X-ray crystal structure of MENT: evidence for functional loop-sheet polymers in chromatin condensation. (2H4R)
Version 2 2016-12-11, 22:36Version 2 2016-12-11, 22:36
Version 1 2016-05-23, 04:50Version 1 2016-05-23, 04:50
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posted on 2016-12-11, 22:36authored byAshley Buckle, JA Irving, Sheena McGowan, James Whisstock
Most serpins are associated with protease inhibition, and their ability to form loop-sheet polymers is linked to conformational disease and the human serpinopathies. Here we describe the structural and functional dissection of how a unique serpin, the non-histone architectural protein, MENT (Myeloid and Erythroid Nuclear Termination stage-specific protein), participates in DNA and chromatin condensation. Our data suggest that MENT contains at least two distinct DNA-binding sites, consistent with its simultaneous binding to the two closely juxtaposed linker DNA segments on a nucleosome. Remarkably, our studies suggest that the reactive centre loop, a region of the MENT molecule essential for chromatin bridging in vivo and in vitro, is able to mediate formation of a loop-sheet oligomer. These data provide mechanistic insight into chromatin compaction by a non-histone architectural protein and suggest how the structural plasticity of serpins has adapted to mediate physiological, rather than pathogenic, loop-sheet linkages.