Tetracycline-Regulatable System To Tightly Control Gene Expression in the Pathogenic Fungus
            <i>Candida albicans</i>

Nakayama, Hironobu; Mio, Toshiyuki; Nagahashi, Shigehisa; Kokado, Michiko; Arisawa, Mikio; Aoki, Yuko

doi:10.1128/iai.68.12.6712-6719.2000

Cited by 150 publications

(162 citation statements)

References 23 publications

(30 reference statements)

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“…It was constructed as follows: A fragment containing pENO plus tetR-ScHAP4-WH11 was amplified by PCR from the plasmid pCAITHE5 (Nakayama et al 2000) with primers ENOpf and tetRWH11pr (the sequences of all primers used are given in Table S1). The fragment was cloned into SmaI-linearized plasmid pBSKS (+) to produce plasmid pNZ1.…”

Section: Resistance Cassettes For Selection Of Fusantsmentioning

confidence: 99%

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Selective Advantages of a Parasexual Cycle for the YeastCandida albicans

Zhang

Magee

et al. 2015

Genetics

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The yeast Candida albicans can mate. However, in the natural environment mating may generate progeny (fusants) fitter than clonal lineages too rarely to render mating biologically significant: C. albicans has never been observed to mate in its natural environment, the human host, and the population structure of the species is largely clonal. It seems incapable of meiosis, and most isolates are diploid and carry both mating-type-like (MTL) locus alleles, preventing mating. Only chromosome loss or localized loss of heterozygosity can generate mating-competent cells, and recombination of parental alleles is limited. To determine if mating is a biologically significant process, we investigated if mating is under selection. The ratio of nonsynonymous to synonymous mutations in mating genes and the frequency of mutations abolishing mating indicated that mating is under selection. The MTL locus is located on chromosome 5, and when we induced chromosome 5 loss in 10 clinical isolates, most of the resulting MTL-homozygotes could mate with each other, producing fusants. In laboratory culture, a novel environment favoring novel genotypes, some fusants grew faster than their parents, in which loss of heterozygosity had reduced growth rates, and also faster than their MTL-heterozygous ancestors-albeit often only after serial propagation. In a small number of experiments in which co-inoculation of an oral colonization model with MTL-homozygotes yielded small numbers of fusants, their numbers declined over time relative to those of the parents. Overall, our results indicate that mating generates genotypes superior to existing MTL-heterozygotes often enough to be under selection.KEYWORDS Candida albicans; mating; parasexual cycle; cryptic sexual cycle S EX is costly and disrupts well-adapted allele combinations. It can also be advantageous by speeding up adaptation or by purging deleterious mutations. It has been difficult to establish how, precisely, these and other benefits outweigh the cost of sex. Indeed, abandoning sex in favor of clonal reproduction can be advantageousasexual species arise frequently. Their life spans are short, however, indicating that sex may be essential for the long-term survival of species (Otto and Lenormand 2002;Rice 2002).Sexual cycles have not been observed for 20% of fungal species (Carlile et al. 2001). Whether these species are truly asexual or merely restrict the frequency of sex-a strategy believed to maximize its benefits (Heitman 2006)-is difficult to determine. Genetic marker distributions in such species often suggest limited recombination (Carlile et al. 2001). However, clonal reproduction will initially copy the genetic marker distributions that were generated by sex, and new mutations and genetic drift will only slowly erase evidence of past recombination (Schmid et al. 2004;Cox et al. 2013). With rare exceptions, fungi without observable sexual cycles are derived from recent sexual ancestors (Carlile et al. 2001;Schmid et al. 2004;Butler 2007). Thus genetic marker distributi...

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Section: Resistance Cassettes For Selection Of Fusantsmentioning

confidence: 99%

“…The fragment was cloned into SmaI-linearized plasmid pBSKS (+) to produce plasmid pNZ1. The tetracycline-responsive promoter (pTR) was PCR amplified from plasmid p99RLU (Nakayama et al 2000) with primers TRpf and TRpr. The IMH3 r ORF was amplified from plasmid p3408 ) using primers IMH3pfatg and IMH3pr.…”

Section: Resistance Cassettes For Selection Of Fusantsmentioning

confidence: 99%

Selective Advantages of a Parasexual Cycle for the YeastCandida albicans

Zhang

Magee

et al. 2015

Genetics

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“…Overexpression of candidate genes can therefore be used to complement studies of gene disruption [150]. A number of regulatable promoters have been developed to regulate gene expression, including the MET3 promoter [151], the MAL2 promoter [152] and tetracyclineregulated promoters (Tet-OFF and Tet-ON) [153,154]. A library of overexpression strains was constructed in a Tet-ON system for 107 putative transcription factors, most with a known biological role [155].…”

Section: Construction Of Systematic Strain Collectionsmentioning

confidence: 99%

Budding off: bringing functional genomics toCandida albicans

Anderson¹,

Bennett²

2015

Briefings in Functional Genomics

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Candida species are the most prevalent human fungal pathogens, with Candida albicans being the most clinically relevant species. Candida albicans resides as a commensal of the human gastrointestinal tract but is a frequent cause of opportunistic mucosal and systemic infections. Investigation of C. albicans virulence has traditionally relied on candidate gene approaches, but recent advances in functional genomics have now facilitated global, unbiased studies of gene function. Such studies include comparative genomics (both between and within Candida species), analysis of total RNA expression, and regulation and delineation of protein-DNA interactions. Additionally, large collections of mutant strains have begun to aid systematic screening of clinically relevant phenotypes. Here, we will highlight the development of functional genomics in C. albicans and discuss the use of these approaches to addressing both commensalism and pathogenesis in this species.

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“…In addition to the endogenous C. albicans promoters described above, a heterologous, tetracycline-regulatable expression system has been adapted for use in C. albicans (77). This system utilizes two components.…”

Section: Conditional Mutantsmentioning

confidence: 99%