Editing Candida albicans (section)

===White-opaque switching===

Next to the [[sexual dimorphism|dimorphism]] and the first described high-frequency switching system ''C. albicans'' undergoes another high-frequency switching process called white-opaque switching, which is another [[phenotypic switching]] process in ''C. albicans''. It was the second high-frequency switching system discovered in ''C. albicans''.<ref name="auto"/> The white-opaque switch is an [[Epigenetics|epigenetic]] switching system.<ref name="ReferenceA">{{cite journal | vauthors = Rikkerink EH, Magee BB, Magee PT | title = Opaque-white phenotype transition: a programmed morphological transition in Candida albicans | journal = Journal of Bacteriology | volume = 170 | issue = 2 | pages = 895–899 | date = February 1988 | pmid = 2828333 | pmc = 210739 | doi = 10.1128/jb.170.2.895-899.1988 }}</ref> Phenotypic switching is often used to refer to white-opaque switching, which consists of two phases: one that grows as round cells in smooth, white colonies (referred to as white form) and one that is rod-like and grows as flat, gray colonies (called opaque form). This switch between white cells and opaque cells is important for the virulence and the [[mating of yeast|mating]] process of ''C. albicans'' as the opaque form is the [[mating in fungi|mating]] competent form, being a million times more efficient in mating compared to the white type.<ref name="ReferenceA"/><ref>{{cite journal | vauthors = Lohse MB, Johnson AD | title = White-opaque switching in Candida albicans | journal = Current Opinion in Microbiology | volume = 12 | issue = 6 | pages = 650–654 | date = December 2009 | pmid = 19853498 | pmc = 2812476 | doi = 10.1016/j.mib.2009.09.010 }}</ref><ref>{{cite book |vauthors=Hnisz D, Tscherner M, Kuchler K |title=Yeast Genetic Networks |chapter=Morphological and Molecular Genetic Analysis of Epigenetic Switching of the Human Fungal Pathogen Candida albicans |volume=734 |issue=2 |pages=303–315 |year=2011 |doi=10.1007/978-1-61779-086-7_15|pmid=21468996|series=Methods in Molecular Biology |isbn=978-1-61779-085-0}}</ref> This switching between white and opaque form is regulated by the WOR1 regulator (White to Opaque Regulator 1) which is controlled by the [[mating type]] locus (MTL) repressor (a1-α2) that inhibits the expression of WOR1.<ref>{{cite journal | vauthors = Morschhäuser J | title = Regulation of white-opaque switching in Candida albicans | journal = Medical Microbiology and Immunology | volume = 199 | issue = 3 | pages = 165–172 | date = August 2010 | pmid = 20390300 | doi = 10.1007/s00430-010-0147-0 | s2cid = 8770123 }}</ref> Besides the white and opaque phase there is also a third one: the gray phenotype. This phenotype shows the highest ability to cause cutaneous infections. The white, opaque, and gray phenotypes form a phenotypic switching system where white cells switch to and from the opaque phase, white cells can irreversibly switch to the gray phase, and both white and gray cells can switch to and from the opaque/an opaque-like phase, respectively.<ref name="ReferenceC">{{cite journal | vauthors = Tao L, Du H, Guan G, Dai Y, Nobile CJ, Liang W, Cao C, Zhang Q, Zhong J, Huang G | display-authors = 6 | title = Discovery of a "white-gray-opaque" tristable phenotypic switching system in candida albicans: roles of non-genetic diversity in host adaptation | journal = PLOS Biology | volume = 12 | issue = 4 | pages = e1001830 | date = April 2014 | pmid = 24691005 | pmc = 3972085 | doi = 10.1371/journal.pbio.1001830 | doi-access = free }}</ref><ref name="Hemizygosity enables a mutational t">{{cite journal | vauthors = SLiang SH, Anderson MZ, Hirakawa MP, Wang JM, Frazer C, Alaalm LM, Thomson GJ, Ene IV, Bennett RJ | title = Hemizygosity enables a mutational transition governing fungal virulence and commensalism | journal = Cell Host Microbe | volume = 25 | issue = 3 | pages = 418–431.e6 | date = March 2019 | pmid = 30824263 | pmc = 6624852 | doi = 10.1016/j.chom.2019.01.005 }}</ref> Since it is often difficult to differentiate between white, opaque and gray cells phloxine B, a dye, can be added to the medium.<ref name="ReferenceC"/>

A potential regulatory molecule in the white to opaque switching is ''Efg1p'', a [[transcription factor]] found in the WO-1 strain that regulates dimorphism, and more recently has been suggested to help regulate phenotypic switching. ''Efg1p'' is expressed only in the white and not in the gray cell-type, and overexpression of ''Efg1p'' in the gray form causes a rapid conversion to the white form.<ref>{{cite journal | vauthors = Sonneborn A, Tebarth B, Ernst JF | title = Control of white-opaque phenotypic switching in Candida albicans by the Efg1p morphogenetic regulator | journal = Infection and Immunity | volume = 67 | issue = 9 | pages = 4655–4660 | date = September 1999 | pmid = 10456912 | pmc = 96790 | doi = 10.1128/IAI.67.9.4655-4660.1999 }}</ref><ref>{{cite journal | vauthors = Srikantha T, Tsai LK, Daniels K, Soll DR | title = EFG1 null mutants of Candida albicans switch but cannot express the complete phenotype of white-phase budding cells | journal = Journal of Bacteriology | volume = 182 | issue = 6 | pages = 1580–1591 | date = March 2000 | pmid = 10692363 | pmc = 94455 | doi = 10.1128/JB.182.6.1580-1591.2000 }}</ref><ref name="Hemizygosity enables a mutational t"/>