Different foci for the regulation of the activity of the KefB and KefC glutathione-gated K+ efflux systems

L S Ness, I R Booth

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

KefB and KefC are glutathione-gated K+ efflux systems in Escherichia coti, and the proteins exhibit strong similarity at the level of both primary sequence and domain organization. The proteins are maintained closed by glutathione and are activated by binding of adducts formed between glutathione and electrophiles. By construction of equivalent mutations in each protein, this study has analyzed the control over inactive state of the proteins. A UV-induced mutation in KefB, L75S, causes rapid spontaneous K+ efflux but has only a minor effect on K+ efflux via KefC. Similarly amino acid substitutions that cause increased spontaneous activity in RefC have only small effects in RefB. Exchange of an eight amino acid region from KefC (HALESDIE) with the equivalent sequence from KefB (HELETAID) has identified a role for a group of acidic residues in controlling KefC activity. The mutations HELETALD and L74S in KefC act synergistically, and the activity of the resultant protein resembles that of KefB. We conclude that, despite the high degree of sequence similarity, KefB and KefC: exhibit different sensitivities to the same site-specific mutations.

Original languageEnglish
Pages (from-to)9524-9530
Number of pages7
JournalThe Journal of Biological Chemistry
Volume274
Publication statusPublished - 1999

Keywords

  • ESCHERICHIA-COLI
  • POTASSIUM CHANNELS
  • ACTIVATION
  • CLONING
  • TRANSPORT
  • GENE

Cite this

Different foci for the regulation of the activity of the KefB and KefC glutathione-gated K+ efflux systems. / Ness, L S ; Booth, I R .

In: The Journal of Biological Chemistry, Vol. 274, 1999, p. 9524-9530.

Research output: Contribution to journalArticle

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T1 - Different foci for the regulation of the activity of the KefB and KefC glutathione-gated K+ efflux systems

AU - Ness, L S

AU - Booth, I R

PY - 1999

Y1 - 1999

N2 - KefB and KefC are glutathione-gated K+ efflux systems in Escherichia coti, and the proteins exhibit strong similarity at the level of both primary sequence and domain organization. The proteins are maintained closed by glutathione and are activated by binding of adducts formed between glutathione and electrophiles. By construction of equivalent mutations in each protein, this study has analyzed the control over inactive state of the proteins. A UV-induced mutation in KefB, L75S, causes rapid spontaneous K+ efflux but has only a minor effect on K+ efflux via KefC. Similarly amino acid substitutions that cause increased spontaneous activity in RefC have only small effects in RefB. Exchange of an eight amino acid region from KefC (HALESDIE) with the equivalent sequence from KefB (HELETAID) has identified a role for a group of acidic residues in controlling KefC activity. The mutations HELETALD and L74S in KefC act synergistically, and the activity of the resultant protein resembles that of KefB. We conclude that, despite the high degree of sequence similarity, KefB and KefC: exhibit different sensitivities to the same site-specific mutations.

AB - KefB and KefC are glutathione-gated K+ efflux systems in Escherichia coti, and the proteins exhibit strong similarity at the level of both primary sequence and domain organization. The proteins are maintained closed by glutathione and are activated by binding of adducts formed between glutathione and electrophiles. By construction of equivalent mutations in each protein, this study has analyzed the control over inactive state of the proteins. A UV-induced mutation in KefB, L75S, causes rapid spontaneous K+ efflux but has only a minor effect on K+ efflux via KefC. Similarly amino acid substitutions that cause increased spontaneous activity in RefC have only small effects in RefB. Exchange of an eight amino acid region from KefC (HALESDIE) with the equivalent sequence from KefB (HELETAID) has identified a role for a group of acidic residues in controlling KefC activity. The mutations HELETALD and L74S in KefC act synergistically, and the activity of the resultant protein resembles that of KefB. We conclude that, despite the high degree of sequence similarity, KefB and KefC: exhibit different sensitivities to the same site-specific mutations.

KW - ESCHERICHIA-COLI

KW - POTASSIUM CHANNELS

KW - ACTIVATION

KW - CLONING

KW - TRANSPORT

KW - GENE

M3 - Article

VL - 274

SP - 9524

EP - 9530

JO - The Journal of Biological Chemistry

JF - The Journal of Biological Chemistry

SN - 0021-9258

ER -