Secreted Expression of Thymosin β4 from Pinctada fucata in Pichia pastoris and Its Biological Activity

The aim of this study was to achieve the high secretion and expression of thymosin β4 derived from <i>Pinctada fucata</i> in <i>Pichia pastoris</i>, as well as to investigate its antibacterial properties and biological effects in promoting wound healing. The recombinant thymosin β4 protein (rTβ4) exhibited no hemolytic activity on rabbit red blood cells and demonstrated significant antibacterial activity against methicillin-resistant <i>Staphylococcus aureus</i> (MRSA), with a minimum inhibitory concentration (MIC) of 25 μg/mL. It effectively inhibited bacterial growth and disrupted the cell wall and membrane structure of the bacteria. In the Sprague Dawley (SD) rat wound healing model, the wound healing rate in the rTβ4 treatment groups (at concentrations of 12.5 and 25 μg/mL) was significantly higher than that in the control group (<i>p</i> < 0.05), and the healing effect was comparable to that of the positive control group (Kangfu Xin solution, KFX). The histopathological study demonstrated that rTβ4 could reduce the infiltration of inflammatory cells and promote the proliferation and re-epithelialization of granulation tissue. In conclusion, this study successfully achieved the high expression of thymosin β4 derived from <i>Pinctada fucata</i> in <i>Pichia pastoris</i> and validated its antibacterial and wound healing potential through both In vitro and In vivo experiments.