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The symmetrical structure of structural maintenance of chromosomes (SMC) and MukB proteins: long, antiparallel coiled coils, folded at a flexible hinge.

Publication ,  Journal Article
Melby, TE; Ciampaglio, CN; Briscoe, G; Erickson, HP
Published in: J Cell Biol
September 21, 1998

Structural maintenance of chromosomes (SMC) proteins function in chromosome condensation and several other aspects of DNA processing. They are large proteins characterized by an NH2-terminal nucleotide triphosphate (NTP)-binding domain, two long segments of coiled coil separated by a hinge, and a COOH-terminal domain. Here, we have visualized by EM the SMC protein from Bacillus subtilis (BsSMC) and MukB from Escherichia coli, which we argue is a divergent SMC protein. Both BsSMC and MukB show two thin rods with globular domains at the ends emerging from the hinge. The hinge appears to be quite flexible: the arms can open up to 180 degrees, separating the terminal domains by 100 nm, or close to near 0 degrees, bringing the terminal globular domains together. A surprising observation is that the approximately 300-amino acid-long coiled coils are in an antiparallel arrangement. Known coiled coils are almost all parallel, and the longest antiparallel coiled coils known previously are 35-45 amino acids long. This antiparallel arrangement produces a symmetrical molecule with both an NH2- and a COOH-terminal domain at each end. The SMC molecule therefore has two complete and identical functional domains at the ends of the long arms. The bifunctional symmetry and a possible scissoring action at the hinge should provide unique biomechanical properties to the SMC proteins.

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Published In

J Cell Biol

DOI

ISSN

0021-9525

Publication Date

September 21, 1998

Volume

142

Issue

6

Start / End Page

1595 / 1604

Location

United States

Related Subject Headings

  • Protein Folding
  • Nuclear Proteins
  • Escherichia coli Proteins
  • Developmental Biology
  • Chromosomes, Bacterial
  • Chromosomal Proteins, Non-Histone
  • Bacterial Proteins
  • 32 Biomedical and clinical sciences
  • 31 Biological sciences
  • 11 Medical and Health Sciences
 

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Melby, T. E., Ciampaglio, C. N., Briscoe, G., & Erickson, H. P. (1998). The symmetrical structure of structural maintenance of chromosomes (SMC) and MukB proteins: long, antiparallel coiled coils, folded at a flexible hinge. J Cell Biol, 142(6), 1595–1604. https://doi.org/10.1083/jcb.142.6.1595
Melby, T. E., C. N. Ciampaglio, G. Briscoe, and H. P. Erickson. “The symmetrical structure of structural maintenance of chromosomes (SMC) and MukB proteins: long, antiparallel coiled coils, folded at a flexible hinge.J Cell Biol 142, no. 6 (September 21, 1998): 1595–1604. https://doi.org/10.1083/jcb.142.6.1595.
Melby, T. E., et al. “The symmetrical structure of structural maintenance of chromosomes (SMC) and MukB proteins: long, antiparallel coiled coils, folded at a flexible hinge.J Cell Biol, vol. 142, no. 6, Sept. 1998, pp. 1595–604. Pubmed, doi:10.1083/jcb.142.6.1595.

Published In

J Cell Biol

DOI

ISSN

0021-9525

Publication Date

September 21, 1998

Volume

142

Issue

6

Start / End Page

1595 / 1604

Location

United States

Related Subject Headings

  • Protein Folding
  • Nuclear Proteins
  • Escherichia coli Proteins
  • Developmental Biology
  • Chromosomes, Bacterial
  • Chromosomal Proteins, Non-Histone
  • Bacterial Proteins
  • 32 Biomedical and clinical sciences
  • 31 Biological sciences
  • 11 Medical and Health Sciences