The interaction between Lipoprotein(a) and recombinant inosine 5'-monophosphate dehydrogenase derived from Staphylococcus aureus

Abstract:

Inosine 5'-monophosphate dehydrogenase (IMPDH) is one of plasminogen (Plg) receptors on the surface of Staphylococcus aureu (S. aureus). Plg through its lysine binding sites (LBS) binds to IMPDH. Apolipoprotein(a) [Apo(a)], which is one component of Lipoprotein(a) [Lp(a)], has a high homology with Plg and both of them contain LBS in their Kringle (K) domains, and a strong LBS is identified in KIV10 of Apo(a). Therefore, we previously reported that Lp(a) might bind to Plg receptor on the surface of S. aureus, subsequently competitively inhibiting the interaction of S. aureus with Plg. To further test our hypothesis, the IMPDH gene of S. aureus was cloned into pASK-IBA37 and the re-combinant IMPDH(rIMPDH) was expressed in E. coli BL21. The interaction between rIMPDH and Lp(a) was investigated by enzyme-linked immunosorbent assay (ELISA), and affinity chromatogra-phy-binding assay followed by Western blotting. The results indicated that rIMPDH could specifically bind to purified Lp(a) and rKIV10, and the lysine analog EACA inhibited the binding. Unexpectedly, Lp(a) and rKIV10 did not significantly inhibit the interaction between rIMPDH and Plg.