Stop and go: regulation of chain length in the biosynthesis of bacterial polysaccharides

Whitfield, Chris; Larue, Kane

doi:10.1038/nsmb0208-121

Cited by 33 publications

(24 citation statements)

References 20 publications

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“…The protein encoded by the last gene in the cluster showed similarity to some chain length determinants (Wzz) from different bacteria and had a chain length determinant protein domain (Pfam accession number PF02706) between amino acids 16 and 155 characteristic of the Wzz family. This protein has a chain length determinant protein domain characteristic of the Wzz family between amino acids 16 and 155, two potential transmembrane domains (amino acid residues 41 to 63 and 332 to 354) in the N-and C-terminal regions, and a large hydrophilic central domain in the periplasmic face of the plasma membrane with different putative coiled-coil regions, like proteins that belong to the polysaccharide copolymerase superfamily (53). The similarity and topology suggested the possible role of this wzz gene in regulation of the A. hydrophila O34-antigen chain length.…”

Section: Resultsmentioning

confidence: 99%

The Aeromonas hydrophila wb * _O34 Gene Cluster: Genetics and Temperature Regulation

et al. 2008

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The Aeromonas hydrophila wb* O34 gene cluster of strain AH-3 (serotype O34) was cloned and sequenced. This cluster contains genes necessary for the production of O34-antigen lipopolysaccharide (LPS) in A. hydrophila. We determined, using either mutation or sequence homology, roles for the majority of genes in the cluster by using the chemical O34-antigen LPS structure obtained for strain AH-3. The O34-antigen LPS export system has been shown to be a Wzy-dependent pathway typical of heteropolysaccharide pathways. Furthermore, the production of A. hydrophila O34-antigen LPS in Escherichia coli K-12 strains is dependent on incorporation of the Gne enzyme (UDP-N-acetylgalactosamine 4-epimerase) necessary for the formation of UDP-galactosamine in these strains. By using rapid amplification of cDNA ends we were able to identify a transcription start site upstream of the terminal wzz gene, which showed differential transcription depending on the growth temperature of the strain. The Wzz protein is able to regulate the O34-antigen LPS chain length. The differential expression of this protein at different temperatures, which was substantially greater at 20°C than at 37°C, explains the previously observed differential production of O34-antigen LPS and its correlation with the virulence of A. hydrophila serotype O34 strains.In gram-negative bacteria lipopolysaccharide (LPS) is one of the major structural and immunodominant molecules of the outer membrane. LPS consists of three moieties: lipid A, core oligosaccharide, and O-specific antigen or O side chain. The O antigen is the external component of LPS, and it consists of a polymer of oligosaccharide repeating units. Another interesting feature is the high chemical variability shown by the O-antigen LPS, which leads to similar genetic variation in the genes involved in LPS biosynthesis, the so-called wb* cluster (for a review, see reference 45). The genetics of O-antigen biosynthesis have been intensively studied in the Enterobacteriaceae, and it has been shown that the wb* clusters usually contain genes involved in biosynthesis of activated sugars, glycosyl transferases, and O-antigen polymerases and in O-antigen export. Despite heterogeneity in the structures of the O antigens, only three pathways for assembly of O antigens have been recognized: the Wzy-dependent pathway, the ABC transporter-dependent pathway, and the synthase-dependent pathway (45).Mesophilic motile Aeromonas species are opportunistic and primary pathogens of a variety of aquatic and terrestrial animals, including humans; the clinical manifestations range from gastroenteritis to soft tissue infections, including septicemia and meningitis (5, 25). Mesophilic Aeromonas sp. serotype O34 strains have been recovered from moribund fish (33) and from clinical specimens (23); serotype O34 is the single most common Aeromonas serotype (24), accounting for 26.4% of all infections. Previous investigations have documented that serotype O34 strains are important causes of infections in humans (23,24). The varied clin...

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Section: Resultsmentioning

confidence: 99%

The Aeromonas hydrophila wb * _O34 Gene Cluster: Genetics and Temperature Regulation

et al. 2008

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“…For example, it has been proposed that the lengths of bacterial capsular polysaccharides are dictated by loss of affinity of a glycosyltransferase for a polymer beyond certain lengths (7), especially in ABC-transporter or synthase-dependent pathways (7,14). It is unclear how other proposed mechanisms for length control (7,14,33,(45)(46)(47) could lead to the product DPs generated. Polymerases that produce larger polysaccharides, such as HA, may also use tethering for length control.…”

Section: Glft2 Exhibits a Degree Of Length Control Similar To Other Cmentioning

confidence: 99%

A tethering mechanism for length control in a processive carbohydrate polymerization

May

Splain

Brotschi

et al. 2009

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

140

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Carbohydrate polymers are the most abundant organic substances on earth. Their degrees of polymerization range from tens to thousands of units, yet polymerases generate the relevant lengths without the aid of a template. To gain insight into template-independent length control, we investigated how the mycobacterial galactofuranosyltransferase GlfT2 mediates formation of the galactan, a polymer of galactofuranose residues that is an integral part of the cell wall. We show that isolated recombinant GlfT2 can catalyze the synthesis of polymers with degrees of polymerization that are commensurate with values observed in mycobacteria, indicating that length control by GlfT2 is intrinsic. Investigations using synthetic substrates reveal that GlfT2 is processive. The data indicate that GlfT2 controls length by using a substrate tether, which is distal from the site of elongation. The strength of interaction of that tether with the polymerase influences the length of the resultant polymer. Thus, our data identify a mechanism for length control by a template-independent polymerase.galactofuranose ͉ mycobacteria ͉ polymerase ͉ polysaccharide ͉ processivity

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“…We interpreted these bands as partial CA units covalently linked to lipid A-core OS. CA is synthesized and exported to the bacterial surface by a dedicated export system that involves several envelope proteins (55). We reasoned that in the absence of a functional WcaA protein, Und-P-P-linked incomplete CA units would not be exported and would instead compete with Und-P-P-linked O antigen for attachment to the lipid A-core OS.…”

Section: Figmentioning

confidence: 99%

Functional Characterization of UDP-Glucose:Undecaprenyl-Phosphate Glucose-1-Phosphate Transferases of Escherichia coli and Caulobacter crescentus

Patel

Nelson

Fernandez

et al. 2012

Journal of Bacteriology

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Stop and go: regulation of chain length in the biosynthesis of bacterial polysaccharides

Cited by 33 publications

References 20 publications

The Aeromonas hydrophila wb * _O34 Gene Cluster: Genetics and Temperature Regulation

The Aeromonas hydrophila wb * _O34 Gene Cluster: Genetics and Temperature Regulation

A tethering mechanism for length control in a processive carbohydrate polymerization

Functional Characterization of UDP-Glucose:Undecaprenyl-Phosphate Glucose-1-Phosphate Transferases of Escherichia coli and Caulobacter crescentus

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Stop and go: regulation of chain length in the biosynthesis of bacterial polysaccharides

Cited by 33 publications

References 20 publications

The Aeromonas hydrophila wb * O34 Gene Cluster: Genetics and Temperature Regulation

The Aeromonas hydrophila wb * O34 Gene Cluster: Genetics and Temperature Regulation

A tethering mechanism for length control in a processive carbohydrate polymerization

Functional Characterization of UDP-Glucose:Undecaprenyl-Phosphate Glucose-1-Phosphate Transferases of Escherichia coli and Caulobacter crescentus

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The Aeromonas hydrophila wb * _O34 Gene Cluster: Genetics and Temperature Regulation

The Aeromonas hydrophila wb * _O34 Gene Cluster: Genetics and Temperature Regulation