PMID: 16810322

Authors:

McGowan S, Buckle AM, Irving JA, Ong PC, Bashtannyk-Puhalovich TA, Kan WT, Henderson KN, Bulynko YA, Popova EY, Smith AI, Bottomley SP, Rossjohn J, Grigoryev SA, Pike RN, Whisstock JC

Title:

X-ray crystal structure of MENT: evidence for functional loop-sheet polymers in chromatin condensation.

Journal:

EMBO J. 2006 Jul 12;25(13):3144-55. Epub 2006 Jun 29.

Abstract:

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.