M. Sahintoth et al., ACTIVE-TRANSPORT BY THE CSCB PERMEASE IN ESCHERICHIA-COLI K-12, Biochemical and biophysical research communications, 208(3), 1995, pp. 1116-1123
The cscB gene encoding a putative sucrose permease from Escherichia co
li EC3132 [Bockmann, J., Heuel, H. & Lengeler, J. W. (1992) Mol. Gen.
Genet. 235, 22-32] was placed under control of the lacZ promoter/opera
tor and overexpressed. Cells of E. coli K-12 expressing cscB gene prod
uct from a high copy number plasmid accumulate sucrose against a conce
ntration gradient with an apparent K-m of about 1 mM and a V-max of ap
proximately 23 nmol/min/mg protein. In contrast, transport of lactose
or melibiose is not observed. Epitope-tagging and immunological analys
is reveal that concomitant with increased transport activity, a protei
n with an apparent M(r) of 33-34 kDa appears in the cytoplasmic membra
ne. The results provide direct support for the contention that the csc
B gene encodes a sucrose permease and provide the basis for further mo
lecular analysis. (C) 1995 Academic Press, Inc.