Xchromosome and autosomal recombination are differentially sensitive to disruptions in SC maintenance

Abstract

22In Drosophila, meiotic recombination is initiated by the formation of programmed DNA double-23 strand breaks (DSBs), which occur within the context of the synaptonemal complex (SC). To 24 better understand the role of the SC in mediating recombination we created an in-frame deletion suggesting that discontinuity in the euchromatic SC-rather than failed pairing-might cause the 39 altered crossover distribution. These phenotypes reveal that different chromatin states or 40 regions have differing requirements to maintain both the SC and homologous pairing. 41

Unconventional conservation reveals structure-function relationships in the synaptonemal complex

“…In the SC, the strong selection acting on coiled-coils likely reflects biophysical and structural properties that are conserved across phyla. Coiled-coils in transverse filament proteins help determine the 100nm space between the parental chromosomes (13, 15). However, this role by itself cannot explain the prevalence and conservation of coiled-coils in SC proteins that are not transverse filaments.…”

“…1A). SC proteins with this orientation are referred to as 'transverse filaments' and help determine the width of the SC via a central coiled-coil domain (13)(14)(15)(16). Thus, SC proteins represent a case where functional and ultrastructural conservation does not seem to constrain a protein's primary sequence -a pattern that, although unconventional for essential proteins, is likely to be more prevalent than is currently appreciated (17).…”