The C-terminal cysteine of turbot Scophthalmus maximus translationally controlled tumour protein plays a key role in antioxidation and growth-promoting functions.

The translationally controlled tumour protein (TCTP) of turbot Scophthalmus maximus (SmTCTP) contains only one cysteine (Cys(170)) at the C-terminal end. The biological role of this C-terminal Cys(170) in the antioxidation and growth-promoting functions of SmTCTP was examined by site-directed mutation of C170A (Cys(170)Ala(170)). It was found that C170A mutation not only obviously decreased the antioxidation capacity of the mutant-smtctp-transformed bacteria exposed to 022 mM hydrogen peroxide, but also significantly interrupted the normal growth and survival of the mutant-smtctp-transformed bacteria and flounder Paralichthys olivaceus gill (FG) cells, indicating a key role played by Cys(170) in the antioxidation and growth-promoting functions of SmTCTP. This study also suggested that the self-dimerization or dimerization with other interacting proteins is critical to the growth-promoting function of SmTCTP. (C) 2013 The Fisheries Society of the British Isles