Effects of histidine aminonia-lyase on the biological characteristics and pathogenicity of Vibrio parahaemolyticus

Abstract:

As the first metabolic enzyme in the histidine metabolic pathway, histidine aminonia-lyase (HutH) controls the metabolism of histidine in bacteria. HutH is highly conserved in most bacteria and participates in the balance of bacterial energy metabolism.[Objective] To investigate the effects of HutH on the biological characteristics and pathogenicity of Vibrio parahaemolyticus. [Methods] The hutH gene-deleted mutant ΔhutH and the complementary strain CΔhutH were constructed by homologous recombination. The effects of HutH on the growth characteristics, histidine utilization ability, histidine metabolism related gene expression level, motility, biofilm, environmental tolerance, cytotoxicity and mouse toxicity of V.parahaemolyticus were researched. [Results] Compared with wild strains, the deletion of hutH gene did not affect the growth characteristics, acid and alkali tolerance, salt tolerance and swarming ability of V.parahaemolyticus. But the growth of ΔhutH was significantly inhibited in M9-limited medium with histidine as the only carbon source. In addition, we confirmed that the deletion of hutH significantly decreased the transcription level of histidine metabolism related genes in hut operon and increased the expression level of the VP0889 gene. The deletion of hutH resulted in the decrease in biofilm formation ability, swimming ability, toxicity to HeLa cells and mortality to institution of cancer research female mice. [Conclusion] This study shows that the deletion of hutH affects the ability of V.parahaemolyticus to metabolize histidine, and it is the first time to confirm that HutH plays an important role in the biofilm formation, motility and toxicity toward mice of V.parahaemolyticus, which provides ideas for bacterial prevention and control by regulating histidine metabolism.

Key words:Vibrio parahaemolyticus;histidine aminonia-lyase;biofilm;motility;pathogenicity