Kowalczykowski Lab Home Page


Stephen Kowalczykowski, Distinguished Professor
University of California, Davis
Department of Microbiology and Molecular Genetics
of Molecular and Cellular Biology

Biochemistry, Molecular, Cellular and Developmental Biology, Biophysics, Genetics, and Microbiology Graduate Groups
Briggs Hall - Rm. 310
One Shields Ave
Davis, CA 95616-8665
(the next Napa... like living in Provence...)

E-MAIL:   sckowalczykowski@ucdavis.edu
PHONE (office):  53
0-752-5938      FAX (office):  530-752-5939

   PHONE (department):  530-752-2626   FAX (department):  530-752-9014
Focus in Chromosome Dynamics at U.C. Davis

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  Research Interests Publications People

Recent papers and papers in press

Our research interests include:


Molecular mechanism of genetic recombination
DNA strand exchange proteins
Homologous pairing

Recombination-intermediate structures
DNA helicases
DNA processing
Recombination hotspots


Biochemistry of DNA helicases
DNA unwinding and ATP hydrolysis
Translocation along DNA
Molecular motor mechanisms
Reconstituted in vitro reactions


Protein-nucleic acid interactions
Atomic force (scanning probe) microscopy
Single-molecule visualization
Equilibrium and kinetic properties
Fluorescence-based assays


[Click here to see a movie of translocation & unwinding by an individual RecBCD helicase along a single molecule of DNA]

  laser optical trap
Streptavidin-coated bead (1m)

More movies:
1 mM ATP
250 µM ATP #1
250 µM ATP #2
no ATP

News Flashes!

Liu, B., Baskin, R.J., and Kowalczykowski, S.C. (2013). DNA Unwinding heterogeneity by RecBCD results from static molecules able to equilibrate. Nature, 500, 482–485. (published online July 14, 2013 as doi: 10.1038/nature12333). PMID: 23851395; PMCID: PMC3779544.
[Abstract] [Full Text] [PDF] [ Supplementary Information]

(see EurekAlert.Org: Biochemists uphold law of physics [Video] [PDF])
(see Futurity: DNA enzyme's speed confirms physics law [PDF])

(see Phys.Org: Biochemists uphold law of physics (w/ video) [Video] [PDF])
(see ScienceDaily: Biochemists uphold load of physics [PDF])

(see UC Davis News and Information Biochemists uphold law of physics (WITH VIDEO) [Video] [Printable])

Paeschke, K., Bochman, M.L., Garcia, P.D., Cejka, P., Friedman, K.L., Kowalczykowski, S.C., and Zakian, V.A. (2013). Pif1 family helicases suppress genome instability at G-quadruplex motifs. Nature, 497, 458-62 (published online May 8, 2013 as doi: 10.1038/nature12149).  PMID: 23657261; PMCID: PMC3680789.
 [Abstract] [Full Text] [PDF] [Supplementary Information]
(see Innovations Report: Stability for the genome [PDF])
(see Nature New & Views: DNA replication: Driving past four-stranded snags  [PDF])
(see NSF Science360 New Service  [Full Text] [PDF])
(see Universität Würzburg
: Stability for the genome [PDF])

Cannavo, E., Cejka, P., and Kowalczykowski, S.C. (2013). Relationship of DNA degradation by Saccharomyces cerevisiae Exonuclease 1 and its stimulation by RPA and Mre11-Rad50-Xrs2 to DNA end resection. Proc. Natl. Acad. Sci. U.S.A., 109 (published online April 15, 2013 as doi: 10.1073/pnas.1305166110).  PMID: 23589858; PMCID: PMC3645542.
[Abstract] [Full Text] [PDF] [Supporting Information]

Jensen, R.B., Ozes, A., Kim, T., Estep, A., and Kowalczykowski, S.C. (2013). BRCA2 is epistatic to the RAD51 paralogs in response to DNA damage. DNA Repair 12, 306-311. PMID: 23384538; PMCID: PMC3602134.
[Abstract] [Full Text] [PDF] [Supplementary Figure I] [Supplementary Figure II] [Supplementary Figure III]
Access the recommendation on F1000Prime

Forget, A.L., Dombrowski, C.C., Amitani, I., and Kowalczykowski, S.C. (2013). Exploring protein-DNA interactions in 3D using in situ construction, manipulation, and visualization of individual DNA-dumbbells with optical traps, microfluidics, and fluorescence microscopy. Nature Protocols, 8, 525-538. PMID: 23411634.
[Abstract] [Full Text] [PDF] [Supplementary Figure 1]

Bell, J.C., Plank, J.L., Dombrowski, C.C., and Kowalczykowski, S.C. (2012). Direct imaging of RecA nucleation and growth on single molecules of SSB-coated ssDNA. Nature, 491, 274-278 (published online 24 October 2012 as doi: 10.1038/nature11598). PMID: 23103864.
[Abstract] [Full Text] [PDF] [Supplementary Information] [Video 1: Direct imaging of nucleation and growth of RecA on SSB-coated ssDNA] [Video 2: Optical trapping and manipulation of single molecules of gapped DNA for direct imaging of RecAf filament assembly]
(see Nature News & Views: A glimpse of molecular competition [PDF])
(see Phys.org News: Single-DNA images give clues to breast cancer [PDF])
(see Scientific Blogging: Rad51: Watching single strands of DNA being prepped for repair could help fight breast cancer  [Printable] [PDF])
(see UC Davis News and Information: Single-DNA images give clues to breast cancer  [Video] [PDF])
Access the recommendation on F1000Prime

Morimatsu, K., Wu, Y., and Kowalczykowski, S.C. (2012).  RecFOR proteins target RecA protein to a DNA gap with either DNA or RNA at the 5'-terminus: Implication for repair of stalled replication forks. J. Biol. Chem. 287, 35621-35630 (published online 17 August 2012 as 10.1074/jbc.M112.397034). PMID: 22902627; PMCID: PMC3471720.
[Abstract] [Full Text] [PDF] [Supplemental Information]

Cejka, P., Plank, J.L., Dombrowski, C.C., and Kowalczykowski, S.C. (2012). Decatenation of DNA by the S. cerevisiae Sgs1–Top3–Rmi1 and RPA complex: A mechanism for disentangling chromosomes. Mol. Cell, 47, 886-896 (published online August 15, 2012). PMID: 22885009; PMCID: PMC3462259.
[Abstract] [Full Text] [PDF] [Supplemental Information]
Access the recommendation on F1000Prime

View my collection, "My Bibliography" from NCBI


Scott, Eugenie C., ... Kowalczykowski, S.C., et al. 2004. The Morphology of Steve. Annals of Improbable Research, July/August, 4, pp. 24-29.
[PDF] [Project Steve] [FAQ] [Ten Years of Project Steve]