Switch to
| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
36
|
| pubmed:dateCreated |
1994-1-27
|
| pubmed:abstractText |
A carboxyl group of Asp-285 is essential for tetracycline/H+ antiport mediated by the transposon Tn10-encoded metal-tetracycline/H+ antiporter (TetA) of Escherichia coli (Yamaguchi, A., Akasaka, T., Ono, N., Someya, Y., Nakatani, M., and Sawai, T. (1992) J. Biol. Chem. 267, 7490-7498). Spontaneous tetracycline resistance revertants were isolated from E. coli cells carrying the Asn-285 mutant tetA gene. All of the revertants were due to the second-site mutation at codon 220 of GCG (Ala) to GAG (Glu). The Km value of the tetracycline transport mediated by the revertant TetA protein was about 4-fold higher than that of the wild-type, indicating that the revertant is a low affinity mutant. A Glu-220 and Asn-285 double mutant constructed by site-directed mutagenesis showed the same properties as the revertants, confirming that the mutation of Ala-220 is solely responsible for the suppression. The Asp-220 mutation of the Asn-285 mutant resulted in a lower level of restoration of the tetracycline resistance and the transport activity than in the case of the Glu-220 mutation. A single mutation replacing Ala-220 with Glu or Asp caused about a 2-4-fold decrease in the tetracycline resistance, but no crucial change in the transport activity. It is not likely that Glu-220 is required for a charge-neutralizing salt bridge because an unpaired negative charge in a Glu-220 or Asp-220 single mutant did not cause a serious change in the activity. An alternative explanation is reasonable; Asp-285 directly contributes to the binding of a cationic substrate, metal-tetracycline chelation complex, or proton, and an acidic residue at position 220 can take over the role of Asp-285.
|
| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Alanine,
http://linkedlifedata.com/resource/pubmed/chemical/Amino Acids,
http://linkedlifedata.com/resource/pubmed/chemical/Antiporters,
http://linkedlifedata.com/resource/pubmed/chemical/Asparagine,
http://linkedlifedata.com/resource/pubmed/chemical/Aspartic Acid,
http://linkedlifedata.com/resource/pubmed/chemical/Bacterial Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/DNA, Bacterial,
http://linkedlifedata.com/resource/pubmed/chemical/DNA Transposable Elements,
http://linkedlifedata.com/resource/pubmed/chemical/Glutamates,
http://linkedlifedata.com/resource/pubmed/chemical/Glutamic Acid,
http://linkedlifedata.com/resource/pubmed/chemical/Repressor Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Tetracycline,
http://linkedlifedata.com/resource/pubmed/chemical/tetA protein, Bacteria
|
| pubmed:status |
MEDLINE
|
| pubmed:month |
Dec
|
| pubmed:issn |
0021-9258
|
| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:day |
25
|
| pubmed:volume |
268
|
| pubmed:geneSymbol |
tet
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
26990-5
|
| pubmed:dateRevised |
2006-11-15
|
| pubmed:meshHeading |
pubmed-meshheading:7903301-Alanine,
pubmed-meshheading:7903301-Amino Acid Sequence,
pubmed-meshheading:7903301-Amino Acids,
pubmed-meshheading:7903301-Antiporters,
pubmed-meshheading:7903301-Asparagine,
pubmed-meshheading:7903301-Aspartic Acid,
pubmed-meshheading:7903301-Bacterial Proteins,
pubmed-meshheading:7903301-Base Sequence,
pubmed-meshheading:7903301-Biological Transport,
pubmed-meshheading:7903301-DNA, Bacterial,
pubmed-meshheading:7903301-DNA Transposable Elements,
pubmed-meshheading:7903301-Escherichia coli,
pubmed-meshheading:7903301-Glutamates,
pubmed-meshheading:7903301-Glutamic Acid,
pubmed-meshheading:7903301-Kinetics,
pubmed-meshheading:7903301-Molecular Sequence Data,
pubmed-meshheading:7903301-Mutagenesis, Site-Directed,
pubmed-meshheading:7903301-Plasmids,
pubmed-meshheading:7903301-Protein Structure, Secondary,
pubmed-meshheading:7903301-Repressor Proteins,
pubmed-meshheading:7903301-Suppression, Genetic,
pubmed-meshheading:7903301-Tetracycline
|
| pubmed:year |
1993
|
| pubmed:articleTitle |
Second-site mutation of Ala-220 to Glu or Asp suppresses the mutation of Asp-285 to Asn in the transposon Tn10-encoded metal-tetracycline/H+ antiporter of Escherichia coli.
|
| pubmed:affiliation |
Division of Microbial Chemistry, Faculty of Pharmaceutical Sciences, Chiba University, Japan.
|
| pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
|