Kdp is an ATP-driven potassium transport system of Escherichia coli. It consists of three proteins, KdpA, KdpB and KdpC, encoded by the three genes of the kdpABC operon. Expression of the kdpABC operon is under the control of the two products of the adjacent kdpDE operon. Kdp is functionally similar to transport ATPases with an acyl-phosphate intermediate. The sequence of KdpB is homologous to the Ca-ATPase of sarcoplasmic reticulum. Major emphasis remains on genetic approaches: 1. Clone kdpABC operon behind a strong, controllable promoter. 2. Isolate, characterize and sequence mutations which alter but do not abolish Kdp function. Mutations which reduce affinity for K are under study; many more such mutations will be investigated. Mutations whose primary effect is to reduce the Vmax of transport will also be studied. 3. KdpA has been identified as having a major role in forming the K binding site of Kdp. The sequence of KdpA suggests it crosses the membrane many times. Topological will be performed to identify which parts of KdpA are exposed internally, which are exposed externally and which are in the membrane. 4. Determine subunit interactions in the functional Kdp complex. 5. Identify and characterize the products of the kdpDE operon. 6. Characterize the kdpABC promoter: sequence the promoter region and determine the site of transcription initiation. 7. Clone kdpDE behind a strong, controllable promoter. 8. Study properties of the proteins encoded by the kdpDE operon; attempt to define their roles in regulation. This project has beniffted from collaboration with Karlheinz Altendorf (Univ. of O nabruck, West Germany) for several years. This collaboration continues; work to be done mainly or exclusively in Osnarbruck, includes 9. Purification to homogeneity of Kdp. 10. Determination of the N-terminal sequence of KdpB; determination of the C-terminal residues of KdpA, KdpB and KdpC.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM022323-13
Application #
3271088
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1978-09-01
Project End
1988-08-31
Budget Start
1987-09-01
Budget End
1988-08-31
Support Year
13
Fiscal Year
1987
Total Cost
Indirect Cost
Name
University of Chicago
Department
Type
Schools of Medicine
DUNS #
225410919
City
Chicago
State
IL
Country
United States
Zip Code
60637
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Brandon, L; Dorus, S; Epstein, W et al. (2000) Modulation of KdpD phosphatase implicated in the physiological expression of the kdp ATPase of Escherichia coli. Mol Microbiol 38:1086-92
Gassel, M; Siebers, A; Epstein, W et al. (1998) Assembly of the Kdp complex, the multi-subunit K+-transport ATPase of Escherichia coli. Biochim Biophys Acta 1415:77-84
Buurman, E T; Kim, K T; Epstein, W (1995) Genetic evidence for two sequentially occupied K+ binding sites in the Kdp transport ATPase. J Biol Chem 270:6678-85
Altendorf, K; Siebers, A; Epstein, W (1992) The KDP ATPase of Escherichia coli. Ann N Y Acad Sci 671:228-43
Polarek, J W; Williams, G; Epstein, W (1992) The products of the kdpDE operon are required for expression of the Kdp ATPase of Escherichia coli. J Bacteriol 174:2145-51
Walderhaug, M O; Polarek, J W; Voelkner, P et al. (1992) KdpD and KdpE, proteins that control expression of the kdpABC operon, are members of the two-component sensor-effector class of regulators. J Bacteriol 174:2152-9
Epstein, W (1992) Kdp, a bacterial P-type ATPase whose expression and activity are regulated by turgor pressure. Acta Physiol Scand Suppl 607:193-9
Epstein, W; Walderhaug, M O; Polarek, J W et al. (1990) The bacterial Kdp K(+)-ATPase and its relation to other transport ATPases, such as the Na+/K(+)- and Ca2(+)-ATPases in higher organisms. Philos Trans R Soc Lond B Biol Sci 326:479-86;discussion 486-7
Walderhaug, M O; Litwack, E D; Epstein, W (1989) Wide distribution of homologs of Escherichia coli Kdp K+-ATPase among gram-negative bacteria. J Bacteriol 171:1192-5