A protein bodyguard – private security in the defense against oxidation
To endure oxidative conditions, RTCB (bottom half) co-evolved with the dedicated protector PYROXD1 (depicted holding a shield). PYROXD1 utilizes the flavin molecule (represented in orange) and the cofactor NAD(P)+ (red) to shield RTCB from oxygen and reactive oxygen species (air bubbles), which would together with copper ions (violet balls) cause RTCB inactivation, abrogating tRNA biogenesis and stress response. (c) Tanja Asanovic
Oxidative stress is a biochemical condition in which the levels of oxidant molecules exceed the level of reductants (also known as anti-oxidants) in an organism. High concentrations of oxidants can alter the activity of enzymes and damage lipids, proteins and nucleic acids. Reporting in Molecular Cell, the lab of Javier Martinez reveals a novel and surprising mechanism of how an essential enzyme protects itself from oxidative stress. The tRNA ligase RTCB evolved with another protein whose sole purpose is to protect RTCB from oxidation. This protein, called PYROXD1, is linked to myopathies in humans and, paradoxically, uses a key cellular oxidant, NADP+, to protect its partner.