Structures of the substrate-binding protein provide insights into the multiple compatible solute binding specificities of the <i>Bacillus subtilis</i> ABC transporter OpuC

Du, Yang; Shi, Weiwei; He, Yong‐Xing; Yang, Yong; Zhou, Cong‐Zhao; Chen, Yuxing

doi:10.1042/bj20102097

Cited by 45 publications

(94 citation statements)

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“…5A). The proteins most closely related to YehZ are A. fulgidus ProX (33) and B. subtilis OpuBC and OpuCC (34,35), which have identical four-tyrosine betainebinding boxes that form hydrophobic and cation-interactions with the trimethylammonium group of the ligand. Other osmoprotectant-binding proteins have tryptophans instead of tyrosines to form this aromatic box.…”

Section: Discussionmentioning

confidence: 99%

“…5A). We included sequences of class II PBPs that have been cocrystallized with betaine-related ligands in our analysis, including Archaeoglobus fulgidus ProX (PDB IDs 1SW1, 1SW2, 1SW4, and 1SW5) (33), B. subtilis OpuCC (PDB IDs 3PPO, 3PPQ, 3PPP, and 3PPR) (34) and OpuBC (PDB ID 3R6U) (35), Lactococcus lactis OpuAC (PDB ID 3L6H) (36), Sinorhizobium meliloti ChoX (PDB IDs 2REG and 2RIN) (37,38) and EhuB (PDB ID 2Q88) (39), E. coli ProX (PDB IDs 1R9L and 1R9Q) (40), and Borrelia burgdorferi ProX (PDB ID 3TMG). In addition, we compared YehZ-like proteins to B. abortus ChoX (Bab1_1593) and Bab2_0502, two PBPs previously tested for choline uptake (41).…”

Section: Figmentioning

confidence: 99%

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Conserved ABC Transport System Regulated by the General Stress Response Pathways of Alpha- and Gammaproteobacteria

et al. 2017

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Brucella abortus E1 is an EcfG family sigma factor that regulates the transcription of dozens of genes in response to diverse stress conditions and is required for maintenance of chronic infection in a mouse model. A putative ATPbinding cassette transporter operon, bab1_0223-bab1_0226, is among the most highly activated gene sets in the E1 regulon. The proteins encoded by the operon resemble quaternary ammonium-compatible solute importers but are most similar in sequence to the broadly conserved YehZYXW system, which remains largely uncharacterized. Transcription of yehZYXW is activated by the general stress sigma factor S in Enterobacteriaceae, which suggests a functional role for this transport system in bacterial stress response across the classes Alphaproteobacteria and Gammaproteobacteria. We present evidence that B. abortus YehZYXW does not function as an importer of known compatible solutes under physiological conditions and does not contribute to the virulence defect of a E1 -null strain. The sole in vitro phenotype associated with genetic disruption of this putative transport system is reduced growth in the presence of high Li ϩ ion concentrations. A crystal structure of B. abortus YehZ revealed a class II periplasmic binding protein fold with significant structural homology to Archaeoglobus fulgidus ProX, which binds glycine betaine. However, the structure of the YehZ ligand-binding pocket is incompatible with high-affinity binding to glycine betaine. This is consistent with weak measured binding of YehZ to glycine betaine and related compatible solutes. We conclude that YehZYXW is a conserved, stress-regulated transport system that is phylogenetically and functionally distinct from quaternary ammonium-compatible solute importers.IMPORTANCE Brucella abortus E1 regulates transcription in response to stressors encountered in its mammalian host and is necessary for maintenance of chronic infection in a mouse model. The functions of the majority of genes regulated by E1 remain undefined. We present a functional/structural analysis of a conserved putative membrane transport system (YehZYXW) whose expression is strongly activated by E1 . Though annotated as a quaternary ammonium osmolyte uptake system, experimental physiological studies and measured ligand-binding properties of the periplasmic binding protein (PBP), YehZ, are inconsistent with this function. A crystal structure of B. abortus YehZ provides molecular insight into differences between bona fide quaternary ammonium osmolyte importers and YehZ-related proteins, which form a distinct phylogenetic and functional group of PBPs.

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Section: Discussionmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

Conserved ABC Transport System Regulated by the General Stress Response Pathways of Alpha- and Gammaproteobacteria

et al. 2017

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“…In this small sample of proteins, OsmX is most closely related to YehZ, whose substrate specificity is not known, and to the A. fulgidus ProX protein, which has been shown to recognize glycine betaine and proline betaine with apparent K D values of ϳ50 nM (49). These three proteins fall into the same clade that also includes the B. subtilis OpuCC, which has broad specificity for osmoprotectants (19,32); the B. subtilis OpuBC protein, which is highly specific for choline (45); and the protein OpuCC of S. aureus, whose substrate specificity has not been determined. A different clade is formed by the glycine betaine/proline betaine binding fragment OpuAC from Lactococcus lactis (54), the glycine betaine/proline betaine/dimethylsulfonioacetate binding protein OpuAC of B. subtilis (50), the choline/acetylcholine binding protein ChoX of S. meliloti (42), and the ProX component of the ProU system of E. coli, which has high affinity for glycine betaine and proline betaine (K D values of 1 and 5 M, respectively) but does not bind proline.…”

Section: Figmentioning

confidence: 99%

Identification of a Third Osmoprotectant Transport System, the OsmU System, in Salmonella enterica

et al. 2012

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The growth of Salmonella enterica serovar Typhimurium mutants lacking the ProP and ProU osmoprotectant transport systems is stimulated by glycine betaine in high-osmolarity media, suggesting that this organism has an additional osmoprotectant transport system. Bioinformatic analysis revealed that the genome of this organism contains a hitherto-unidentified operon, designated osmU, consisting of four genes whose products show high similarity to ABC-type transport systems for osmoprotectants in other bacteria. The osmU operon was inactivated by a site-directed deletion, which abolished the ability of glycine betaine to alleviate the inhibitory effect of high osmolarity and eliminated the accumulation of [ 14 C]glycine betaine and [ 14 C]choline-O-sulfate in high-osmolarity media in a strain lacking the ProP and ProU systems. Although the OsmU system can take up glycine betaine and choline-O-sulfate, these two osmoprotectants are recognized at low affinity by this transporter, suggesting that there might be more efficient substrates that are yet to be discovered. The transcription of osmU is induced 23-fold by osmotic stress (0.3 M NaCl). The osmU operon is present in the genomes of a number of Enterobacteriaceae, and orthologs of the OsmU system can be recognized in a wide variety of Bacteria and Archaea. The structure of the periplasmic binding protein component of this transporter, OsmX, was modeled on the crystallographic structure of the glycine betaine-binding protein ProX of Archaeoglobus fulgidus; the resultant model indicated that the amino acids that constitute substrate-binding site, including an "aromatic cage" made up of four tyrosines, are conserved between these two proteins.

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“…AfProX, BsOpuBC and BsOpuCC have all been crystallized in complex with their natural substrates [33,53,54]. In each case the quaternary ammonium group sits in a cage whose sides are formed by four Tyr residues and whose base is the main chain of either an Asp or Asn.…”

Section: Binding Site Comparisonsmentioning

confidence: 99%

Crystal Structure of the Substrate-Binding Domain from Listeria monocytogenes Bile-Resistance Determinant BilE

2016

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BilE has been reported as a bile resistance determinant that plays an important role in colonization of the gastrointestinal tract by Listeria monocytogenes, the causative agent of listeriosis. The mechanism(s) by which BilE mediates bile resistance are unknown. BilE shares significant sequence similarity with ATP-binding cassette (ABC) importers that contribute to virulence and stress responses by importing quaternary ammonium compounds that act as compatible solutes. Assays using related compounds have failed to demonstrate transport mediated by BilE. The putative substrate-binding domain (SBD) of BilE was expressed in isolation and the crystal structure solved at 1.5 Å. Although the overall fold is characteristic of SBDs, the binding site varies considerably relative to the well-characterized homologs ProX from Archaeoglobus fulgidus and OpuBC and OpuCC from Bacillus subtilis. This suggests that BilE may bind an as-yet unknown ligand. Elucidation of the natural substrate of BilE could reveal a novel bile resistance mechanism.

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Structures of the substrate-binding protein provide insights into the multiple compatible solute binding specificities of the Bacillus subtilis ABC transporter OpuC

Cited by 45 publications

References 32 publications

Conserved ABC Transport System Regulated by the General Stress Response Pathways of Alpha- and Gammaproteobacteria

Conserved ABC Transport System Regulated by the General Stress Response Pathways of Alpha- and Gammaproteobacteria

Identification of a Third Osmoprotectant Transport System, the OsmU System, in Salmonella enterica

Crystal Structure of the Substrate-Binding Domain from Listeria monocytogenes Bile-Resistance Determinant BilE

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