Linked Life Data

1691183

Source:http://linkedlifedata.com/resource/pubmed/id/1691183

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
1990-5-24
pubmed:abstractText
Colicin E1 is a soluble, bacteriocidal protein that forms voltage-gated channels in planar lipid bilayers. The channel-forming region of the 522-amino acid protein is near the COOH terminus, and contains a 35-amino acid hydrophobic segment which is presumed to be important in interacting with the membrane. We have used site-directed mutagenesis in the region immediately upstream from the hydrophobic segment to construct several functional colicin mutants in which a wild-type residue was replaced with a cysteine. We also replaced the only naturally occurring cysteine in the molecule, Cys-505, with alanine, so that synthetically introduced cysteines could unambiguously serve as targets for chemical modification. All of the replacements reported here (at positions 449, 459, 473, 505, and some combinations) resulted in a channel that had an ion selectivity (K+ versus Cl-) identical to wild type at low pH. At higher pH, however, one of these mutations, which replaced the negatively charged aspartate at position 473 (the upstream boundary of the hydrophobic segment), resulted in a channel that was less cation-selective than was wild type. When the introduced Cys-473 was reacted with iodoacetic acid, which inserted a COOH group close to the position of the missing aspartate COOH, wild-type ion selectivity was restored, suggesting that the greater cation selectivity of the wild-type channel was directly produced by the negative charge at Asp-473. By comparing the ion selectivity of the Cys-473 mutant channel to that of the wild type as a function of the pH on the cis and trans sides of the membrane, it was possible to locate residue 473 close to the cis side. Locating in this manner the positions in the channel of particular residues places important constraints on channel model building.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
265
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
6984-91
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed-meshheading:1691183-Amino Acid Sequence, pubmed-meshheading:1691183-Base Sequence, pubmed-meshheading:1691183-Colicins, pubmed-meshheading:1691183-Escherichia coli, pubmed-meshheading:1691183-Escherichia coli Proteins, pubmed-meshheading:1691183-Genes, Bacterial, pubmed-meshheading:1691183-Hydrogen-Ion Concentration, pubmed-meshheading:1691183-Iodoacetamide, pubmed-meshheading:1691183-Iodoacetates, pubmed-meshheading:1691183-Iodoacetic Acid, pubmed-meshheading:1691183-Ion Channels, pubmed-meshheading:1691183-Kinetics, pubmed-meshheading:1691183-Lipid Bilayers, pubmed-meshheading:1691183-Membrane Potentials, pubmed-meshheading:1691183-Molecular Sequence Data, pubmed-meshheading:1691183-Mutation, pubmed-meshheading:1691183-Oligonucleotide Probes, pubmed-meshheading:1691183-Plasmids, pubmed-meshheading:1691183-Receptors, Cell Surface, pubmed-meshheading:1691183-Receptors, Immunologic, pubmed-meshheading:1691183-Restriction Mapping
pubmed:year
1990
pubmed:articleTitle
Alteration of the pH-dependent ion selectivity of the colicin E1 channel by site-directed mutagenesis.
pubmed:affiliation
Department of Physiology & Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.