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Teresa Corona

Publications and source records attributed to Teresa Corona.

5 recordsLinked to original sources
PubMed2003

Activation of site-specific DNA integration in human cells by a single chain integration host factor.

The heterodimeric integration host factor (IHF) is a site-specific DNA-binding and DNA-bending protein from Escherichia coli. It plays essential roles in a variety of DNA transactions including recombination, transcription and DNA replication. IHF's ability for concerted binding and bending of DNA is key to its biological function. Here we report the design, characterization and application of a single polypeptide chain IHF, termed scIHF2. In a novel approach for protein engineering, we inserted almost the entire alpha-subunit of IHF into the beta-subunit. DNA binding and DNA bending assays revealed that purified wild-type IHF and scIHF2 behave very similarly. Further, scIHF2 is required for site-specific integrative recombination by phage lambda integrase and for pSC101 replication in a DeltaIHF E.coli host. It also triggers site-specific integrative and excisive recombination in vitro to the same extent as the wild-type protein. We also demonstrate that scIHF2 is stably expressed in HeLa cells, that it is localized primarily in the cell nucleus and that it triggers integrative recombination in mammalian cells by wild-type integrase. Hence, scIHF2 may be used as a novel regulatory cofactor for recombination or other DNA transactions in mammalian cells that require or benefit from sequence-specific high precision DNA bending.

Amino Acid Sequence↗
PubMed2002

Site-specific recombination in eukaryotic cells mediated by mutant lambda integrases: implications for synaptic complex formation and the reactivity of episomal DNA segments.

Mutant lambda integrases catalyze site-specific DNA recombination in the absence of accessory factors IHF, XIS, and negative DNA supercoiling. Here we investigate the effects that a human cellular environment exerts on these reactions in order to (i) gain further insights into mechanistic aspects of recombination in eukaryotic cells and (ii) to further develop the Int system for biotechnological applications. First, we compared intra- and intermolecular integrative as well as excisive recombination pathways on episomal substrates after co-transfection with recombinase expression vectors. Our results demonstrate that, within 24 hours after transfection, intermolecular recombination by mutant integrase is at least as efficient as intramolecular recombination. Second, a significant intermolecular recombination activity was observed between two copies of a recombination site containing only the 21 bp comprising core-type DNA sequence. This basic activity was stimulated several-fold when arm-type DNA sequences were present in addition to core sites. Therefore, one recombination pathway in human cells involves mutant integrases bound solely at core sites, which is reminiscent of the Flp/FRT and Cre/loxP pathways. The stimulatory effect of arm-type sequences could be explained by an increase in integrase concentration in the vicinity of core sites. We show, in addition, that an N-terminal truncated mutant integrase exhibited only a very weak recombinogenic activity in a eukaryotic background. This result strengthens a functional role for the N-terminal domain in recombination in addition to its arm-type DNA-binding activity. Finally, we demonstrate that low level integrative recombination by wild-type integrase is stimulated when purified integration host factor is co-transfected. This corroborates our previous conclusion that sufficient amounts of eukaryotic protein co-factors, which could functionally replace IHF, are not present in human cells. It also provides a potential means to control site-specific recombination in eukaryotic cells.

Attachment Sites, Microbiological↗
PubMedDate not supplied

[Excessive daytime sleepiness in Mexico city].

OBJECTIVE: To determine the prevalence of excessive daytime somnolence (EDS) in a sample of residents from Mexico City. METHODS: A cross-sectional survey was done using a randomized telephone survey. A structured questionnaire (including demographic and clinical data) and Epworth Sleepiness Scale, a valid and reliable instrument for the detection of EDS, were administered. RESULTS: A total sample of 200 subjects was obtained, with a mean age of 37 +/- 16.24 years. EDS was found in 31.5% of the subjects; 12.5% considered that EDS interfered in a significant way with daily activities, and 9% with work related abilities. Subjects with EDS were older, came from lower socio-economic status, and had a significantly higher body mass index. DISCUSSION: Our results indicate that EDS is more frequent in Mexico City residents than in other populations. Notwithstanding, the association between EDS with advanced age, lower socio-economic status and high body mass index requires further investigation.

Adult↗