Molecular organization of the Escherichia coli gab cluster: nucleotide sequence of the structural genes gabD and gabP and expression of the GABA permease gene

Niegemann, Eckhard; Schulz, A.; Bartsch, Klaus

doi:10.1007/bf00245306

Cited by 61 publications

(58 citation statements)

References 35 publications

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“…However, as shown in Fig. 5 (b), we have identified significant sequence similarity, particularly in the unusual tryptophan-rich region, between CcmF proteins and the y-aminobutyric acid transporters of E. coli (Niegemann et al, 1993) and…”

Section: Isolation and Initial Characterization Of Mutant Hn48mentioning

confidence: 56%

Identification of the contiguous Paracoccus denitrificans ccmF and ccmH genes: disruption of ccmF, encoding a putative transporter, results in formation of an unstable apocytochrome c and deficiency in siderophore production

et al. 1998

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Apocytochrome ~5 5 0 was detected in the periplasm of a new mutant of Paracoccus denitrificans, HN48, that is pleiotropically lacking c-type cytochromes, produces reduced levels of siderophores and carries a T n 5 insertion in the ccmF gene for which sequence data, along with that for the contiguous ccmH, are reported. A counterpart to the ccmF gene was found in an archaebacterium but could not be located in the yeast genome, whereas mitochondria1 haem lyases in the latter were not present in an archaeobacterial or in eubacterial genomes. A topological analysis for CcmF is presented which indicates a t least eleven transmembrane helices, suggesting a role as a transporter; evidence against the substrate being haem is presented but sequence similarity with Escherichia coli y-aminobutyric acid transporter was identified. Analysis by pulse-chase methodology has shown that, in this and another cytochrome-c-def icient mutant, the apo form of P. denitrificans cytochrome css0 is much less stable than the holo form, directly demonstrating the presence of a periplasmic degradation system in P. denitrificans that removes non-functional proteins. A variety of phenotypes are observed for P. denitrificans mutated in different ccm genes, thus indicating that the stability of the ccm gene products does not require assembly of a complex of all the Ccm proteins.

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Section: Isolation and Initial Characterization Of Mutant Hn48mentioning

confidence: 56%

Identification of the contiguous Paracoccus denitrificans ccmF and ccmH genes: disruption of ccmF, encoding a putative transporter, results in formation of an unstable apocytochrome c and deficiency in siderophore production

et al. 1998

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“…The cma114 fusion contains mini-Tn5 lacZ-tet͞1 inserted in the gabT gene, encoding a glutamate:succinate semialdehyde aminotransferase. The gabT gene is located within the gabDTP operon, in which gabD encodes an NADPdependent succinate-semialdehyde dehydrogenase and gabP encodes a permease for ␥-aminobutyrate (37,38). This operon functions in the generation of succinate from ␥-aminobutyrate.…”

Section: Characterization Of the Extracellular Factor(s)mentioning

confidence: 99%

Escherichia coli genes regulated by cell-to-cell signaling

Baca-DeLancey

South

Ding

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

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Utilizing the bicistronic reporter transposon mini-Tn5 lacZ-tet͞1, we have identified lacZ fusions to four Escherichia coli genes͞operons that are strongly activated by the accumulation of self-produced extracellular signals. These fusions were designated cma9, cma48, cma113, and cma114 for conditioned medium activated. Each of the cma fusions was expressed in a growth phase-dependent manner, and the presence of conditioned medium from a stationary phase E. coli culture resulted in the premature activation of these fusions in cells at early to mid-logarithmic phase. The cma48 and cma114 fusions were dependent on RpoS for growth phase expression and response to extracellular factors. The extracellular factors that activated the cma9, cma48, and cma114 fusions were produced in both rich complex and defined minimal media. The cma fusions were shown to be within the cysK (cma9), astD (cma48), tnaB (cma113), and gabT (cma114) genes. These genes function in the uptake, synthesis, or degradation of amino acids that yield pyruvate and succinate.Bacteria are capable of regulating gene expression in response to a variety of extracellular signals. When the signal is produced by the bacterium itself, this type of regulation is termed autoinduction or quorum sensing (1-4). The composition of signaling molecules can include mixtures of amino acids, peptides, fatty acids, and acyl derivatives of homoserine lactone (1-4, 5-7). These signaling molecules can regulate gene expression by a number of mechanisms, including modulating the activity of members of the LuxR family, interacting with two-component systems, and inhibiting phosphatases (1,3,(8)(9)(10). The cellular processes regulated by quorum sensing are diverse, and some examples include spore formation, activation of luminescence, competence, conjugal transfer of plasmid DNA, regulation of virulence genes, regulation of peptidoglycan O-acetylation, and biofilm maturation (11)(12)(13)(14)(15)(16)(17)(18)(19)(20).In Escherichia coli, the regulation of gene expression by extracellular signals has also been established. Expression of the rpoS gene, encoding the alternate sigma factor S ( 38 ) involved in stationary-phase and osmoregulated gene expression is stimulated by the presence of a factor in conditioned medium (21,22). Studies by Huisman and Kolter (23) indicate that rpoS expression is decreased in a thrA, metL, lysC triple mutant that is defective in production of homoserine, and expression could be restored by exogenous homoserine lactone. However, the role of homoserine lactone or an acylated derivative in RpoS expression is unclear. Additional E. coli genes subject to regulation by extracellular factors include sdiA and the ftsQAZ cell division gene cluster (22,24). Recent studies by Surette and Bassler (25) have revealed that E. coli produces a signal that can substitute for AI-2, one of two Vibrio harveyi signals that control luminescence gene expression. The E. coli signal was heat labile, produced at mid-exponential phase of growth, and degraded at sta...

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“…The Escherichia coli γ-aminobutyric acid (GABA) transporter GabP (gab permease) is a prototype amine-polyamine-choline transporter (APC) superfamily transporter, which has been sequenced [1], expressed under lac control [2] and extensively characterized with respect to its ligand recognition properties [2][3][4][5]. Gram-negative [2][3][4]6] and Gram-positive [5,7] organisms express homologous gab permeases that function as the exclusive mediators of GABA transport across the plasma membrane.…”

Section: Introductionmentioning

confidence: 99%

“…The CAR is found in the helix 8 and loop 8-9 domain of a multitude of carriers from the APC superfamily [8] ; CAR-like structures have been noted in Abbreviations used : APC superfamily, amine-polyamine-choline transporter superfamily ; BM, benzophenone-4-maleimide ; CAR, consensus amphipathic region ; DTNB, 5,5h-dithiobis-(2-nitrobenzoic acid) ; DTT, dithiothreitol ; FM, fluorescein 5-maleimide ; GABA, γ-aminobutyric acid ; guvacine, 1,2,3,6-tetrahydro-3-pyridinecarboxylic acid ; IAA, iodoacetamide ; MMTS, methyl methanethiosulphonate ; MTSEA, 2-aminoethyl methanethiosulphonate ; MTSES, 2-sulphonatoethyl methanethiosulphonate ; MTSET, [2-(trimethylammonium)ethyl] methanethiosulphonate ; NEM, N-ethylmaleimide ; PCMB, p-hydroxymercuribenzoate ; PCMBS, p-chloromercuribenzenesulphonate ; SPS, ' sensitive polar surface ' ; TM, transmembrane segment. 1 To whom correspondence should be addressed (e-mail steven.king!utmb.edu).…”

Section: Introductionmentioning

confidence: 99%

Identification of the amine–polyamine–choline transporter superfamily ‘consensus amphipathic region’ as the target for inactivation of the Escherichia coli GABA transporter GabP by thiol modification reagents. Role of Cys-300 in restoring thiol sensitivity to GabP lacking Cys

King

1999

Biochemical Journal

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The Escherichia coli γ-aminobutyric acid transporter GabP (gab permease) contains a functionally significant cysteine residue (Cys-300) within its consensus amphipathic region (CAR), a putative channel-forming structure that extends out of transmembrane helix 8 and into the adjoining cytoplasmic loop 8-9 of transporters from the amine-polyamine-choline (APC) superfamily. Here we show that of the five cysteine residues (positions 158, 251, 291, 300 and 443) in the E. coli GabP, Cys-300 is the one that renders the transport activity sensitive to inhibition by thiol modification reagents: whereas substituting Ala for Cys-300 mimics the inhibitory effect of thiol modification, substituting Ala at position 158, 251, 291 or 443 preserves robust transport activity and confers no resistance to thiol inactivation; and whereas the robustly active Cys-300 single-Cys mutant is fully sensitive to thiol modification, other single-Cys mutants (Cys at 158, 251, 291 or 443) exhibit kinetically compromised transport activities that resist further chemical inactivation by thiol reagents. The present study reveals additionally that Cys-300 exhibits (1) sensitivity to hydrophobic thiol reagents, (2) general resistance to bulky (fluorescein 5-maleimide) and/or charged {2-sulphonatoethyl methanethiosulphonate or [2-(trimethylammonium)ethyl] methanethiosulphonate} thiol reagents and (3) a peculiar sensitivity to p-chloromercuribenzenesulphonate (PCMBS). The accessibility of PCMBS to Cys-300 (located midway through the lipid bilayer) might be related to the structural similarity that it shares with guvacine (1,2,3,6-tetrahydro-3-pyridinecarboxylic acid), a transported GabP substrate. These structural requirements for thiol sensitivity provide the first chemical evidence consistent with channel-like access to the polar surface of the CAR, a physical configuration that might provide a basis for understanding how this region impacts the function of APC transporters generally [Closs, Lyons, Kelly and Cunningham (1993) J. Biol. Chem. 268, 20796-20800] and the gab permease particularly [Hu and King (1998) Biochem. J. 300, 771-776].

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Molecular organization of the Escherichia coli gab cluster: nucleotide sequence of the structural genes gabD and gabP and expression of the GABA permease gene

Cited by 61 publications

References 35 publications

Identification of the contiguous Paracoccus denitrificans ccmF and ccmH genes: disruption of ccmF, encoding a putative transporter, results in formation of an unstable apocytochrome c and deficiency in siderophore production

Identification of the contiguous Paracoccus denitrificans ccmF and ccmH genes: disruption of ccmF, encoding a putative transporter, results in formation of an unstable apocytochrome c and deficiency in siderophore production

Escherichia coli genes regulated by cell-to-cell signaling

Identification of the amine–polyamine–choline transporter superfamily ‘consensus amphipathic region’ as the target for inactivation of the Escherichia coli GABA transporter GabP by thiol modification reagents. Role of Cys-300 in restoring thiol sensitivity to GabP lacking Cys

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