Aromatic π-networks in Sm/LSm protein interfaces

Abstract

In this work, we have analyzed the influence of π-π interactions on stability and properties of Sm/LSm assemblies. The residues were found to be involved in π-π interactions much more frequently than Tyr or His. Similarly, the Phe-Phe π-π interacting pair had the highest frequency of occurrence. Furthermore, a significant number of π-networks were observed at the interface of Sm/LSm proteins. Generally speaking, the distance between the interacting pairs was in the range of 5-6 Å. 3π and 7π-networks were found to frequently have plane-plane angles less than 60º. Solvent accessibility pattern of Sm/LSm proteins revealed that all of the interacting residues were from buried areas. Moreover, most of the π-π interacting residues of Sm/LSm proteins were evolutionary conserved and were in the strand regions. A high percentage of these residues could be considered as stabilization centers that (significantly) contribute to the net stability of Sm/LSm proteins.

U ovom radu smo analizirali uticaj π-π interakcija na stabilnost i osobine Sm/LSm proteinskih agregata. Ostatak fenilalanina znatno češće uzima učešće u π-π interakcijama u odnosu na His i Tyr. Slično, Phe-Phe π-π interagujući parovi su najučestaliji. Prepoznat je značajan broj π-mreža u interfejsima Sm/LSm proteinima. U većini slučajeva, rastojanje između interagujućih parova aminokiselina bilo je u opsegu 5-6 Å. Za 3π i 7π-mreže, prsten-prsten uglovi manji od 60º su bili učestaliji. Razmatrajući delove Sm/LSm proteina dostupne rastvaraču, može se zaključiti da se svi interagujući parovi nalaze u unutrašnjim regionima. Pored toga, većina π-π interagujućih aminokiselinskih ostataka je evoluciono konzervativan i nalazi se u regionima sa nabranom strukturom. Veliki broj ovih ostataka se može smatrati stabilizacionim centrima, koji (značajno) doprinose ukupnoj stabilnost Sm/LSm proteina.