The Interaction Between Lipoprotein (a) And Recombinant Dihydrolipoamide Dehydrogenase Derived From Pseudomonas Aeruginosa

Dihydrolipoamide dehydrogenase (Lpd) is exposed at P. aeruginosa surface and binds to human plasminogen (Pig). Pig via its lysine binding site binds to Lpd on the surface of P. aeruginosa. Apolipoprotein(a) [Apo(a)] which is one component of lipoprotein(a) [Lp(a)] is highly similar to Pig and both of them include Kringle (K) which contain LBS. Therefore we hypothesized that Lp(a) might bind to Lpd and competitively inhibiting the binding of Pig to Lpd.To test our hypothesis, the recombinant rLpd and its mutants (rLpd-K476A, rLpd-K477A, rLpdΔKKR) were expressed and purified from E. coli BL21. The interactions between recombinant proteins with Pig, Lp(a) and LDL were investigated by enzyme-linked immunosorbent assay (ELISA) and affinity chromatography-binding assay followed by Western blot analysis. The results indicated that rLpd could specifically bind to Lp(a) but not to LDL and the binding of rLpd to Lp(a) could be significantly inhibited by EACA. It indicated that Lp(a) via its LBS in Apo(a) binds to rLpd. The binding capacity of rLpdAKKR is significantly lower than that of rLpd implying that 476th and 477th lysine residues of Lpd were main binding sites. Lp(a) could significantly inhibit the binding of Pig to Lpd. It indicated that the interaction of rLpd with Lp(a) is similar to Pig.