title: Purification of a small receptor-binding peptide from the central region of the colicin E1 molecule.
abstract: An Mr = 16,000 receptor-binding fragment of colicin E1 has been obtained by cyanogen bromide digestion of colicin E1. The purified 16-kDa fragment shows binding properties similar to those of an Mr = 38,000 colicin E1 receptor-binding fragment generated by thermolysin treatment. Treatment of the 38-kDa fragment with cyanogen bromide also yields the 16-kDa fragment. By comparing the NH2-terminal amino acid sequence of the 16-kDa fragment with the known colicin E1 sequence, the receptor-binding fragment can be shown to occupy the central region of the colicin molecule, extending from residue 231 to 370. It is inferred that the 16-kDa fragment binds efficiently to the colicin receptor because it is able to protect sensitive cells against the lethal effects of colicins E1 and E2 and, when pre-adsorbed to the cell, to physically displace colicin E1. Unlike the 38-kDa receptor-binding fragment, the 16-kDa fragment was found to be devoid of channel-forming ability previously shown to be associated with the COOH-terminal region of the colicin E1 polypeptide.
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D003087:Colicins / Q000032:analysis*; D003488:Cyanogen Bromide; D004926:Escherichia coli; D029968:Escherichia coli Proteins; D008970:Molecular Weight; D010446:Peptide Fragments / Q000302:isolation & purification* / Q000378:metabolism; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D003087:Colicins; D029968:Escherichia coli Proteins; D010446:Peptide Fragments; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; C028593:colicin receptor, E coli; D003488:Cyanogen Bromide