Environment-induced conformational and functional changes of l-2-haloacid dehalogenase

• The environment-induced conformational and functional changes of l-2-haloacid dehalogenase were firstly studied by CD spectroscopy.
• Decreased α-helix and increased β-sheet contents were observed along with activity loss caused by pH, temperature and inhibitors.
• More than 65.0% of the enzyme activity could be remained if its α-helix content was over 12.0%.
• The maintenance of α-helical structure is indispensable to the enzymatic activity, while β-sheet increase restricts the activity.

2-Haloacid dehalogenases have been highly studied due to their potential applications in chemical industries and bioremediation. Although biochemical and structural characterizations of the enzyme have been detailed, no information was available regarding environmental effects on the structure–function relationship. Here, circular dichroism spectroscopy (CD) was used to investigate the correlation between changes on the conformation and the function of l-2-haloacid dehalogenase (HadL AJ1) from the Pseudomonas putida induced by the environmental factors. Decreased α-helix and increased β-sheet contents were observed in the structure of HadL AJ1 along with activity losses caused by pH, temperature and inhibitors. Regardless of which factor above-mentioned existed, more than 65.0% of HadL AJ1 activity could be remained if its α-helix content was over 12.0%. The maintenance of α-helical structure in HadL AJ1 was indispensable to its catalysis, while β-sheet increase restricts its activity. This study revealed the variation of enzymatic activity due to environmental conditions resulting in structural changes monitored by CD, which contributed to rational modification and was instructive for predicting changes of the enzymatic activity during application.