Gene Conversion

Stahl, Franklin W.

doi:10.1016/b978-0-12-374984-0.00584-2

Cited by 1 publication

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“…These were described in the Smith model [ 154 ] by a non-reciprocal recombination between homologous sequences that are neutral to selection [ 155 , 156 , 157 ]. Similarly, the mechanism of gene conversion (GC) ( Figure 3 B) [ 158 ] is a unidirectional transfer of genetic information from an intact to a broken strand, and can readily account for centromere expansion driven by DNA damage. Depending on the length of GC tracts, they can be called short-tract gene conversions (STGC) for DNA segments ranging between 50 to 200 bp [ 159 , 160 ] or long-tract gene conversions (LTGC) for segments over 1 kb [ 161 , 162 ], with LTGC likely playing a role at large centromeres.…”

Section: Mapping Mutagenic Mechanisms By Following Their Evolutionmentioning

confidence: 99%

Centromeres under Pressure: Evolutionary Innovation in Conflict with Conserved Function

Balzano

Giunta

2020

Genes

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Centromeres are essential genetic elements that enable spindle microtubule attachment for chromosome segregation during mitosis and meiosis. While this function is preserved across species, centromeres display an array of dynamic features, including: (1) rapidly evolving DNA; (2) wide evolutionary diversity in size, shape and organization; (3) evidence of mutational processes to generate homogenized repetitive arrays that characterize centromeres in several species; (4) tolerance to changes in position, as in the case of neocentromeres; and (5) intrinsic fragility derived by sequence composition and secondary DNA structures. Centromere drive underlies rapid centromere DNA evolution due to the “selfish” pursuit to bias meiotic transmission and promote the propagation of stronger centromeres. Yet, the origins of other dynamic features of centromeres remain unclear. Here, we review our current understanding of centromere evolution and plasticity. We also detail the mutagenic processes proposed to shape the divergent genetic nature of centromeres. Changes to centromeres are not simply evolutionary relics, but ongoing shifts that on one side promote centromere flexibility, but on the other can undermine centromere integrity and function with potential pathological implications such as genome instability.

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