Publications by authors named "Oleksii Lyzak"

2 Publications

  • Page 1 of 1

Deprotection of centromeric cohesin at meiosis II requires APC/C activity but not kinetochore tension.

EMBO J 2021 Apr 1;40(7):e106812. Epub 2021 Mar 1.

Laboratory of Chromosome Biology, Max Planck Institute of Biochemistry, Martinsried, Germany.

Genome haploidization involves sequential loss of cohesin from chromosome arms and centromeres during two meiotic divisions. At centromeres, cohesin's Rec8 subunit is protected from separase cleavage at meiosis I and then deprotected to allow its cleavage at meiosis II. Protection of centromeric cohesin by shugoshin-PP2A seems evolutionarily conserved. However, deprotection has been proposed to rely on spindle forces separating the Rec8 protector from cohesin at metaphase II in mammalian oocytes and on APC/C-dependent destruction of the protector at anaphase II in yeast. Here, we have activated APC/C in the absence of sister kinetochore biorientation at meiosis II in yeast and mouse oocytes, and find that bipolar spindle forces are dispensable for sister centromere separation in both systems. Furthermore, we show that at least in yeast, protection of Rec8 by shugoshin and inhibition of separase by securin are both required for the stability of centromeric cohesin at metaphase II. Our data imply that related mechanisms preserve the integrity of dyad chromosomes during the short metaphase II of yeast and the prolonged metaphase II arrest of mammalian oocytes.
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http://dx.doi.org/10.15252/embj.2020106812DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8013787PMC
April 2021

Role of the regulatory genes SEF1, VMA1 and SFU1 in riboflavin synthesis in the flavinogenic yeast Candida famata (Candida flareri).

Yeast 2020 09 2;37(9-10):497-504. Epub 2020 Jul 2.

Department of Molecular Biology and Biotechnology, Institute of Cell Biology, National Academy of Sciences of Ukraine, Lviv, Ukraine.

Riboflavin or vitamin B is an essential dietary component for humans and animals that is the precursor of flavin coenzymes flavin mononucleotide and flavin adenine dinucleotide involved in numerous enzymatic reactions. The flavinogenic yeast Candida famata overproduces riboflavin under iron starvation; however, regulation of this process is poorly understood. Regulatory gene SEF1 encoding transcription activator has been identified. Its deletion blocks yeast ability to overproduce riboflavin under iron starvation. It was shown here that the SEF1 promoters from other flavinogenic (Candida albicans) and non-flavinogenic (Candida tropicalis) yeasts fused with the open reading frame (ORF) of SEF1 gene from C. famata are able to restore riboflavin oversynthesis in sef1Δ mutants. It is known that in the pathogenic flavinogenic yeast C. albicans, Sfu1 (GATA-type transcription factor) represses SEF1. Here, we found that deletion of SFU1 gene in wild-type C. famata leads to riboflavin oversynthesis. Moreover, it was shown that disruption of VMA1 gene (coding for vacuolar ATPase subunit A) also results in riboflavin oversynthesis in C. famata.
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http://dx.doi.org/10.1002/yea.3503DOI Listing
September 2020