A transporter of Escherichia coli specific for l- and d-methionine is the prototype for a new family within the ABC superfamily

Zhang, Zhongge; Feige, Jérôme N.; Chang, Amy; Anderson, Iain; Brodianski, Vadim M.; Vitreschak, Alexei G.; Gelfand, Mikhail S.; Saier, Milton H.

doi:10.1007/s00203-003-0561-4

Cited by 57 publications

(56 citation statements)

References 35 publications

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“…That the genome of T. pallidum does not include either an ABC permease or an ATPase in proximity to the tp34 gene does not preclude, however, Tp34 from acting as a receptor for such a metal ion-transport system; the permease and ATPase may be encoded at distant genomic loci. In fact, in the case of the methionine transporter (Tp32) in T. pallidum, its hypothetical ATPase (tp0120) and permease (tp0119) are together but distant from tp32 (tp0821) (21,74). Whether such non-operonic ABC transport systems are yet another unusual feature of T. pallidum remains to be more fully explored via additional functional studies on other treponemal ABC transport systems in this organism.…”

Section: Resultsmentioning

confidence: 99%

Crystal Structure of the Tp34 (TP0971) Lipoprotein of Treponema pallidum

Deka

Brautigam

Tomson

et al. 2007

Journal of Biological Chemistry

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The Tp34 (TP0971) membrane lipoprotein of Treponema pallidum, an obligate human pathogen and the agent of syphilis, was previously reported to have lactoferrin binding properties. Given the non-cultivatable nature of T. pallidum, a structureto-function approach was pursued to clarify further potential relationships between the Tp34 structural and biochemical properties and its propensity to bind human lactoferrin. The crystal structure of a nonacylated, recombinant form of Tp34 (rTp34), solved to a resolution of 1.9 Å , revealed two metaloccupied binding sites within a dimer; the identity of the ion most likely was zinc. Residues from both of the monomers contributed to the interfacial metal-binding sites; a novel feature was that the ␦-sulfur of methionine coordinated the zinc ion. Analytical ultracentrifugation showed that, in solution, rTp34 formed a metal-stabilized dimer and that rTp34 bound human lactoferrin with a stoichiometry of 2:1. Isothermal titration calorimetry further revealed that rTp34 bound human lactoferrin at high (submicromolar) affinity. Finally, membrane topology studies revealed that native Tp34 is not located on the outer surface (outer membrane) of T. pallidum but, rather, is periplasmic. How propensity of Tp34 to bind zinc and the iron-sequestering lactoferrin may relate overall to the biology of T. pallidum infection in humans is discussed.

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Section: Resultsmentioning

confidence: 99%

Crystal Structure of the Tp34 (TP0971) Lipoprotein of Treponema pallidum

Deka

Brautigam

Tomson

et al. 2007

Journal of Biological Chemistry

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“…1,2 An ATP Binding Cassette (ABC) transporter, [3][4][5] MetNI consists of two copies of the conserved ABC subunit MetN that is the hallmark of this transporter superfamily, in complex with two copies of the transmembrane domain (TMD) subunit MetI. [6][7][8] Each MetN ABC subunit can be further divided into two subdomains 9 ; the nucleotide binding domain (NBD; residues 1-245) and a C-terminal domain (C2; residues 265-343) connected by a linker spanning residues 246-264. The MetI subunits contain five transmembrane (TM) helices that define a conserved core present in the Type I family of ABC importers, 10,11 including the previously solved structures of the ModBC molybdate 12 and MalFGK 2 maltose 13 transporters.…”

Section: Introductionmentioning

confidence: 99%

Inward facing conformations of the MetNI methionine ABC transporter: Implications for the mechanism of transinhibition

et al. 2011

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Two new crystal structures of the Escherichia coli high affinity methionine uptake ATP Binding Cassette (ABC) transporter MetNI, purified in the detergents cyclohexyl-pentyl-b-Dmaltoside (CY5) and n-decyl-b-D-maltopyranoside (DM), have been solved in inward facing conformations to resolutions of 2.9 and 4.0 Å , respectively. Compared to the previously reported 3.7 Å resolution structure of MetNI purified in n-dodecyl-b-D-maltopyranoside (DDM), the higher resolution of the CY5 data enabled significant improvements to the structural model in several regions, including corrections to the sequence registry, and identification of ADP in the nucleotide binding site. CY5 crystals soaked with selenomethionine established details of the methionine binding site in the C2 regulatory domain of the ABC subunit, including the displacement of the side chain of MetN residue methionine 301 by the exogenous ligand. When compared to the CY5 or DDM structures, the DM structure exhibits a significant repositioning of the dimeric C2 domains, including an unexpected register shift in the intermolecular b-sheet hydrogen bonding between monomers, and a narrowing of the nucleotide binding space. The immediate proximity of the exogenous methionine binding site to the conformationally variable dimeric interface provides an indication of how methionine binding to the regulatory domains might mediate the phenomenon of transinhibition.

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“…1). Two methionine transport systems in microorganisms have been described previously: an ABC transporter that belongs to the methionine uptake transporter (MUT) family (23,33,48) and BcaP of the permease transporter family (8). Methionine can be produced directly by the methylation of homocysteine by a methionine synthase (MetE) in conjunction with a methylenetetrahydrofolate reductase (MetF) (see Fig.…”

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Control of Methionine Synthesis and Uptake by MetR and Homocysteine in Streptococcus mutans

et al. 2007

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thermophilus. These data suggest a common mechanism for the regulation of the methionine supply in streptococci. However, some streptococcal species are unable to synthesize the homocysteine coeffector. This intriguing feature is discussed in the light of comparative genomics and streptococcal ecology.The sulfur-containing amino acid methionine is of major importance in the cellular metabolism of all living organisms. Methionine is the universal initiator of protein synthesis, and its derivative S-adenosylmethionine (SAM) and autoinducer-2 (AI-2) (see Fig. 1) are involved in a variety of cellular processes. SAM serves as the major biological methyl donor in methylation reactions, which are essential for the biosynthesis of phospholipids, proteins, DNA, and RNA (11), and the signaling molecule AI-2 is involved in interspecies communication and gene regulation in both gram-negative and grampositive bacteria (7,21,46). Methionine availability is limiting for the growth of several lactic acid bacteria (4) and group B streptococci (39), and methionine biosynthetic genes are essential for the virulence of Brucella melitensis (28), Haemophilus parasuis (22), and Salmonella enterica (9).Methionine can be either supplied from the environment by the cell or synthesized de novo (see Fig. 1). Two methionine transport systems in microorganisms have been described previously: an ABC transporter that belongs to the methionine uptake transporter (MUT) family (23,33,48) and BcaP of the permease transporter family (8). Methionine can be produced directly by the methylation of homocysteine by a methionine synthase (MetE) in conjunction with a methylenetetrahydrofolate reductase (MetF) (see Fig. 1) (16,27). Homocysteine can be synthesized from (i) cysteine by the transsulfuration pathway (MetA, MetB, and MetC), (ii) sulfide by the sulfhydrylation pathway (MetA and CysD), and (iii) methionine by the SAM recycling pathway (MetK, Pfs, and LuxS). Both the transsulfuration and sulfhydrylation pathways start with O-acylhomoserine, synthesized by the acylation of homoserine by homoserine acyltransferase (MetA). In the transsulfuration pathway, homocysteine is formed from O-acylhomoserine and cysteine in two steps, with the intermediary formation of cystathionine. This process requires the sequential action of a cystathionine ␥-synthase (MetB) and a cystathionine ␤-lyase (MetC). In the sulfhydrylation pathway, homocysteine is directly synthesized from O-acylhomoserine and sulfide by Oacylhomoserine sulfhydrylase (CysD). Finally, in the SAM recycling pathway, methionine serves as a substrate for the synthesis of homocysteine, after its activation by ATP to form SAM. The utilization of SAM as a methyl donor results in the formation of S-adenosylhomocysteine, which is degraded into AI-2 and homocysteine by the successive action of an S-adenosylhomocysteine nucleosidase (Pfs) and an S-ribosylhomocysteinase (LuxS) (see Fig. 1).While methionine biosynthetic enzymes and metabolic pathways are well conserved among bacteria, the regulation of methi...

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A transporter of Escherichia coli specific for l- and d-methionine is the prototype for a new family within the ABC superfamily

Cited by 57 publications

References 35 publications

Crystal Structure of the Tp34 (TP0971) Lipoprotein of Treponema pallidum

Crystal Structure of the Tp34 (TP0971) Lipoprotein of Treponema pallidum

Inward facing conformations of the MetNI methionine ABC transporter: Implications for the mechanism of transinhibition

Control of Methionine Synthesis and Uptake by MetR and Homocysteine in Streptococcus mutans

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