scholarly journals Further Characterization of Vibrio vulnificus Rugose Variants and Identification of a Capsular and Rugose Exopolysaccharide Gene Cluster

2008 ◽  
Vol 76 (4) ◽  
pp. 1485-1497 ◽  
Author(s):  
Brenda L. Grau ◽  
Margaret C. Henk ◽  
Katherine L. Garrison ◽  
Brett J. Olivier ◽  
Randall M. Schulz ◽  
...  
Keyword(s):  
Mouse Model ◽  
Gene Cluster ◽  
Capsular Polysaccharide ◽  
Vibrio Vulnificus ◽  
Three Dimensional ◽  
Extracellular Polysaccharide ◽  
Colony Morphology ◽  
Colony Type ◽  
Major Virulence Factor

ABSTRACT Capsular polysaccharide (CPS) is a major virulence factor in Vibrio vulnificus, and encapsulated strains have an opaque, smooth (OpS) colony morphology, while nonencapsulated strains have a translucent, smooth (TrS) colony morphology. Previously, we showed that OpS and TrS parental strains can yield a third colony type, rugose (R), and that the resulting strains, with the OpR and TrR phenotypes, respectively, form copious biofilms. Here we show that while OpR and TrR strains both produce three-dimensional biofilm structures that are indicative of rugose extracellular polysaccharide (rEPS) production, OpR strains also retain expression of CPS and are virulent in an iron-supplemented mouse model, while TrR strains lack CPS and are avirulent. Chlorine resistance assays further distinguished OpR and TrR isolates as exposure to 3 μg/ml NaOCl eradicated both OpS and OpR strains, while both TrS and TrR strains survived, but at rates which were significantly different from one another. Taken together, these results further emphasize the importance of CPS for virulence of V. vulnificus and establish a correlation between CPS expression and chlorine sensitivity in this organism. Using reverse transcriptase PCR, we also identified a nine-gene cluster associated with both CPS and rEPS expression in V. vulnificus, designated the wcr (capsular and rugose polysaccharide) locus, with expression occurring primarily in R variants. The latter results set the stage for characterization of functional determinants which individually or collectively contribute to expression of multiple EPS forms in this pathogen.

scholarly journals Molecular Characterization of Streptococcus pneumoniae Type 4, 6B, 8, and 18C Capsular Polysaccharide Gene Clusters

2001 ◽  
Vol 69 (3) ◽  
pp. 1244-1255 ◽  
Author(s):  
Sheng-Mei Jiang ◽  
Lei Wang ◽  
Peter R. Reeves
Keyword(s):  
Streptococcus Pneumoniae ◽  
Amino Acid ◽  
Gene Cluster ◽  
Capsular Polysaccharide ◽  
Gene Clusters ◽  
Amino Acid Sequences ◽  
Gene Encoding ◽  
Transmembrane Segments ◽  
Major Virulence Factor

ABSTRACT Capsular polysaccharide (CPS) is a major virulence factor inStreptococcus pneumoniae. CPS gene clusters of S. pneumoniae types 4, 6B, 8, and 18C were sequenced and compared with those of CPS types 1, 2, 14, 19F, 19A, 23F, and 33F. All have the same four genes at the 5′ end, encoding proteins thought to be involved in regulation and export. Sequences of these genes can be divided into two classes, and evidence of recombination between them was observed. Next is the gene encoding the transferase for the first step in the synthesis of CPS. The predicted amino acid sequences of these first sugar transferases have multiple transmembrane segments, a feature lacking in other transferases. Sugar pathway genes are located at the 3′ end of the gene cluster. Comparison of the four dTDP-l-rhamnose pathway genes (rml genes) of CPS types 1, 2, 6B, 18C, 19F, 19A, and 23F shows that they have the same gene order and are highly conserved. There is a gradient in the nature of the variation of rml genes, the average pairwise difference for those close to the central region being higher than that for those close to the end of the gene cluster and, again, recombination sites can be observed in these genes. This is similar to the situation we observed for rml genes of O-antigen gene clusters of Salmonella enterica. Our data indicate that the conserved first four genes at the 5′ ends and the relatively conservedrml genes at the 3′ ends of the CPS gene clusters were sites for recombination events involved in forming new forms of CPS. We have also identified wzx and wzy genes for all sequenced CPS gene clusters by use of motifs.

Elucidation of the K32 Capsular Polysaccharide Structure and Characterization of the KL32 Gene Cluster of Acinetobacter baumannii LUH5549

2020 ◽  
Vol 85 (2) ◽  
pp. 241-247 ◽  
Author(s):  
S. M. Cahill ◽  
N. P. Arbatsky ◽  
A. S. Shashkov ◽  
M. M. Shneider ◽  
A. V. Popova ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Gene Cluster ◽  
Capsular Polysaccharide

scholarly journals Characterization of the Type 8 Capsular Gene Cluster of Streptococcus pneumoniae

1999 ◽  
Vol 181 (19) ◽  
pp. 6214-6219 ◽  
Author(s):  
Rosario Muñoz ◽  
Marta Mollerach ◽  
Rubens López ◽  
Ernesto García
Keyword(s):  
Streptococcus Pneumoniae ◽  
Nucleotide Sequence ◽  
Gene Cluster ◽  
Complete Nucleotide Sequence ◽  
Capsular Polysaccharide ◽  
Open Reading Frames ◽  
Dna Fragment ◽  
Type 3 ◽  
Reading Frames

ABSTRACT The complete nucleotide sequence of the capsular gene cluster (cap8) responsible for the biosynthesis of the capsular polysaccharide of Streptococcus pneumoniae type 8 has been determined. The cap8 gene cluster, located between the genes dexB and aliA, is composed of 12 open reading frames. A 14.7-kb DNA fragment embracing the cap8genes was sufficient to transform an unencapsulated type 3 S. pneumoniae strain to a strain with the type 8 capsule. A possible scenario for the evolution of pneumococcal types 2 and 8 is outlined.

Colonial variation in Xanthomonas campestris NRRL B-1459 and characterization of the polysaccharide from a variant strain

1976 ◽  
Vol 22 (7) ◽  
pp. 942-948 ◽  
Author(s):  
M. C. Cadmus ◽  
S. P. Rogovin ◽  
K. A. Burton ◽  
J. E. Pittsley ◽  
C. A. Knutson ◽  
...  
Keyword(s):  
Xanthomonas Campestris ◽  
Extracellular Polysaccharide ◽  
Variant Form ◽  
Glucose Content ◽  
Colony Type ◽  
Molar Ratios ◽  
Large Colony ◽  
Predominant Variant ◽  
Small Colony

Stock cultures of Xanthomonas campestris NRRL B-1459 require special attention to maintenance and propagation to assure consistent production in good yields of the extracellular polysaccharide xanthan. Under customary conditions of propagative maintenance on agar slants, variant colony types develop that are smaller in size than the normal type. The rate of regression of the normal to the variant forms was diminished when the D-glucose content of the stock medium was sufficient to avoid depletion during storage and when transfer to fresh medium was reduced to 14-day intervals. Under conditions for polysaccharide production, the normal large-colony type gives crude culture liquors after 48 h of 7000 centipoise (cp) viscosity; the predominant variant form gives only 4000 cp. On the basis of 2.1% initial D-glucose, biopolymer yields for the normal and variant strains were 62 and 43%, respectively. Polysaccharide produced by the variant (small-colony type) differs adversely in solution properties from that of the parent strain (large-colony type); it differs also in its lower content of pyruvic acid and O-acetyl substituents. The molar ratios of constituent sugars (D-glucose, D-mannose, and D-glucuronic acid), however, were identical in polysaccharides with the normal and variant strains. Exclusion of colonial variants from fermentations is prerequisite to production of xanthan optimum in properties and yield.

scholarly journals Characterization of Colony Morphology Variants Isolated from Pseudomonas aeruginosa Biofilms

2005 ◽  
Vol 71 (8) ◽  
pp. 4809-4821 ◽  
Author(s):  
Mary Jo Kirisits ◽  
Lynne Prost ◽  
Melissa Starkey ◽  
Matthew R. Parsek
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Solid Medium ◽  
Three Dimensional ◽  
Solid Surfaces ◽  
Colony Morphology ◽  
Dimensional Structure ◽  
Wild Type ◽  
Wild Type Parent

ABSTRACT In this study, we report the isolation of small, rough, strongly cohesive colony morphology variants from aging Pseudomonas aeruginosa PAO1 biofilms. Similar to many of the P. aeruginosa colony morphology variants previously described in the literature, these variants autoaggregate in liquid culture and hyperadhere to solid surfaces. They also exhibit increased hydrophobicity and reduced motility compared to the wild-type parent strain. Despite the similarities in appearance of our colony morphology variant isolates on solid medium, the isolates showed a range of responses in various phenotypic assays. These variants form biofilms with significant three-dimensional structure and more biomass than the wild-type parent. To further explore the nature of the variants, their transcriptional profiles were evaluated. The variants generally showed increased expression of the psl and pel loci, which have been previously implicated in the adherence of P. aeruginosa to solid surfaces. When a mutation in the psl locus was introduced into a colony morphology variant, the colony morphology was only partially affected, but hyperadherence and autoaggregation were lost. Finally, similar colony morphology variants were found in isolates from cystic fibrosis patients. These variants displayed many of the same characteristics as the laboratory variants, suggesting a link between laboratory and cystic fibrosis biofilms.

scholarly journals Cyclic-di-GMP Regulates Extracellular Polysaccharide Production, Biofilm Formation, and Rugose Colony Development by Vibrio vulnificus

2008 ◽  
Vol 74 (13) ◽  
pp. 4199-4209 ◽  
Author(s):  
Alina Nakhamchik ◽  
Caroline Wilde ◽  
Dean A. Rowe-Magnus
Keyword(s):  
Biofilm Formation ◽  
Capsular Polysaccharide ◽  
Vibrio Vulnificus ◽  
Genomic Library ◽  
Extracellular Polysaccharide ◽  
Invasive Disease ◽  
Colony Development ◽  
Independent Manner ◽  
Disease Agent ◽  
And Control

ABSTRACT Vibrio vulnificus is a human and animal pathogen that carries the highest death rate of any food-borne disease agent. It colonizes shellfish and forms biofilms on the surfaces of plankton, algae, fish, and eels. Greater understanding of biofilm formation by the organism could provide insight into approaches to decrease its load in filter feeders and on biotic surfaces and control the occurrence of invasive disease. The capsular polysaccharide (CPS), although essential for virulence, is not required for biofilm formation under the conditions used here. In other bacteria, increased biofilm formation often correlates with increased exopolysaccharide (EPS) production. We exploited the translucent phenotype of acapsular mutants to screen a V. vulnificus genomic library and identify genes that imparted an opaque phenotype to both CPS biosynthesis and transport mutants. One of these encoded a diguanylate cyclase (DGC), an enzyme that synthesizes bis-(3′-5′)-cyclic-di-GMP (c-di-GMP). This prompted us to use this DGC, DcpA, to examine the effect of elevated c-di-GMP levels on several developmental pathways in V. vulnificus. Increased c-di-GMP levels induced the production of an EPS that was distinct from the CPS and dramatically enhanced biofilm formation and rugosity in a CPS-independent manner. However, the EPS could not compensate for the loss of CPS production that is required for virulence. In contrast to V. cholerae, motility and virulence appeared unaffected by elevated levels of c-di-GMP.

scholarly journals Characterization of the cassette containing genes for type 3 capsular polysaccharide biosynthesis in Streptococcus pneumoniae.

1995 ◽  
Vol 181 (3) ◽  
pp. 973-983 ◽  
Author(s):  
J P Dillard ◽  
M W Vandersea ◽  
J Yother
Keyword(s):  
Streptococcus Pneumoniae ◽  
Capsular Polysaccharide ◽  
Gene Cassette ◽  
Polysaccharide Biosynthesis ◽  
Hybridization Data ◽  
Major Virulence Factor ◽  
The Right ◽  
Type 3

The capsular polysaccharide is the major virulence factor of Streptococcus pneumoniae. Previously, we identified and cloned a region from the S. pneumoniae chromosome specific for the production of type 3 capsular polysaccharide. Now, by sequencing the region and characterizing mutations genetically and in an in vitro capsule synthesis assay, we have assigned putative functions to the products of the type-specific genes. Using DNA from the right end of the region in mapping studies, we have obtained further evidence indicating that the capsule genes of each serotype are contained in a gene cassette located adjacent to this region. We have cloned the region flanking the left end of the cassette from the type 3 chromosome and have found that it is repeated in the S. pneumoniae chromosome. The DNA sequence and hybridization data suggest a model for recombination of the capsule gene cassettes that not only describes the replacement of capsule genes, but also suggests an explanation for binary capsule type formation, and the creation of novel capsule types.

scholarly journals Evidence for an Intermediate Colony Morphology of Vibrio vulnificus

2006 ◽  
Vol 72 (6) ◽  
pp. 4356-4359 ◽  
Author(s):  
Thomas M. Rosche ◽  
Ben Smith ◽  
James D. Oliver
Keyword(s):  
High Frequency ◽  
Capsular Polysaccharide ◽  
Vibrio Vulnificus ◽  
Growth Conditions ◽  
Colony Morphology ◽  
Very High Frequency ◽  
Food Borne ◽  
A Site ◽  
Specific Deletion ◽  
Entire Gene

ABSTRACT Vibrio vulnificus causes both food-borne disease and wound infections. Most V. vulnificus strains express capsular polysaccharide (CPS), which is required for the virulence of this organism. Under standard growth conditions, CPS expression is lost at a relatively high frequency (10−3 to 10−4), resulting in a switch from an opaque (Op, CPS+) colony morphology to a translucent (Tr, CPS−) colony morphology. The wzb gene, which encodes a phosphatase required for CPS expression, has been proposed to be involved in this switch through a site-specific deletion of the entire gene. In an examination of five strains, we found that the frequency of wzb deletion in Tr colonies varies by strain and therefore does not account for all the Tr colonies that are seen. In addition, we have identified a third, intermediate (Int) colony morphotype, in which the colonies appear less opaque but are not fully translucent. PCR studies have demonstrated that Int colonies still contain the wzb gene, while reverse transcriptase PCR studies have shown that although Int strains retain expression of wzb, in some cases the transcription of wzb is reduced. Int strains switch to a true Tr (wzb negative) morphotype at a very high frequency (nearly 100%) under certain conditions. Finally, Int colonies, which in some cases can easily be mistaken for Tr colonies, have been observed to occasionally revert to Op, while Tr colonies containing a wzb deletion presumably are unable to revert to the encapsulated form.

Characterization of photosystem II with the atomic-force microscope

1992 ◽  
Vol 50 (2) ◽  
pp. 1146-1147
Author(s):  
Kathleen M. Marr ◽  
Mary K. Lyon
Keyword(s):  
Photosystem Ii ◽  
Atomic Force Microscope ◽  
Three Dimensional ◽  
Biologically Active ◽  
Atomic Force ◽  
Freeze Etching ◽  
Image Averaging ◽  
Oxygen Evolving ◽  
Averaging Techniques

Photosystem II (PSII) is different from all other reaction centers in that it splits water to evolve oxygen and hydrogen ions. This unique ability to evolve oxygen is partly due to three oxygen evolving polypeptides (OEPs) associated with the PSII complex. Freeze etching on grana derived insideout membranes revealed that the OEPs contribute to the observed tetrameric nature of the PSIl particle; when the OEPs are removed, a distinct dimer emerges. Thus, the surface of the PSII complex changes dramatically upon removal of these polypeptides. The atomic force microscope (AFM) is ideal for examining surface topography. The instrument provides a topographical view of individual PSII complexes, giving relatively high resolution three-dimensional information without image averaging techniques. In addition, the use of a fluid cell allows a biologically active sample to be maintained under fully hydrated and physiologically buffered conditions. The OEPs associated with PSII may be sequentially removed, thereby changing the surface of the complex by one polypeptide at a time.

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