Donald L. Court, Ph.D.

Donald L. Court, Ph.D.

  • Center for Cancer Research
  • National Cancer Institute
RNA Biology Laboratory


Dr. Court developed recombineering as a revolutionary way to engineer DNA in living cells and has defined its mechanism; discovered several gene regulatory mechanisms that describe the systems biology of phage λ and Escherichia coli (E. coli); defined structures and action mechanisms for the DICER homolog RNaseIII, and identified the Era-GTPase as a cell-cycle check-point regulator in E. coli that is present from bacteria to mammals.

Areas of Expertise

Bacterial And Phage Genetics
Transcriptional Regulation
Post-transcriptional Regulation
DNA Recombination
Ribosomal RNA Transcription And Maturation


Selected Publications

Examining a DNA Replication Requirement for Bacteriophage λ Red- and Rac Prophage RecET-Promoted Recombination in Escherichia coli

Thomason LC, Costantino N, Court DL.
mBio. 7(5): e01443-16, 2016. [ Journal Article ]

tCRISPRi: tunable and reversible, one-step control of gene expression

Li XT, Jun Y, Erickstad MJ, Brown SD, Parks A, Court DL, Jun S.
Sci Rep. 6: 39076, 2016. [ Journal Article ]

Location of the unique integration site on an Escherichia coli chromosome by bacteriophage lambda DNA in vivo

Tal A, Arbel-Goren R, Costantino N, Court DL, Stavans J.
Proc Natl Acad Sci USA. 111: 7308-12, 2014. [ Journal Article ]

Bacteriophage λ N protein inhibits transcription slippage by Escherichia coli RNA polymerase

Parks AR, Court C, Lubkowska L, Jin DJ, Kashlev M, Court DL.
Nucleic Acids Res. 42(9): 5823-5829, 2014. [ Journal Article ]

Bacterial DNA polymerases participate in oligonucleotide recombination

Li X, Thomason LC, Sawitzke JA, Costantino N, Court DL
Mol Microbiol. 88(5): 906-20, 2013. [ Journal Article ]


Journal of Bacteriology cover Nov 2020

Overproduction of a Dominant Mutant of the Conserved Era GTPase Inhibits Cell Division in Escherichia coli

Published Date

Cell growth and division are coordinated, ensuring homeostasis under any given growth condition, with division occurring as cell mass doubles. The signals and controlling circuit(s) between growth and division are not well understood; however, it is known in Escherichia coli that the essential GTPase Era, which is growth rate regulated, coordinates the two functions and may be a checkpoint regulator of both. We have isolated a mutant of Era that separates its effect on growth and division. When overproduced, the mutant protein Era647 is dominant to wild-type Era and blocks division, causing cells to filament. Multicopy suppressors that prevent the filamentation phenotype of Era647 either increase the expression of FtsZ or decrease the expression of the Era647 protein. Excess Era647 induces complete delocalization of Z rings, providing an explanation for why Era647 induces filamentation, but this effect is probably not due to direct interaction between Era647 and FtsZ. The hypermorphic ftsZ* allele at the native locus can suppress the effects of Era647 overproduction, indicating that extra FtsZ is not required for the suppression, but another hypermorphic allele that accelerates cell division through periplasmic signaling, ftsL*, cannot. Together, these results suggest that Era647 blocks cell division by destabilizing the Z ring.


Xiaomei Zhou, Howard K. Peters III, Xintian Li, Nina Costantino, Vandana Kumari, Genbin Shi, Chao Tu, Todd A. Cameron, Daniel P. Haeusser, Daniel E. Vega, Xinhua Ji, William Margolin, Donald L. Court See related article in Journal of Bacteriology November 2020, vol. 202, no. 21, e00342-20.

cover of Structure Dec 2001

Crystallographic and Modeling Studies of RNase III Suggest a Mechanism for Double-Stranded RNA Cleavage

Published Date

Background: Ribonuclease III belongs to the family of Mg2+-dependent endonucleases that show specificity for double-stranded RNA (dsRNA). RNase III is conserved in all known bacteria and eukaryotes and has 1–2 copies of a 9-residue consensus sequence, known as the RNase III signature motif. The bacterial RNase III proteins are the simplest, consisting of two domains: an N-terminal endonuclease domain, followed by a double-stranded RNA binding domain (dsRBD). The three-dimensional structure of the dsRBD in Escherichia coli RNase III has been elucidated; no structural information is available for the endonuclease domain of any RNase III.

Results: We present the crystal structures of the RNase III endonuclease domain in its ligand-free form and in complex with Mn2+. The structures reveal a novel protein fold and suggest a mechanism for dsRNA cleavage. On the basis of structural, genetic, and biological data, we have constructed a hypothetical model of RNase III in complex with dsRNA and Mg2+ ion, which provides the first glimpse of RNase III in action.

Conclusions: The functional RNase III dimer is formed via mainly hydrophobic interactions, including a “ball-and-socket” junction that ensures accurate alignment of the two monomers. The fold of the polypeptide chain and its dimerization create a valley with two compound active centers at each end of the valley. The valley can accommodate a dsRNA substrate. Mn2+ binding has significant impact on crystal packing, intermolecular interactions, thermal stability, and the formation of two RNA-cutting sites within each compound active center.


Blaszczyk J, Tropea JE, Bubunenko M, Routzahn KM, Waugh DS, Court DL, Ji X. Structure. 2001 Dec;9(12):1225-36. PMID:1173804