Dynamics of homology searching during gene conversion in Saccharomyces cerevisiae revealed by donor competition.
نویسندگان
چکیده
One of the least understood aspects of homologous recombination is the process by which the ends of a double-strand break (DSB) search the entire genome for homologous templates that can be used to repair the break. We took advantage of the natural competition between the alternative donors HML and HMR employed during HO endonuclease-induced switching of the budding yeast MAT locus. The strong mating-type-dependent bias in the choice of the donors is enforced by the recombination enhancer (RE), which lies 17 kb proximal to HML. We investigated factors that improve the use of the disfavored donor. We show that the normal heterochromatic state of the donors does not impair donor usage, as donor choice is not affected by removing this epigenetic silencing. In contrast, increasing the length of homology shared by the disfavored donor increases its use. This result shows that donor choice is not irrevocable and implies that there are several encounters between the DSB ends and even the favored donor before recombination is accomplished. The increase by adding more homology is not linear; these results can be explained by a thermodynamic model that determines the energy cost of using one donor over the other. An important inference from this analysis is that when HML is favored as the donor, RE causes a reduction in its effective genomic distance from MAT from 200 kb to ∼20 kb, which we hypothesize occurs after the DSB is created, by epigenetic chromatin modifications around MAT.
منابع مشابه
Isolation, Subtype Determination, Cloning and Expression of HBsAg Gene from an Iranian Carrier in Saccharomyces cerevisiae
The Hepatitis B Surface antigen ( HBsAg) gene was isolated from an Iranian HBeAg positive carrier by PCR. The gene was cloned in pUC19 for sequencing and pYES2 for expression in Saccharomyces cerevisiae, which pNF1 and pDF3 constructs were made respectively. The sequencing data showed that the isolated HBsAg gene shared more than 90% homology with the ayw subtype. The pDF3 was transferred into ...
متن کاملThe Saccharomyces cerevisiae recombination enhancer biases recombination during interchromosomal mating-type switching but not in interchromosomal homologous recombination.
Haploid Saccharomyces can change mating type through HO-endonuclease cleavage of an expressor locus, MAT, followed by gene conversion using one of two repository loci, HML or HMR, as donor. The mating type of a cell dictates which repository locus is used as donor, with a cells using HML and alpha cells using HMR. This preference is established in part by RE, a locus on the left arm of chromoso...
متن کاملInhibitory Effect of Supernatant and Lysate of Saccharomyces cerevisiae on Expression of exoA Gene of Pseudomonas aeruginosa
Background and Aim: Pseudomonas aeruginosa is an important ubiquitous and especially common pathogen in the hospital. Exotoxin A that encoded by exoA gene has a role in pathogenesis of this bacterium. Today, probiotics are widely used in the treatment and prevention of diseases. The present study aimed to study the Saccharomyces cerevisiae S3 effect on the expression of exoA gene. Materials an...
متن کاملInitiation of Ageing Process by Meiotic and Mitotic Recombination within the Ribosomal DNA Genes in Saccharomyces cerevisiae
In the budding yeast of Saccharomyces cerevisiae the tandem repeated of rDNA genes are located onchromosome XII, which is in the nucleolus. There are different types of proteins in the nucleoluskeleton,silencing proteins have got important role in nucleolus.It is shown that meiotic recombination between nonsister chromatids in the rDNA genes are stronglysuppressed, and s...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Genetics
دوره 189 4 شماره
صفحات -
تاریخ انتشار 2011