부산대학교 도서관

Background: Arginine deiminase (ArcA) has been speculated to facilitate the intracellular survival of Streptococcus suis under acidic conditions. However, the physical and biological properties and function of SS2 -ArcA have not yet been elucidated. Methods: Recombinant SS2 -ArcA (r SS2 -ArcA) was expressed and purified using Ni-NTA affinity chromatography. Under various pH and temperature conditions, the enzymatic properties of purified r SS2 -ArcA and crude native SS2 -ArcA were determined. Results: The SS2-arcA-deduced amino acid sequence contained a conserved catalytic triad (Cys399-His273-Glu218). The optimum temperature and pH of 47-kDa r SS2 -ArcA and crude native SS2-ArcA were 42 ° C and pH 7.2. The r SS2 -ArcA and crude native SS2 -ArcA were stable for 3 h at 4 and 25 ° C, respectively. The pH stability and dependency tests suggested that r SS2 -ArcA and crude native SS2 -ArcA were functionally active in acidic conditions. The L -arginine substrate binding affinity ( Km) values of r SS2 -ArcA (specific activity 16.00 U/mg) and crude native SS2-ArcA (specific activity 0.23 U/mg) were 0.058 and 0.157 m M, respectively. r SS2 -ArcA exhibited a weak binding affinity with the common ArcA inhibitors L -canavanine and L -NIO. Furthermore, the partial inactivation of SS2 -ArcA significantly impaired the viability and growth of SS2 at pH 4.0, 6.0, and 7.5. Conclusions: This study profoundly demonstrated the involvement of ArcA enzymatic activity in S. suis survival under acidic conditions. [ABSTRACT FROM AUTHOR]