Hl. Qi et al., EXPRESSION OF LARGE AMOUNTS OF NEISSERIAL PORIN PROTEINS IN ESCHERICHIA-COLI AND REFOLDING OF THE PROTEINS INTO NATIVE TRIMERS, Infection and immunity, 62(6), 1994, pp. 2432-2439
Porins from different neisserial strains and species have been shown t
o have differences in both primary amino acid sequence and biophysical
characteristics as observed by functional assays. A closer examinatio
n of how the changes in the primary amino acid sequence of Neisseria p
orin molecules correlate with these observed biophysical changes has b
een impeded by the inability to easily manipulate the cloned porin gen
es by modern molecular techniques and then obtain enough of the expres
sed modified porin protein to purify and use in these biophysical func
tional assays. In this report, we describe a method by which the genes
encoding three different porin proteins, lacking their neisserial pro
moter and signal sequences, were cloned into an expression plasmid and
transformed into Escherichia coli. Upon induction, large amounts of t
he porin proteins were produced. The expressed porin proteins were the
n manipulated to regenerate their native trimer structure and purified
by standard protein chemistry. Sufficient purified recombinant porin
protein was obtained for further antigenic as well as biophysical char
acterization. This sets the stage for the biophysical characterization
of these neisserial porin proteins in more detail.