Functional exchangeability of the ABC proteins of the periplasmic binding protein-dependent transport systems Ugp and Mal of Escherichia coli

Hekstra, Doeke R.; Tommassen, Jan

doi:10.1128/jb.175.20.6546-6552.1993

Cited by 57 publications

(63 citation statements)

References 47 publications

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“…This observation indicated that HisP and MalK share domains that are exchangeable, whereas other domains confer system specificity by providing for interactions between the membrane-spanning protein and the ATP-binding protein (12,17). Furthermore, complete ATP-binding proteins have successfully been exchanged between the Mal and Ugp transporters, which in E. coli transport maltose and sn-glycerol-3-phosphate, respectively (5). The N-terminal parts of the UgpC and MalK proteins exhibit approximately 60% sequence identity, which is much higher than the 35.6% sequence identity over the first 150 amino acids between the TauB and SsuB proteins.…”

Section: Discussionmentioning

confidence: 88%

Deletion Analysis of the Escherichia coli Taurine and Alkanesulfonate Transport Systems

2000

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The Escherichia coli tauABCD and ssuEADCB gene clusters are required for the utilization of taurine and alkanesulfonates as sulfur sources and are expressed only under conditions of sulfate or cysteine starvation. tauD and ssuD encode an ␣-ketoglutarate-dependent taurine dioxygenase and a reduced flavin mononucleotidedependent alkanesulfonate monooxygenase, respectively. These enzymes are responsible for the desulfonation of taurine and alkanesulfonates. The amino acid sequences of SsuABC and TauABC exhibit similarity to those of components of the ATP-binding cassette transporter superfamily, suggesting that two uptake systems for alkanesulfonates are present in E. coli. Chromosomally located in-frame deletions of the tauABC and ssuABC genes were constructed in E. coli strain EC1250, and the growth properties of the mutants were studied to investigate the requirement for the TauABC and SsuABC proteins for growth on alkanesulfonates as sulfur sources. Complementation analysis of in-frame deletion mutants confirmed that the growth phenotypes obtained were the result of the in-frame deletions constructed. The range of substrates transported by these two uptake systems was largely reflected in the substrate specificities of the TauD and SsuD desulfonation systems. However, certain known substrates of TauD were transported exclusively by the SsuABC system. Mutants in which only formation of hybrid transporters was possible were unable to grow with sulfonates, indicating that the individual components of the two transport systems were not functionally exchangeable. The TauABCD and SsuEADCB systems involved in alkanesulfonate uptake and desulfonation thus are complementary to each other at the levels of both transport and desulfonation.In Escherichia coli, sulfate starvation causes increased synthesis of several proteins involved in scavenging sulfur from alternative sulfur sources (15). Recently, two sets of genes whose expression is derepressed in the absence of sulfate or cysteine were identified. The tauABCD gene cluster, located at 8.5 min on the E. coli chromosome, encodes a sulfonate-sulfur utilization system that is specifically involved in the utilization of taurine (2-aminoethanesulfonic acid) as a source of sulfur. Disruption of tauB, tauC, or tauD resulted in the loss of the ability to utilize taurine as a source of sulfur but did not affect the utilization of a range of other aliphatic sulfonates (21). The TauD protein is an ␣-ketoglutarate-dependent taurine dioxygenase (3), and the TauABC proteins exhibit similarity to ATP-binding cassette (ABC)-type transport systems (21). A second set of genes, the ssuEADCB gene cluster, located at 21.4 min on the chromosome, enables E. coli to utilize aliphatic sulfonates other than taurine as a source of sulfur. Deletion of ssuEADCB caused an inability to utilize alkanesulfonates but did not affect the utilization of taurine (24). SsuD is a monooxygenase that catalyzes the desulfonation of a wide range of sulfonated substrates other than taurine, including C 2 to C 10...

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Section: Discussionmentioning

confidence: 88%

Deletion Analysis of the Escherichia coli Taurine and Alkanesulfonate Transport Systems

2000

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“…UgpB is a specific binding protein, and ugpA and ugpE are membrane-imbedded proteins. UgpC is an ATP-binding protein that has a strong homology with the functionally exchangeable protein (MalK) for maltose transport (21). UgpQ is a glycerol phosphoryl phosphodiesterase that only hydrolyzes the assimilated diesters at the inner surface of the cytoplasmic membrane, and thus is not required for glycerol phosphate transport (20).…”

Section: Resultsmentioning

confidence: 99%

Subcellular localization of marine bacterial alkaline phosphatases

Luo¹,

Benner

Long

et al. 2009

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

238

223

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Bacterial alkaline phosphatases (APases) are important enzymes in organophosphate utilization in the ocean. The subcellular localization of APases has significant ecological implications for marine biota but is largely unknown. The extensive metagenomic sequence databases from the Global Ocean Sampling Expedition provide an opportunity to address this question. A bioinformatics pipeline was developed to identify marine bacterial APases from the metagenomic databases, and a consensus classification algorithm was designed to predict their subcellular localizations. We identified 3,733 bacterial APase sequences (including PhoA, PhoD, and PhoX) and found that cytoplasmic (41%) and extracellular (30%) APases exceed their periplasmic (17%), outer membrane (12%), and inner membrane (0.9%) counterparts. The unexpectedly high abundance of cytoplasmic APases suggests that the transport and intracellular hydrolysis of small organophosphate molecules is an important mechanism for bacterial acquisition of phosphorus (P) in the surface ocean. On average, each marine bacterium possessed at least one suite of uptake of glycerol phosphate (ugp) genes (e.g., ugpA, ugpB, ugpC, ugpE) for dissolved organic phosphorus (DOP) transport, but only half of them had ugpQ, which hydrolyzes transported DOP, indicating that cytoplasmic APases play a role in hydrolyzing transported DOP. The most abundant heterotrophic marine bacteria, ␣-and ␥-Proteobacteria, might hydrolyze DOP outside the cytoplasmic membrane, but the former could also transport and hydrolyze DOP in the cytoplasm. The abundant extracellular APases could provide bioavailable P for organisms that cannot directly access organophosphates, and thereby increase marine biological productivity and diversity.PhoD ͉ PhoX ͉ PhoA ͉ uptake of glycerol phosphate ͉ protein localization

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“…In addition to mutants with point mutations in fhuB, which are albomycin resistant and fail to transport ferrichrome (25), derivatives that are impaired in the uptake of the different iron (III) hydroxamates to various extents were isolated. It is unlikely that FhuC recognizes ferric hydroxamates, since it has been demonstrated that the FhuC equivalent MalK of maltose transport complements a UgpC mutant of sn-glycerol-3-phosphate transport and vice versa (18), excluding substrate specificity of these energy-providing proteins. In this paper, it is shown that FhuD to a large extent contributes to the substrate specificity of transport through the cytoplasmic membrane.…”

Section: Discussionmentioning

confidence: 99%

Ferrichrome transport in Escherichia coli K-12: altered substrate specificity of mutated periplasmic FhuD and interaction of FhuD with the integral membrane protein FhuB

1995

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FhuD is the periplasmic binding protein of the ferric hydroxamate transport system of Escherichia coli. FhuD was isolated and purified as a His-tag-labeled derivative on a Ni-chelate resin. The dissociation constants for ferric hydroxamates were estimated from the concentration-dependent decrease in the intrinsic fluorescence intensity of His-tag-FhuD and were found to be 0.4 M for ferric aerobactin, 1.0 M for ferrichrome, 0.3 M for ferric coprogen, and 5.4 M for the antibiotic albomycin. Ferrichrome A, ferrioxamine B, and ferrioxamine E, which are poorly taken up via the Fhu system, displayed dissociation constants of 79, 36, and 42 M, respectively. These are the first estimated dissociation constants reported for a binding protein of a microbial iron transport system. Mutants impaired in the interaction of ferric hydroxamates with FhuD were isolated. One mutated FhuD, with a W-to-L mutation at position 68 [FhuD(W68L)], differed from wild-type FhuD in transport activity in that ferric coprogen supported promotion of growth of the mutant on iron-limited medium, while ferrichrome was nearly inactive. The dissociation constants of ferric hydroxamates were higher for FhuD(W68L) than for wild-type FhuD and lower for ferric coprogen (2.2 M) than for ferrichrome (156 M). Another mutated FhuD, FhuD(A150S, P175L), showed a weak response to ferrichrome and albomycin and exhibited dissociation constants two-to threefold higher than that of wild-type FhuD. Interaction of FhuD with the cytoplasmic membrane transport protein FhuB was studied by determining protection of FhuB degradation by trypsin and proteinase K and by cross-linking experiments. His-tag-FhuD and His-tag-FhuD loaded with aerobactin specifically prevented degradation of FhuB and were cross-linked to FhuB. FhuD loaded with substrate and also FhuD free of substrate were able to interact with FhuB.Transport of ferric hydroxamates into Escherichia coli requires outer membrane receptor proteins for certain ferric hydroxamates (6) and a periplasmic binding-protein-dependent system of transport across the cytoplasmic membrane that is common for all ferric hydroxamates (6, 24). The latter consists of the FhuD protein in the periplasm, the integral transport protein FhuB in the cytoplasmic membrane, and the FhuC protein, which is associated with the cytoplasmic membrane (7,8,26,27,29,42) and presumably energizes transport into the cytoplasm by ATP hydrolysis. Binding of substrates to the FhuD protein has been demonstrated by proteolysis experiments; only ferric hydroxamates that were transported, aerobactin, ferrichrome, and coprogen, prevented degradation of FhuD, while ferric hydroxamates that were not transported by the Fhu system of E. coli did not protect FhuD from being hydrolyzed (28). No data for the activity of periplasmic proteins for ferric siderophore transport systems other than those for FhuD exist. Studies of the interactions of ferric siderophores with their cognate periplasmic proteins are hampered by the very low concentrations of the binding protei...

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Functional exchangeability of the ABC proteins of the periplasmic binding protein-dependent transport systems Ugp and Mal of Escherichia coli

Cited by 57 publications

References 47 publications

Deletion Analysis of the Escherichia coli Taurine and Alkanesulfonate Transport Systems

Deletion Analysis of the Escherichia coli Taurine and Alkanesulfonate Transport Systems

Subcellular localization of marine bacterial alkaline phosphatases

Ferrichrome transport in Escherichia coli K-12: altered substrate specificity of mutated periplasmic FhuD and interaction of FhuD with the integral membrane protein FhuB

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