Format

Send to

Choose Destination
Chromosome Res. 2016 Sep;24(3):339-53. doi: 10.1007/s10577-016-9528-6. Epub 2016 May 5.

Dependence of the structure and mechanics of metaphase chromosomes on oxidized cysteines.

Author information

1
Department of Molecular Biosciences, Northwestern University, Evanston, IL, 60208, USA.
2
Department of Physics and Astronomy, Northwestern University, Evanston, IL, 60208, USA.
3
Proteomics Core, Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, 60208, USA.
4
Department of Molecular Biosciences, Northwestern University, Evanston, IL, 60208, USA. john-marko@northwestern.edu.
5
Department of Physics and Astronomy, Northwestern University, Evanston, IL, 60208, USA. john-marko@northwestern.edu.

Abstract

We have found that reagents that reduce oxidized cysteines lead to destabilization of metaphase chromosome folding, suggesting that chemically linked cysteine residues may play a structural role in mitotic chromosome organization, in accord with classical studies by Dounce et al. (J Theor Biol 42:275-285, 1973) and Sumner (J Cell Sci 70:177-188, 1984a). Human chromosomes isolated into buffer unfold when exposed to dithiothreitol (DTT) or tris(2-carboxyethyl)phosphine (TCEP). In micromanipulation experiments which allow us to examine the mechanics of individual metaphase chromosomes, we have found that the gel-like elastic stiffness of native metaphase chromosomes is dramatically suppressed by DTT and TCEP, even before the chromosomes become appreciably unfolded. We also report protein labeling experiments on human metaphase chromosomes which allow us to tag oxidized and reduction-sensitive cysteine residues. PAGE analysis using fluorescent labels shows a small number of labeled bands. Mass spectrometry analysis of similarly labeled proteins provides a list of candidates for proteins with oxidized cysteines involved in chromosome organization, notably including components of condensin I, cohesin, the nucleosome-interacting proteins RCC1 and RCC2, as well as the RNA/DNA-binding protein NONO/p54NRB.

KEYWORDS:

Chromosome structure; Cysteine; Disulfide; Metaphase chromosome

PMID:
27145786
PMCID:
PMC4970972
DOI:
10.1007/s10577-016-9528-6
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Springer Icon for PubMed Central
Loading ...
Support Center