Open AccessInhibition of cytotoxicity by the N he cytotoxin of B acillus cereus through the interaction of dodecyl maltoside with the NheB component
Author(s) -
Phung Danh,
Granum Per Einar,
Dietrich Richard,
Märtlbauer Erwin,
Hardy Simon P.
Publication year - 2012
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2012.02538.x
Subject(s) - bacillus cereus , enterotoxin , cytotoxicity , escherichia coli , vero cell , incubation , biochemistry , sodium dodecyl sulfate , haemolysis , biology , micelle , chemistry , chromatography , bacteria , in vitro , organic chemistry , genetics , aqueous solution , gene , immunology
Nhe (‘nonhaemolytic enterotoxin’) is a three‐component cytotoxin implicated in the pathogenesis of diarrhoea by B acillus cereus . N he forms pores in pure lipid bilayers, but the function of the individual components ( NheA , NheB and NheC ) remains unclear. NheB and NheC are structural homologues of C ly A , a pore‐forming cytotoxin of E scherichia coli . The non‐ionic detergent dodecyl maltoside ( DDM ) has been shown to inhibit haemolysis of C ly A . We used DDM as a probe to examine the response of the Nhe proteins to DDM micelles. At its critical micellar concentration (0.2 mM), DDM inhibited propidium uptake by the native N he complex in V ero and H T29 cell suspensions. Pre‐incubation of NheC with DDM did not inhibit cytotoxicity. NheB exhibited marked changes in 1‐anilinonaphthalene‐8‐sulphonic acid ( ANS ) fluorescence after pre‐exposure to DDM . Pre‐incubation of NheB with DDM resulted in large molecular weight complexes as detected by size exclusion chromatography and diffusion through sized dialysis membranes and prevented binding of NheB to V ero cell monolayers. These data support a model in which conformational changes and oligomerization of NheB are prerequisite events in the process of pore formation.