Meiotic Recombination in Neurospora crassa Proceeds by Two Pathways with Extensive Holliday Junction Migration

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Date
2016
Authors
Yeadon, Patricia Jane
Bowring, Frederick James
Catcheside, David Edward
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Public Library of Science
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Copyrigh: © 2016 Yeadon et al.
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Abstract
Analysis of thousands of Δmsh-2 octads using our fluorescent recombination system indicates that, as in other filamentous fungi, symmetric heteroduplex is common in the his-3 region of Neurospora crassa. Symmetric heteroduplex arises from Holliday junction migration, and we suggest this mechanism explains the high frequency of His+ spores in heteroallelic crosses in which recombination is initiated cis to the his-3 allele further from the initiator, cog+. In contrast, when recombination is initiated cis to the his-3 allele closer to cog+, His+ spores are mainly a result of synthesis-dependent strand annealing, yielding asymmetric heteroduplex. Loss of Msh-2 function increases measures of allelic recombination in both his-3 and the fluorescent marker gene, indicating that mismatches in asymmetric heteroduplex, as in Saccharomyces cerevisiae, tend to be repaired in the direction of restoration. Furthermore, the presence of substantial numbers of conversion octads in crosses lacking Msh-2 function suggests that the disjunction pathway described in S. cerevisiae is also active in Neurospora, adding to evidence for a universal model for meiotic recombination.
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This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Yeadon PJ, Bowring FJ, Catcheside DEA (2016) Meiotic Recombination in Neurospora crassa Proceeds by Two Pathways with Extensive Holliday Junction Migration. PLoS ONE 11(1): e0147815. doi:10.1371/journal.pone.0147815