Post-translational modification and calcium binding are key pre-requisites for centrosome duplication andseparation. These processes are regulated in healthy tissues and are defective in disease states such ascancer. Abnormalities, such as amplified and multiple centrosomes, are often observed in human breast,colorectal, and other cancers.Centrin is an EF-hand protein that plays both structural and regulatory roles in the centrosome. Thiscalcium-binding protein interacts at low calcium levels with a novel 1242-amino acid protein known as Sfi1,which contains up to 23 centrin-binding sites. Coupled biophysical, structural, and dynamic analyses ofthe centrin/SfM complex are essential to the understanding of its biological function.
In Aim I, we will determine the interactions involved in the formation of the centrin-Sfil complex andobserve how they change during the dynamic contraction and elongation of Sfi1. Our experiments willaddress key questions underlying the molecular basis of this complex interaction. We will study the processesof calcium-binding and phosphorylation in centrin and relate them to the structural changes that triggercontraction and elongation in Sfi1.
In Aim 2, we will determine the structure of Sfi1 and measure the kineticsof its contraction and elongation. We expect that structural characterizations of Sfi1 will yield insight into thestructure-function relationship of this protein.Our results will elucidate how newly duplicated centrosomes separate and migrate to opposite sides ofthe nucleus. With the completion of the proposed project, we expect to attain our short-term goal ofdescribing at the molecular level the conformational changes that occur in centrin and Sfi1 upon complexformation. We hope to define the molecular mechanism of Sfi1 contraction and the conditions that facilitatethis event. In addition, characterization of the phosphorylated form of centrin will contribute greatly tostructural knowledge of this post-translational modification, since few phosphorylated proteins have beenstructurally resolved to date.The significance of these results lies in our understanding of the regulatory and structural aspects of celldivision at the centrosome level. Our findings will provide essential information on the mechanisms by whichcentrosomal proteins function and help define their biological activities.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Minority Biomedical Research Support - MBRS (S06)
Project #
2S06GM008103-34
Application #
7284623
Study Section
Minority Programs Review Committee (MPRC)
Project Start
2007-05-01
Project End
2011-04-30
Budget Start
2007-05-01
Budget End
2008-04-30
Support Year
34
Fiscal Year
2007
Total Cost
$372,784
Indirect Cost
Name
University of Puerto Rico Mayaguez
Department
Type
DUNS #
175303262
City
Mayaguez
State
PR
Country
United States
Zip Code
00681
Díaz Casas, Adalberto; Chazin, Walter J; Pastrana-Ríos, Belinda (2017) Prp40 Homolog A Is a Novel Centrin Target. Biophys J 112:2529-2539
Lara Rodriguez, L; Sundaram, P A (2016) Corrosion behavior of plasma electrolytically oxidized gamma titanium aluminide alloy in simulated body fluid. Mater Chem Phys 181:67-77
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Pastrana-Rios, Belinda; Del Valle Sosa, Liliana; Santiago, Jorge (2015) Trifluoroacetic acid as excipient destabilizes melittin causing the selective aggregation of melittin within the centrin-melittin-trifluoroacetic acid complex. Struct Dyn 2:041711
Santiago-Medina, P; Sundaram, P A; Diffoot-Carlo, N (2015) Titanium Oxide: A Bioactive Factor in Osteoblast Differentiation. Int J Dent 2015:357653
Santiago-Medina, Pricilla; Sundaram, Paul A; Diffoot-Carlo, Nanette (2014) The effects of micro arc oxidation of gamma titanium aluminide surfaces on osteoblast adhesion and differentiation. J Mater Sci Mater Med 25:1577-87
Vera, José L; Rullán, Jorge; Santos, Natasha et al. (2014) Functionalized ferrocenes: The role of the para substituent on the phenoxy pendant group. J Organomet Chem 749:204-214
Lara Rodriguez, L; Sundaram, P A; Rosim-Fachini, E et al. (2014) Plasma electrolytic oxidation coatings on ?TiAl alloy for potential biomedical applications. J Biomed Mater Res B Appl Biomater 102:988-1001
Dominguez-Garcia, Moralba; Ortega-Zuniga, Carlos; Melendez, Enrique (2013) New tungstenocenes containing 3-hydroxy-4-pyrone ligands: antiproliferative activity on HT-29 and MCF-7 cell lines and binding to human serum albumin studied by fluorescence spectroscopy and molecular modeling methods. J Biol Inorg Chem 18:195-209
Pastrana-Rios, Belinda; Reyes, Myrna; De Orbeta, Jessica et al. (2013) Relative stability of human centrins and its relationship to calcium binding. Biochemistry 52:1236-48

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