Biomedical subjects

T E Cloutier

Publications and source records attributed to T E Cloutier.

3 recordsLinked to original sources

PubMed2005

DNA twisting flexibility and the formation of sharply looped protein-DNA complexes.

Gene-regulatory complexes often require that pairs of DNA-bound proteins interact by looping-out short (often approximately 100-bp) stretches of DNA. The loops can vary in detailed length and sequence and, thus, in total helical twist, which radically alters their geometry. How this variability is accommodated structurally is not known. Here we show that the inherent twistability of 89- to 105-bp DNA circles exceeds theoretical expectation by up to 400-fold. These results can be explained only by greatly enhanced DNA flexibility, not by permanent bends. They invalidate the use of classic theories of flexibility for understanding sharp DNA looping but support predictions of two recent theories. Our findings imply an active role for DNA flexibility in loop formation and suggest that variability in the detailed helical twist of regulatory loops is accommodated naturally by the inherent twistability of the DNA.

DNA↗

PubMed2001

Kinetic trapping of DNA by transcription factor IIIB.

High levels of RNA polymerase III gene transcription are achieved by facilitated recycling of the polymerase on transcription factor IIIB (TFIIIB)-DNA complexes that are stable through multiple rounds of initiation. TFIIIB-DNA complexes in yeast comprise the TATA-binding protein (TBP), the TFIIB-related factor TFIIIB70, and TFIIIB90. The high stability of the TFIIIB-DNA complex is conferred by TFIIIB90 binding to TFIIIB70-TBP-DNA complexes. This stability is thought to result from compound bends introduced in the DNA by TBP and TFIIIB90 and by protein-protein interactions that obstruct DNA dissociation. Here we present biochemical evidence that the high stability of TFIIIB-DNA complexes results from kinetic trapping of the DNA. Thermodynamic analysis shows that the free energies of formation of TFIIIB70-TBP-DNA (DeltaG degrees = -12.10 +/- 0.12 kcal/mol) and TFIIIB-DNA (DeltaG degrees = -11.90 +/- 0.14 kcal/mol) complexes are equivalent whereas a kinetic analysis shows that the half-lives of these complexes (46 +/- 3 min and 95 +/- 6 min, respectively) differ significantly. The differential stability of these isoenergetic complexes demonstrates that TFIIIB90 binding energy is used to drive conformational changes and increase the barrier to complex dissociation.

DNA↗

PubMed1999

PAX3 gene structure, alternative splicing and evolution.

PAX3 is a member of the paired box family of transcription factors that function during embryogenesis and cancer epigenesis. Mutations in PAX3 cause Waardenburg syndrome (types 1 and 3), Craniofacial-deafness-hand syndrome and alveolar rhabdomyosarcoma in humans and the Splotch phenotype in mice. In this study, we describe the genomic structure of PAX3, including novel coding sequences and the complete 3' UTR. Alternative transcripts of PAX3 were identified in various tissues, including human adult skeletal muscle and mouse embryos. One of the novel alternative transcripts is evolutionarily conserved in quail and can transactivate a reporter construct containing the mouse c-met promoter. The sequences and alternative transcripts reported herein extend our understanding of the function and evolution of PAX3 in vertebrates and enable a comprehensive mutation screen for individuals with Waardenburg syndrome.

Adult↗