Saccharomyces cerevisiae cells lacking the homologous pairing protein p175(SEP1) arrest at pachytene during meiotic prophase

Saccharomyces cerevisiae cells containing null mutations in the SEP1 gene, which encodes the homologous pairing and strand exchange protein pl75sep1, enter pachytene with a delay. They arrest uniformly at this stage of meiotic prophase, probably revealing a checkpoint in the transition from pachyten...

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Bibliographic Details
Published in:Chromosoma 1994-04, Vol.103 (2), p.129-141
Main Authors: Bahler, J, Hagens, G, Holzinger, G, Scherthan, H, Heyer, W.D
Format: Article
Language:English
Subjects:
crossing over
DNA-binding proteins
gene conversion
homologous recombination
intragenic recombination
meiosis
mutagenesis
mutants
null mutations
prophase
Saccharomyces cerevisiae
sep1 gene
structural genes
synaptonemal complex
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Summary:Saccharomyces cerevisiae cells containing null mutations in the SEP1 gene, which encodes the homologous pairing and strand exchange protein pl75sep1, enter pachytene with a delay. They arrest uniformly at this stage of meiotic prophase, probably revealing a checkpoint in the transition from pachytene to meiosis 1. At the arrest point, the cells remain largely viable and are cytologically characterized by the duplicated but unseparated spindle pole bodies of equal size and by the persistence of the synaptonemal complex, a cytological marker for pachytene. In addition, fluorescence in situ hybridization revealed that in arrested mutant cells maximal chromatin condensation and normal homolog pairing is achieved, typical for pachytene in wild type. A hallmark of meiosis is the high level of homologous recombination, which was analyzed both genetically and physically. Formation and processing of the double-strand break intermediate in meiotic recombination is achieved prior to arrest. Physical intragenic (conversion) and intergenic (crossover) products are formed just prior to, or directly at, the arrest point. Structural deficits in synaptonemal complex morphology, failure to separate spindle pole bodies, and/or defects in prophase DNA metabolism might be responsible for triggering the observed arrest. The pachytene arrest in sep] cells is likely to be regulatory, but is clearly different from the RAD9 checkpoint in meiotic prophase, which occurs prior to the pachytene stage.
ISSN:0009-5915
1432-0886
DOI:10.1007/BF00352322