 |
Fitnat Yildiz
Associate Professor of Environmental Toxicology
B.S, Biology, Hacettepe University, Ankara, Turkey
Ph.D., Microbiology & Molecular Biology, Indiana University
Postdoctoral Fellow, Stanford University, School of Medicine
Office: 444 PSB, Office
Hours: By
Appointment
Email: yildiz@etox.ucsc.edu
Office
Phone: (831) 459-1588
Lab Phone: |
Research Group: Yildiz Lab
Microbiology, molecular genetics, genomics. The mechanism of
persistence and survival of Vibrio cholerae.
Ex-vivo
survival mechanisms used by Vibrio cholerae between epidemics
Alterations
to aquatic environments, via natural or anthropogenic factors can
directly or indirectly lead to infectious disease outbreaks. At
present, little information is available on the molecular ecology
and evolutionary dynamics of infectious agents in the environment.
Understandingtheenvironmental factors involved in persistence,
growth, and transmission of pathogens and the response of organisms
to environmental changes will provide information about the emergence
or re-emergence of infectious diseases.
Vibrio
cholerae, the causative agent of the Asiatic cholera, is
an excellent model system to study these processes, because V.
cholerae causes periodic, seasonal outbreaks in regions where
it is an established member of the indigenous aquatic flora.
It is estimated that the disease causes the death of 120,000
people worldwide every year. V. choleraeÍs capacity to
cause seasonal epidemics is linked to its survival in free-living
and in biofilm growth modes in aquatic environments between outbreaks.
However, the processes governing the survival of V. cholerae and
its adaptability to changes in habitat remain elusive.
V.
cholerae has two phase variants which are named as smooth
and rugose reflecting the appearance of their colonial morphologies.
Reversible phase variation between the rugose and the smooth
colonial variants and associated phenotypes are postulated to
be an important factor for the survival of the organism. Little
is known about the molecular basis of the phase variation and
molecular differences between these two colonial variants. Using
molecular genetic and genomic approaches we are working towards
identification and characterization of the genes and the processes
that are associated with the phase variation.
In aquatic
habitats V. cholerae is found as attached to various biotic
and abiotic surfaces. It has been proposed that attachment of bacteria
to surfaces, and subsequent biofilm growth mode, exemplifies a
survival strategy. Identification of the genes required for the
development of V. cholerae biofilms and of metabolic pathways
operating in these biofilms is central to understanding of the
sessile lifecycle of the organism. We know very little about the
processes that allow V. cholerae to sense, respond, and
adapt to a life on a surface. We are studying the signals and regulatory
networks that are essential for biofilm formation by V. cholerae by
employing the combined use of molecular genetics, functional genomics,
proteomics, microbial ecology and microscopy.
Results
obtained through these projects will expand our understanding of
the environmental life cycle of an important human pathogen and
will provide information useful for the prediction and control
of cholera epidemics.
Selected
Publications
Manuscripts:
Yildiz, F. H., and Schoolnik, G. K. (1998) Role of rpoS in Stress survival and virulence of Vibrio cholerae. J. Bacteriol. 180: 773-784.
Yildiz, F. H., and Schoolnik, G. K. (1999) Vibrio cholerae O1 El Tor: Identification of a gene cluster required for the rugose colony type, exopolysaccharide production, chlorine resistance, and biofilm formation. Proc. Natl. Acad. Sci. USA 96: 4028-4033.
Yildiz, F. H., Dolganov, N.A., and Schoolnik, G. K. (2001) VpsR, a member of the response regulators of the two-component regulatory systems, is required for expression of vps biosynthesis genes and the VPS associated phenotypes in Vibrio cholerae O1 El Tor. J. Bacteriol. 183: 1716-26.
Casper-Lindley and Yildiz, F. H. (2004). VpsT is a transcriptional regulator required for the rugose colonial morphology of Vibrio cholerae O1 El Tor. Journal of Bacteriology. 186: 1574-78.
Yildiz, F. H., Xiaole, S. H., Heydorn A. and Schoolnik, G. K. (2004). Molecular analysis of Rugosity in Vibrio cholerae O1 El Tor. phase variant. Molecular Microbiology. 53(2), 497-515.
Carsten Matz, Diane McDougald , Ana Maria Moreno , Pui Yi Yung , Fitnat H. Yildiz and Staffan Kjelleberg. (2005). Biofilm formation and phenotypic variation enhance predation-driven persistence of Vibrio cholerae. PNAS, 102(46):16819-24.
Fong JC, Karplus K, Schoolnik GK, Yildiz FH. (2006) Identification and characterization of RbmA, a novel protein required for the development of rugose colony morphology and biofilm structure in Vibrio cholerae. J Bacteriol.188(3):1049-59.
Lim B, Beyhan S, Meir J, Yildiz FH. (2006) Cyclic-diGMP signal transduction systems in Vibrio cholerae: modulation of rugosity and biofilm formation. Mol Microbiol. 60(2):331-48.
Beyhan S, Tischler AD, Camilli A, Yildiz FH. (2006) Transcriptome and phenotypic responses of Vibrio cholerae to increased cyclic di-GMP level.J Bacteriol. 188(10):3600-13.
Beyhan S, Tischler AD, Camilli A, Yildiz FH (2006) Differences in gene expression between the classical and El Tor biotypes of Vibrio cholerae O1.Infect Immun. 2006 74(6):3633-42.
Beyhan S, Bilecen K, Salama SR, Casper-Lindley C and Yildiz FH (2007) Regulation of rugosity and biofilm formation in Vibrio cholerae: Comparison of VpsT and VpsR regulons and epistasis analysis of vpsT, vpsR and hapR. J Bacteriol. 189(2):388-402.
Lim B, Beyhan S and Yildiz FH (2007) Regulation of Vibrio polysaccharide synthesis and virulence factor production by CdgC, a GGDEF-EAL domain protein, in Vibrio cholerae J Bacteriol. 189(6):2319-30.
Fong, JC and Yildiz, F.H. (2007) The rbmBCDEF Gene Cluster Modulates Development of Rugose Colony Morphology and Biofilm Formation in Vibrio cholerae. J Bacteriol. 189(6):2319-30.
Beyhan S and Yildiz FH (2007) Phenotypic variation in Vibrio cholerae is mediated by a single nucleotide change that targets c-di-GMP signaling pathway and alters phage susceptibility. Mol Microbiol. 63(4):995-1007.
Reviews and Book Chapters
Schoolnik, G. K., and Yildiz, F. H. (2000) The complete genome sequence of Vibrio cholerae: a tale of two chromosomes and two lifestyles. Genome Biology 1(3): 1016.1-1016.3.
Yildiz FH (2007) Processes controlling the transmission of bacterial pathogens in the environment, Res Microbiol. 158(3):195-202.
Schoolnik, G. K., Voskuil, M. I., Schnappinger, D., Yildiz, F. H., Meibom, K., Dolganov, A. N., Wilson, M.A., Chong, K. H. (2000) Whole genome DNA microarray expression analysis of biofilm development by Vibrio cholerae O1 El Tor. In Microbial growth in biofilms, Part A. Edited by Doyle RJ. San Diego, CA: Academic Press; Methods in Enzymology. 336:3-18.
Flanders, J.R., and Yildiz, F. H. (2004) Biofilms as a Reservoir for Disease, Chapter 17. In: Introduction to Biofilms: Conceptual Themes, George A. O’Toole and Mahmoud A. Ghannoum, eds. ASM Press, Washington DC.
Yildiz F. H., and Kolter, R. (2007) Genetics and Microbiology of biofilm formation in Vibrio cholerae. In : Vibrio cholerae: Genomics and Molecular Biology, Shah M. Faruque and G. Balakrish Nair, eds. The Horizon Scientific Press. (In press).
|
