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Title: Preliminary structural studies of the transcriptional regulator CmeR from Campylobacter jejuni

Abstract

The transcriptional regulator CmeR from C. jejuni has been purified and crystallized and X-ray diffraction data have been collected to a resolution of 2.2 Å. In Campylobacter jejuni, a Gram-negative bacterial pathogen causing gastroenteritis in humans, the CmeR regulatory protein controls transcription of the multidrug transporter gene operon cmeABC. CmeR belongs to the TetR family of transcriptional regulators. The 210-residue CmeR consists of two functional motifs: an N-terminal DNA-binding domain and a C-terminal ligand-binding domain. It is predicted that the DNA-binding domain interacts directly with target promoters, while the C-terminal motif interacts with inducing ligands (such as bile salts). As an initial step towards confirming this structural model, recombinant CmeR protein containing a 6×His tag at the N-terminus was crystallized. Crystals of ligand-free CmeR belonged to space group P2{sub 1}2{sub 1}2, with unit-cell parameters a = 37.4, b = 57.6, c = 93.3 Å. Diffraction was observed to at least 2.2 Å at 100 K. Analysis of the detailed CmeR structure is currently in progress.

Authors:
 [1];  [2]; ;  [3];  [4];  [1];  [5];  [2];  [5]
  1. Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011 (United States)
  2. Department of Veterinary Microbiology, College of Veterinary Medicine, Iowa State University, Ames, IA 50011 (United States)
  3. Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States)
  4. Department of Anatomy, School of Medicine, University of California, San Francisco, CA 94143 (United States)
  5. (United States)
Publication Date:
OSTI Identifier:
22360250
Resource Type:
Journal Article
Resource Relation:
Journal Name: Acta Crystallographica. Section F; Journal Volume: 63; Journal Issue: Pt 1; Other Information: PMCID: PMC2330109; PMID: 17183170; PUBLISHER-ID: gj5010; OAI: oai:pubmedcentral.nih.gov:2330109; Copyright (c) International Union of Crystallography 2007; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United Kingdom
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRYSTALS; DNA; LIGANDS; PROTEINS; RESOLUTION; SALTS; SPACE GROUPS; STRUCTURAL MODELS; X-RAY DIFFRACTION

Citation Formats

Su, Chih-Chia, Shi, Feng, Gu, Ruoyu, Li, Ming, McDermott, Gerry, Yu, Edward W., E-mail: ewyu@iastate.edu, Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, Zhang, Qijing, and Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011. Preliminary structural studies of the transcriptional regulator CmeR from Campylobacter jejuni. United Kingdom: N. p., 2007. Web. doi:10.1107/S1744309106053127.
Su, Chih-Chia, Shi, Feng, Gu, Ruoyu, Li, Ming, McDermott, Gerry, Yu, Edward W., E-mail: ewyu@iastate.edu, Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, Zhang, Qijing, & Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011. Preliminary structural studies of the transcriptional regulator CmeR from Campylobacter jejuni. United Kingdom. doi:10.1107/S1744309106053127.
Su, Chih-Chia, Shi, Feng, Gu, Ruoyu, Li, Ming, McDermott, Gerry, Yu, Edward W., E-mail: ewyu@iastate.edu, Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, Zhang, Qijing, and Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011. Mon . "Preliminary structural studies of the transcriptional regulator CmeR from Campylobacter jejuni". United Kingdom. doi:10.1107/S1744309106053127.
@article{osti_22360250,
title = {Preliminary structural studies of the transcriptional regulator CmeR from Campylobacter jejuni},
author = {Su, Chih-Chia and Shi, Feng and Gu, Ruoyu and Li, Ming and McDermott, Gerry and Yu, Edward W., E-mail: ewyu@iastate.edu and Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 and Zhang, Qijing and Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011},
abstractNote = {The transcriptional regulator CmeR from C. jejuni has been purified and crystallized and X-ray diffraction data have been collected to a resolution of 2.2 Å. In Campylobacter jejuni, a Gram-negative bacterial pathogen causing gastroenteritis in humans, the CmeR regulatory protein controls transcription of the multidrug transporter gene operon cmeABC. CmeR belongs to the TetR family of transcriptional regulators. The 210-residue CmeR consists of two functional motifs: an N-terminal DNA-binding domain and a C-terminal ligand-binding domain. It is predicted that the DNA-binding domain interacts directly with target promoters, while the C-terminal motif interacts with inducing ligands (such as bile salts). As an initial step towards confirming this structural model, recombinant CmeR protein containing a 6×His tag at the N-terminus was crystallized. Crystals of ligand-free CmeR belonged to space group P2{sub 1}2{sub 1}2, with unit-cell parameters a = 37.4, b = 57.6, c = 93.3 Å. Diffraction was observed to at least 2.2 Å at 100 K. Analysis of the detailed CmeR structure is currently in progress.},
doi = {10.1107/S1744309106053127},
journal = {Acta Crystallographica. Section F},
number = Pt 1,
volume = 63,
place = {United Kingdom},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • The CmeABC multidrug efflux pump, which belongs to the resistance-nodulation-division (RND) family, recognizes and extrudes a broad range of antimicrobial agents and is essential for Campylobacter jejuni colonization of the animal intestinal tract by mediating the efflux of bile acids. The expression of CmeABC is controlled by the transcriptional regulator CmeR, whose open reading frame is located immediately upstream of the cmeABC operon. To understand the structural basis of CmeR regulation, we have determined the crystal structure of CmeR to 2.2 {angstrom} resolution, revealing a dimeric two-domain molecule with an entirely helical architecture similar to members of the TetR familymore » of transcriptional regulators. Unlike the rest of the TetR regulators, CmeR has a large center-to-center distance (54 {angstrom}) between two N termini of the dimer, and a large flexible ligand-binding pocket in the C-terminal domain. Each monomer forms a 20 {angstrom} long tunnel-like cavity in the ligand-binding domain of CmeR and is occupied by a fortuitous ligand that is identified as glycerol. The binding of glycerol to CmeR induces a conformational state that is incompatible with target DNA. As glycerol has a chemical structure similar to that of potential ligands of CmeR, the structure obtained mimics the induced form of CmeR. These findings reveal novel structural features of a TetR family regulator, and provide new insight into the mechanisms of ligand binding and CmeR regulation.« less
  • Survival E (SurE) protein from Campylobacter jejuni, a Gram-negative mesophile, has been overexpressed in Escherichia coli as a soluble protein, successfully purified and crystallized in two distinct crystal forms. Survival E (SurE) protein from Campylobacter jejuni, a Gram-negative mesophile, has been overexpressed in Escherichia coli as a soluble protein, successfully purified and crystallized in two distinct crystal forms. The first form belongs to space group P2{sub 1}2{sub 1}2{sub 1}, with a tetramer in the asymmetric unit and unit-cell parameters a = 80.5, b = 119.0, c = 135.3 Å. The second form belongs to space group C2, with unit-cell parametersmore » a = 121.4, b = 47.1, c = 97.8 Å, and contains a dimer in the asymmetric unit. Diffraction data have been collected from these crystal forms to 2.5 and 2.95 Å resolution, respectively.« less
  • Campylobacter jejuni is unusual among bacteria in possessing a eukaryotic-like system for N-linked protein glycosylation at Asn residues in sequons of the type Asp/Glu-Xaa-Asn-Xaa-Ser/Thr. However, little is known about the structural context of the glycosylated sequons, limiting the design of novel recombinant glycoproteins. To obtain more information on sequon structure, we have determined the crystal structure of the PEB3 (Cj0289c) dimer. PEB3 has the class II periplasmic-binding protein fold, with each monomer having two domains with a ligand-binding site containing citrate located between them, and overall resembles molybdate- and sulfate-binding proteins. The sequon around Asn90 is located within a surface-exposedmore » loop joining two structural elements. The three key residues are well exposed on the surface; hence, they may be accessible to the PglB oligosaccharyltransferase in the folded state.« less
  • Flagella of the bacteria Helicobacter pylori and Campylobacter jejuni are important virulence determinants, whose proper assembly and function are dependent upon glycosylation at multiple positions by sialic acid-like sugars, such as 5,7-diacetamido-3,5,7,9-tetradeoxy-l-glycero-l-manno-nonulosonic acid (pseudaminic acid (Pse)). The fourth enzymatic step in the pseudaminic acid pathway, the hydrolysis of UDP-2,4-diacetamido-2,4,6-trideoxy-{beta}-l-altropyranose to generate 2,4-diacetamido-2,4,6-trideoxy-l-altropyranose, is performed by the nucleotide sugar hydrolase PseG. To better understand the molecular basis of the PseG catalytic reaction, we have determined the crystal structures of C. jejuni PseG in apo-form and as a complex with its UDP product at 1.8 and 1.85 {angstrom} resolution, respectively. In addition,more » molecular modeling was utilized to provide insight into the structure of the PseG-substrate complex. This modeling identifies a His{sup 17}-coordinated water molecule as the putative nucleophile and suggests the UDP-sugar substrate adopts a twist-boat conformation upon binding to PseG, enhancing the exposure of the anomeric bond cleaved and favoring inversion at C-1. Furthermore, based on these structures a series of amino acid substitution derivatives were constructed, altering residues within the active site, and each was kinetically characterized to examine its contribution to PseG catalysis. In conjunction with structural comparisons, the almost complete inactivation of the PseG H17F and H17L derivatives suggests that His{sup 17} functions as an active site base, thereby activating the nucleophilic water molecule for attack of the anomeric C-O bond of the UDP-sugar. As the PseG structure reveals similarity to those of glycosyltransferase family-28 members, in particular that of Escherichia coli MurG, these findings may also be of relevance for the mechanistic understanding of this important enzyme family.« less
  • Within recent years it has become apparent that protein glycosylation is not limited to eukaryotes. Indeed, in Campylobacter jejuni, a Gram-negative bacterium, more than 60 of its proteins are known to be glycosylated. One of the sugars found in such glycosylated proteins is 2,4-diacetamido-2,4,6-trideoxy-α-d-glucopyranose, hereafter referred to as QuiNAc4NAc. The pathway for its biosynthesis, initiating with UDP-GlcNAc, requires three enzymes referred to as PglF, PglE, and PlgD. The focus of this investigation is on PglF, an NAD+-dependent sugar 4,6-dehydratase known to belong to the short chain dehydrogenase/reductase (SDR) superfamily. Specifically, PglF catalyzes the first step in the pathway, namely, themore » dehydration of UDP-GlcNAc to UDP-2-acetamido-2,6-dideoxy-α-d-xylo-hexos-4-ulose. Most members of the SDR superfamily contain a characteristic signature sequence of YXXXK where the conserved tyrosine functions as a catalytic acid or a base. Strikingly, in PglF, this residue is a methionine. Here we describe a detailed structural and functional investigation of PglF from C. jejuni. For this investigation five X-ray structures were determined to resolutions of 2.0 Å or better. In addition, kinetic analyses of the wild-type and site-directed variants were performed. On the basis of the data reported herein, a new catalytic mechanism for a SDR superfamily member is proposed that does not require the typically conserved tyrosine residue.« less