ISSN:
0091-7419
Schlagwort(e):
transport
;
induction of influx
;
LacY permease
;
β-D-galactosidase
;
facilitated diffusion
;
Life Sciences
;
Molecular Cell Biology
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Biologie
,
Chemie und Pharmazie
,
Medizin
Notizen:
Strains of Escherichia coli K12 were constructed for the specific purpose of evaluating the inducibility of the influx mechanism controlled by the lacY gene. These strains are heteromerodiploids characterized by a high and relatively constant level of β-D-galactosidase which is not affected significantly by induction of the Lac operon. These properties were obtained by introducing episomal lacI+,Oc,Z+,Y- genes into the cells. In these merodiploids the rate of o-nitrophenyl-β-D-galactopyranoside (ONPG) hydrolysis of extracted cells is 50-times that of intact cells. This difference indicates that the rate limiting step in the ONPG hydrolysis by intact cells is influx.Using a set of merodiploids with and without the LacY transport system, we were able to demonstrate a specific induction of ONPG influx. However, the increase in influx due to induction was only 3.5-fold as compared to the 40-fold increase observed when the LacY permease was measured by intracellular accumulation of [14C] TMG.
Zusätzliches Material:
2 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/jss.400070104
