Structural Maintenance of Chromosomes Protein C-terminal Domains Bind Preferentially to DNA with Secondary Structure*
- Alexandre T. Akhmedov,
- Christian Frei‡,
- Monika Tsai-Pflugfelder‡,
- Börries Kemper§,
- Susan M. Gasserঠand
- Rolf Jessberger‖
- From the Basel Institute for Immunology, Grenzacherstrasse 487, CH-4005 Basel, Switzerland, ‡ISREC, Chemin des Boveresses 155, CH-1066 Epalinges/Lausanne, Switzerland, and the§Institute for Genetics, University of Cologne, Zülpicher Strasse 47, D-50674 Cologne, Germany
Abstract
Structural maintenance of chromosomes (SMC) proteins interact with DNA in chromosome condensation, sister chromatid cohesion, DNA recombination, and gene dosage compensation. How individual SMC proteins and their functional domains bind DNA has not been described. We demonstrate the ability of the C-terminal domains ofSaccharomyces cerevisiae SMC1 and SMC2 proteins, representing two major subfamilies with different functions, to bind DNA in an ATP-independent manner. Three levels of DNA binding specificity were observed: 1) a >100-fold preference for double-stranded versus single-stranded DNA; 2) a high affinity for DNA fragments able to form secondary structures and for synthetic cruciform DNA molecules; and 3) a strong preference for AT-rich DNA fragments of particular types. These include fragments from the scaffold-associated regions, and an alternating poly(dA-dT)-poly(dT-dA) synthetic polymer, as opposed to a variety of other polymers. Reannealing of complementary DNA strands is also promoted primarily by the C-terminal domains. Consistent with theirin vitro DNA binding activity, we show that overexpression of the SMC C termini increases plasmid loss without altering viability or cell cycle progression.
Footnotes
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↵* The Basel Institute for Immunology was founded and is supported by Hoffman-LaRoche Inc., Basel, Switzerland.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵¶ Supported by ISREC, the Swiss National Science Foundation, the Human Frontiers Science Program, and the Swiss Cancer League.
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↵‖ To whom correspondence should be addressed. Tel.: 41-61-605-1284; Fax: 41-61-605-1364; E-mail: jessberger{at}bii.ch.
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↵2 C. Frei, unpublished results.
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↵3 R. Jessberger, submitted for publication.
- Abbreviations:
- SMC
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structural maintenance of chromosomes
- SAR
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scaffold-associated region
- bp
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base pair(s)
- CEN
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centromere
- GST
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glutathione S-transferase
- ss
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single-stranded
- ds
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double-stranded.
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- Received May 6, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
