Active transport by the CscB permease in Escherichia coli K-12.
The cscB gene encoding a putative sucrose permease from Escherichia coli EC3132 [Bockmann, J., Heuel, H. & Lengeler, J.W. (1992) Mol. Gen. Genet. 235, 22-32] was placed under control of the lacZ promoter/operator and overexpressed. Cells of E. coli K-12 expressing cscB gene product from a high copy number plasmid accumulate sucrose against a concentration gradient with an apparent Km of about 1 mM and a Vmax of approximately 23 nmol/min/mg protein. In contrast, transport of lactose or melibiose is not observed. Epitope-tagging and immunological analysis reveal that concomitant with increased transport activity, a protein with an apparent M(r) of 33-34 kDa appears in the cytoplasmic membrane. The results provide direct support for the contention that the cscB gene encodes a sucrose permease and provide the basis for further molecular analysis.
Sahin-Tóth
M
M
Howard Hughes Medical Institute, Department of Physiology, University of California, Los Angeles 90095-1662.
Frillingos
S
S
Lengeler
J W
JW
Kaback
H R
HR
D001483:Base Sequence; D001693:Biological Transport, Active; D002462:Cell Membrane / Q000201:enzymology; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry / Q000378:metabolism; D000939:Epitopes / Q000032:analysis; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins; D015870:Gene Expression; D005798:Genes, Bacterial; D007700:Kinetics; D026901:Membrane Transport Proteins / Q000096:biosynthesis / Q000378:metabolism*; D008969:Molecular Sequence Data; D010957:Plasmids; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D013395:Sucrose / Q000378:metabolism; D001616:beta-Galactosidase / Q000235:genetics
D004269:DNA, Bacterial; D000939:Epitopes; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; C056379:cscB protein, E coli; D013395:Sucrose; D001616:beta-Galactosidase