Effects of amino acids on assembling of an archaeal feast/famine regulatory protein, DM1 (pot1216151)

Abstract

Effects of types of amino acids on assembling of a feast/famine regulatory protein (FFRP), pot1216151 (DM1) from the hyperthermophilic archaeon Pyrococcus sp. OT3, was studied using its two fractions; more assembled (A) and more disassembled (D). The amino acid isoleucine was found to shift the equilibrium of both A and D to more assembling states. Valine showed weaker effects of assembling DM1. While seven other amino acids showed effects of disassembling DM1 in both A and D with different degrees, thereby creating an order, I/V/(L, T, F, A)/R/M/C, from the most assembling amino acid isoleucine to the most disassembling one cysteine. When one of the top three amino acids in this sequence, isoleucine, valine and leucine, was added to mother solutions yielding crystals of DM octamers, the crystals lost polarization, suggesting disordering inside. Some other metabolic intermediates, oxaloacetic acid, 2-oxoglutaric acid, and L-malic acid, also showed disassembling effects. On the basis of these findings, molecular interactions of DM1 and ligands, and their possible roles for metabolic regulation are discussed.


(Communicated by Masanori OTSUKA, M.J.A.)