The maltose transport system of Escherichia coli is a well-characterized member of the ATP binding cassette transporter superfamily. Members of this family share sequence similarity surrounding two short sequences (the Walker A and B sequences) which constitute a nucleotide binding pocket. It is likely that the energy from binding and hydrolysis of ATP is used to accomplish the translocation of substrate from one location to another.
View Article and Find Full Text PDFP1 plasmid encodes a cis-acting centromere analog, parS, and two Par proteins that together stabilize plasmids by partitioning them to daughter bacteria. We infected immune bacteria with bacteriophage lambda into which parS had been inserted. The presence of P1 Par proteins in the infected cells was found to delay the appearance of cells cured of the nonreplicating, extrachromosomal lambda-parS DNA.
View Article and Find Full Text PDFActive accumulation of maltose and maltodextrins by Escherichia coli depends on an outer-membrane protein. LamB, a periplasmic maltose-binding protein (MalE, MBP) and three inner-membrane proteins, MalF, MalG and MalK. MalF and MalG are integral transmembrane proteins, while MalK is associated with the inner aspect of the cytoplasmic membrane via an interaction with MalG.
View Article and Find Full Text PDFIn wild-type Escherichia coli the activity of the maltose transport system is dependent on a periplasmic maltose-binding protein. It has been possible, however, to isolate mutants in which transport activity is mediated by the membrane components of the system and is no longer dependent on the periplasmic binding protein. In this manuscript we show that in these binding protein-independent strains, p-nitrophenyl-alpha-maltoside is a potent inhibitor of maltose transport.
View Article and Find Full Text PDFWe isolated mutants of Escherichia coli in which the maltose-binding protein (MBP) is no longer required for growth on maltose as the sole source of carbon and energy. These mutants were selected as Mal+ revertants of a strain which carries a deletion of the MBP structural gene, malE. In one class of these mutants, maltose is transported into the cell independently of MBP by the remaining components of the maltose system.
View Article and Find Full Text PDF