

evolutionary biology↗