Molecular characterization of L. interrogans ClpP1, ClpP2, and ClpX. (A) Cloning and overexpression of ClpPs
and ClpX in E. coli. The Coomassie-blue
stained 12% SDS-polyacrylamide gel showing the resolved protein lysates
of E. coli cells overexpressing LeptospiraclpP1 (pET23a-clpP1), clpP2 (pET23a-clpP2), and clpX (pET23a-clpX),
after induction with (+) or without (−) 1 mM IPTG. (B) The
affinity-purified Leptospira recombinant
proteins. The Ni-NTA affinity-purified rClpP1 (∼23 kDa), rClpP2
(∼22 kDa), and rClpX (∼47 kDa) proteins were resolved
on 12% SDS-polyacrylamide gel and stained with Coomassie-blue. In
image (A,B), M denotes the standard protein molecular size marker
(in kDa). (C,D) Western blot of native ClpP1 and ClpP2 of Leptospira, respectively. The native ClpP1 and ClpP2
in Leptospira lysates were detected
in pathogenic strains (serovar Lai and Copenhageni) but not in the
nonpathogenic strain (serovar Patoc) using the primary antibodies
generated against rClpP1 and rClpP2, respectively. Native and recombinant
ClpP isoforms were detected at a similar molecular size.