Díaz Casas, Adalberto

Profile Picture

Filters

2012 - 20182
Reset filters

Settings

Citations

Publication Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    PublicationRestricted
    Thermodynamics governing binding of Homo sapiens centrin – Homo sapiens Sfi1p21 Complexes
    (2012) Díaz Casas, Adalberto; Pastrana Ríos, Belinda; College of Arts and Sciences - Sciences; Meléndez Martínez, Enrique; Ríos Guillet, Robert; Department of Chemistry; Sundaram, Paul A.
    Centrin is a member of the EF-hand superfamily of calcium-binding proteins and has a molecular weight of ~20 kDa. In Homo sapiens, four centrin isoforms have been determined: centrin 1 (Hscen1), which is found in male germ cells, certain neurons and ciliated cells, centrin 2 (Hscen2) and centrin 3 (Hscen3) are expressed in all somatic cells, and centrin 4 (Hscen4) found in neurons. We focused our research on Sfi1, a centrin binding protein of 1242 amino acids and comprising 23 tandem centrin-binding sites (CBS). Specifically, we studied a soluble Sfi1 peptide comprised of the 21st centrin binding site (HsSfi1p21). HsSfi1p21 exhibits the hydrophobic triad (W1L4L8) which is found to be essential for the interaction between centrin and its biological targets. Using isothermal titration calorimetry, the interaction between Hscen1 and HsSfi1p21 was analyzed at 25°C, 30°C, 35°C, and 40°C. At 35°C, the complex shows the highest stability (ΔG = -10.2 kcal/mol) and affinity (Ka = 1.7 x 107 M -1 ) with a favorable enthalpy (ΔH = -29.0 kcal/mol) and unfavorable entropy (-TΔS = 18.8 kcal/mol). By a comparative thermodynamic analysis of the interaction of three human centrin isoforms (Hscen1, Hscen2, and Hscen3) with HsSfi1 at 30°C, we found that Hscen3-HsSfi1p21 complex presented the highest stability and affinity interaction. From these results, we found that the stability on centrin-Sfi1p complex is dependent to the relative stability of centrin.
  • Thumbnail Image
    PublicationRestricted
    Prp40: A novel centrin-binding protein
    (2018) Díaz Casas, Adalberto; Pastrana Ríos, Belinda; College of Arts and Sciences - Sciences; Meléndez Martínez, Enrique; Ríos Guillet, Robert; Department of Chemistry; Plaza Delestre, María de L.
    Pre-mRNA processing protein 40 (Prp40) is a modular protein that has an essential role in the initiation step of pre-mRNA splicing. In Homo sapiens, Prp40 has two putative homologs: Prp40 homolog A (HsPrp40A) and homolog B (HsPrp40B). This splicing factor comprises two WW domains and six tandem FF domains. In addition, Prp40 has two leucine-rich nuclear export signals, but little is known about the function of Prp40 in the export process. Centrin, a calcium-binding protein that is known to have a role in mRNA and protein export, is one of the 350 “eukaryotic signature proteins.” We identified a centrin-binding site that is located within the third FF (FF3) domain of HsPrp40A. This centrin-binding site is highly similar to the first nuclear export signal consensus sequence identified in yeast Prp40. We confirmed the interaction between a HsPrp40A synthetic peptide (HsPrp40Ap) and centrin, using isothermal titration calorimetry and two-dimensional infrared (2D IR) correlation spectroscopy. In addition, spectroscopic and thermodynamic studies carried out on HsPrp40A’s full FF3 domain provided new insights about the stability of this domain. Finally, we proceeded to study the molecular behavior of HsPrp40A’s FF3 domain under thermal stress, using differential scanning calorimetry, circular dichroism, and 2D IR correlation spectroscopies. The comprehensive body of evidence supports a novel centrin target with potential regulatory functions within the nucleus, the scientific implications being that the centrin-Prp40A complex has a functional role in pre-mRNA splicing.