why are spiders so fast? A small biochemical history

GARCIA CF; LAINO A; CARRASCO-MIRANDA, JESÚS S.; STAJANOFF ; SOTELO-MUNDO, ROGERIO R.

Congreso; 21 st International Congress of Arachnology.; 2019

Spiders are characterized by being hunter animals. This implies that they must develop great speed to be able to catch their prey, and even jump on them; this characteristic is very well developed in spiders that do not generate web, as is the case of Polybetes pythagoricus. At present no records are found of how spiders get energy to make such movements so fast because the aerobic routes seem to be insufficient, but the most consistent hypothesis is that they obtain it through the enzyme arginine kinase. In this work, we studied for the first time in spiders (using Polybetes pythagoricus) the arginine kinase (PpAK). The cDNA of PpAK was cloned, which is comprised of 1068 nucleotides that encode a 384-amino-acid protein with a calculated mass of 43 kDa. The sequence displays extensive similarity to other invertebrate arginine kinases (spider, tick, horseshoe crab and crustaceans). The apparent Michaelis-Menten kinetic constant (Km) and maximum velocity (Vmax) were 1.703 mM and 27.77 μmol.min-1.mg protein-1, respectively. The crystal structure shown with both ligand free and arginine binary complex were found in the open conformation with loop comprised from residues (310-320) fully disordered and not covering the active site as in the ternary complex reported for other guanidine kinases. Finally, these results contribute to the knowledge of mechanistic details of spider?s arginine kinases function y reports important data on DNA (GenBank MF001441) and protein (data bank. (http://www.rcsb.org/pdb/explore/explore.do?structureId=5U92)).