Fitnat Yildiz

Characterization of the Vibrio cholerae extracellular matrix: a top-down solid-state NMR approach.

Published in Biochimica et Biophysica Acta

Bacterial biofilms are communities of bacterial cells surrounded by a self-secreted extracellular matrix. Biofilm formation by Vibrio cholerae, the human pathogen responsible for cholera, contributes to its environmental survival and infectivity. Important genetic and molecular requirements have been identified for V. cholerae biofilm formation, ye...

An image-based 384-well high-throughput screening method for the discovery of biofilm inhibitors in Vibrio cholerae.

Published in Molecular BioSystems

Bacterial biofilms are assemblages of bacterial cells and extracellular matrix that result in the creation of surface-associated macrocolony formation. Most bacteria are capable of forming biofilms under suitable conditions. Biofilm formation by pathogenic bacteria on medical implant devices has been linked to implant rejection in up to 10% of case...

Attenuated effect of oxygen on photopigment synthesis in Rhodospirillum centenum.

Published in Journal of Bacteriology

Rhodospirillum centenum resembles typical nonsulfur photosynthetic bacteria in a number of respects, including its ability to grow either anaerobically as a phototroph or aerobically as a heterotroph. We demonstrate, however, that R. centenum is unusual in its ability to synthesize a functional photosynthetic apparatus regardless of the presence of...

Response of Vibrio cholerae to Low-Temperature Shifts: CspV Regulation of Type VI Secretion, Biofilm Formation, and Asso...

Published in Applied and Environmental Microbiology

You ve come a long way: c-di-GMP signaling.

Published in Current Opinion in Microbiology

Cyclic dimeric guanosine monophosphate (c-di-GMP) is a common, bacterial second messenger that regulates diverse cellular processes in bacteria. Opposing activities of diguanylate cyclases (DGCs) and phosphodiesterases (PDEs) control c-di-GMP homeostasis in the cell. Many microbes have a large number of genes encoding DGCs and PDEs that are predict...

Biofilm formation and phenotypic variation enhance predation-driven persistence of Vibrio cholerae.

Published in Proceedings of the National Academy of Sciences

Persistence of the opportunistic bacterial pathogen Vibrio cholerae in aquatic environments is the principal cause for seasonal occurrence of cholera epidemics. This causality has been explained by postulating that V. cholerae forms biofilms in association with animate and inanimate surfaces. Alternatively, it has been proposed that bacterial patho...

Species-dependent hydrodynamics of flagellum-tethered bacteria in early biofilm development.

Published in Journal of The Royal Society Interface

Monotrichous bacteria on surfaces exhibit complex spinning movements. Such spinning motility is often a part of the surface detachment launch sequence of these cells. To understand the impact of spinning motility on bacterial surface interactions, we develop a hydrodynamic model of a surface-bound bacterium, which reproduces behaviours that we obse...

Role of Vibrio polysaccharide (vps) genes in VPS production, biofilm formation and Vibrio cholerae pathogenesis.

Published in Microbiology

Biofilm formation enhances the survival and persistence of the facultative human pathogen Vibrio cholerae in natural ecosystems and its transmission during seasonal cholera outbreaks. A major component of the V. cholerae biofilm matrix is the Vibrio polysaccharide (VPS), which is essential for development of three-dimensional biofilm structures. Th...

Genetic analysis of photosynthesis in Rhodospirillum centenum.

Published in Journal of Bacteriology

A genetic system has been developed for studying bacterial photosynthesis in the recently described nonsulfur purple photosynthetic bacterium Rhodospirillum centenum. Nonphotosynthetic mutants of R. centenum were obtained by enrichment for spontaneous mutations, by ethyl methanesulfonate mutagenesis coupled to penicillin selection on solid medium, ...

Identification and characterization of cyclic diguanylate signaling systems controlling rugosity in Vibrio cholerae.

Published in Journal of Bacteriology

Vibrio cholerae, the causative agent of the disease cholera, can generate rugose variants that have an increased capacity to form biofilms. Rugosity and biofilm formation are critical for the environmental survival and transmission of the pathogen, and these processes are controlled by cyclic diguanylate (c-di-GMP) signaling systems. c-di-GMP is pr...

Inferring disease-related pathways using a probabilistic epistasis model.

Published in Pacific Symposium on Biocomputing. Pacific Symposium on Biocomputing

Molecular determinants of mechanical properties of V. cholerae biofilms at the air-liquid interface.

Published in Biophysical Journal

Biofilm formation increases both the survival and infectivity of Vibrio cholerae, the causative agent of cholera. V. cholerae is capable of forming biofilms on solid surfaces and at the air-liquid interface, termed pellicles. Known components of the extracellular matrix include the matrix proteins Bap1, RbmA, and RbmC, an exopolysaccharide termed V...

Phenotypic analysis reveals Haiti cholera epidemic linked to hypervirulent strain.

Published in Infection and Immunity

Identification and characterization of a phosphodiesterase that inversely regulates motility and biofilm formation in Vi...

Published in Journal of Bacteriology

Vibrio cholerae switches between free-living motile and surface-attached sessile lifestyles. Cyclic diguanylate (c-di-GMP) is a signaling molecule controlling such lifestyle changes. C-di-GMP is synthesized by diguanylate cyclases (DGCs) that contain a GGDEF domain and is degraded by phosphodiesterases (PDEs) that contain an EAL or HD-GYP domain. W...

VpsR, a Member of the Response Regulators of the Two-Component Regulatory Systems, Is Required for Expression of vps Bio...

Published in Journal of Bacteriology

The rugose colonial variant of Vibrio cholerae O1 El Tor produces an exopolysaccharide (EPS(ETr)) that enables the organism to form a biofilm and to resist oxidative stress and the bactericidal action of chlorine. Transposon mutagenesis of the rugose variant led to the identification of vpsR, which codes for a homologue of the NtrC subclass of resp...

Regulation of rugosity and biofilm formation in Vibrio cholerae: comparison of VpsT and VpsR regulons and epistasis anal...

Published in Journal of Bacteriology

Vibrio cholerae undergoes phenotypic variation that generates two morphologically different variants, termed smooth and rugose. The transcriptional profiles of the two variants differ greatly, and many of the differentially regulated genes are controlled by a complex regulatory circuitry that includes the transcriptional regulators VpsR, VpsT, and ...

The transcriptional regulator, CosR, controls compatible solute biosynthesis and transport, motility and biofilm formati...

Published in Environmental Microbiology

Vibrio cholerae inhabits aquatic environments and colonizes the human digestive tract to cause the disease cholera. In these environments, V. cholerae copes with fluctuations in salinity and osmolarity by producing and transporting small, organic, highly soluble molecules called compatible solutes, which counteract extracellular osmotic pressure. C...

Characterization of Sulfate Transport in Chlamydomonas reinhardtii during Sulfur-Limited and Sulfur-Sufficient Growth.

Published in PLANT PHYSIOLOGY

We have characterized sulfate transport in the unicellular green alga Chlamydomonas reinhardtii during growth under sulfur-sufficient and sulfur-deficient conditions. Both the Vmax and the substrate concentration at which sulfate transport is half of the maximum velocity of the sulfate transport (K1/2) for uptake were altered in starved cells: the ...

VpsT is a transcriptional regulator required for expression of vps biosynthesis genes and the development of rugose colo...

Published in Journal of Bacteriology

Vibrio cholerae switches between smooth and rugose colonial variants. The rugose variant produces more vibrio polysaccharides (VPS(El Tor)) and forms well-developed biofilms. Both phenotypes depend on expression of vps biosynthesis genes. We identified a positive transcriptional regulator of vps gene expression, VpsT, which is homologous to respons...

Discovery and biological characterization of the auromomycin chromophore as an inhibitor of biofilm formation in Vibrio ...

Published in ChemBioChem

Bacterial biofilms pose a significant challenge in clinical environments due to their inherent lack of susceptibility to antibiotic treatment. It is widely recognized that most pathogenic bacterial strains in the clinical setting persist in the biofilm state, and are the root cause of many recrudescent infections. The discovery and development of c...