PMID:9236129
| Citation |
Wu, J and Kaback, HR (1997) Helix proximity and ligand-induced conformational changes in the lactose permease of Escherichia coli determined by site-directed chemical crosslinking. J. Mol. Biol. 270:285-93 |
|---|---|
| Abstract |
N and C-terminal halves of lactose permease, each with a single-Cys residue, were co-expressed, and crosslinking was studied. Iodine or N,N'-o-phenylenedimaleimide (o-PDM; rigid 6 A), crosslinks Asn245 Cys (helix VII) and Ile52 --> Cys or Ser53 --> Cys (helix II). N,N'-p-phenylenedimaleimide (p-PDM; rigid 10 A) crosslinks the 245/53 Cys pair weakly, but does not crosslink 245/52, and 1,6-bis-maleimidohexane (BMH; flexible 16 A) crosslinks both pairs less effectively than o-PDM. Thus, 245 is almost equidistant from 52 and 53 by up to about 6 A. BMH or p-PDM crosslinks Gln242 --> Cys and Ser53 --> Cys, but o-PDM is ineffective, indicating that distance varies by up to 10 A. Ligand binding increases crosslinking of 245/53 with p-PDM or BMH, has little effect with o-PDM and decreases iodine crosslinking. Similar effects are observed with 245/52. Ligand increases 242/53 crosslinking with p-PDM or BMH, but no crosslinking is observed with o-PDM. Therefore, ligand induces a translational or scissors-like displacement of the helices by 3-4 A. Crosslinking 245/53 inhibits transport indicating that conformational flexibility is important for function. |
| Links |
PubMed Online version:10.1006/jmbi.1997.1099 |
| Keywords |
Amino Acid Sequence; Antibodies, Monoclonal/pharmacology; Biological Transport; Cross-Linking Reagents/pharmacology; Cysteine/chemistry; Escherichia coli/enzymology; Escherichia coli/immunology; Escherichia coli Proteins; Ligands; Membrane Transport Proteins/chemistry; Membrane Transport Proteins/immunology; Membrane Transport Proteins/metabolism; Monosaccharide Transport Proteins; Mutagenesis, Site-Directed; Protein Conformation/drug effects; Protein Structure, Secondary/drug effects; Symporters |
| edit table |
Significance
You can help EcoliWiki by summarizing why this paper is useful
Useful Materials and Methods
You can help Ecoliwiki by describing the useful materials (strains, plasmids, antibodies, etc) described in this paper.
Annotations
<annotationlinks/>
EcoliWiki Links
Add links to pages that link here (e.g. gene, product, method pages)
References
See Help:References for how to manage references in EcoliWiki.
