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.com
Volume 10, Issue 8 (Suppl)
J Proteomics Bioinform, an open access journal
ISSN: 0974-276X
Structural Biology 2017
September 18-20, 2017
9
th
International Conference on
Structural Biology
September 18-20, 2017 Zurich, Switzerland
Alessandra Astegno, J Proteomics Bioinform 2017, 10:8(Suppl)
DOI: 10.4172/0974-276X-C1-0100
A biophysical and structural approach to investigate calcium sensor properties of plant calmodulin-
like proteins
Alessandra Astegno
University of Verona, Italy
C
alcium is an essential second messenger in plants that regulates various signaling pathways through stimulus-specific
Ca
2+
signatures, which are decoded and converted into a wide variety of biochemical changes by Ca
2+
sensors. Besides
evolutionarily conserved calmodulin (CaM), plants exclusively possess a group of calmodulin-like proteins (CMLs), which
play central roles in the coordination of plant responses to different external stimuli. Nevertheless, only few of these proteins
have been thoroughly characterized and demonstrated to function as Ca
2+
sensors. Our research is focused on the investigation
of the metal-binding, physicochemical and structural properties of various plant CMLs using complementary biophysical and
structural approaches to correlate their properties with the biological activity. We have recently characterized CML36 from
Arabidopsis thaliana
, demonstrating that
in vitro
the protein shows feature consistent with Ca
2+
sensor function. ITC analysis
revealed that CML36 possesses two high affinity Ca
2+
/Mg
2+
mixed sites and two low affinity Ca
2+
-specific sites. Binding of Ca
2+
to CML36 increases its α-helical content and triggers a conformational change that exposes hydrophobic surfaces necessary
for target recognition. Ca
2+
and Mg
2+
ions also stabilized the tertiary structure of CML36. Cations binding to the Ca
2+
/Mg
2+
mixed sites appear to guide a large structural transition from a loosely packed molten globule apo-state to a well-defined, stable
holo-structure. Through
in vitro
binding experiments, we showed that CML36 directly interacts with the N-terminal domain
of
Arabidopsis
Ca
2+
-ATPase isoform 8 (ACA8), a type IIB Ca
2+
pump localized at the plasma membrane (PM). Moreover, we
demonstrated that this interaction promotes ACA8 Ca
2+
-dependent hydrolytic activity
in vitro
.
Biography
Alessandra Astegno is interested in various aspects of Protein Chemistry, including folding, Evolution and structure-function relationship of proteins and
Macromolecular assemblies. She obtained a PhD in Applied Biotechnologies from University of Verona in 2010. She is currently working as an Assistant Professor
in Biochemistry at the Department of Biotechnology of the University of Verona. She has a solid background in recombinant protein expression and purification,
functional and structural characterization of metallo-proteins as well as PLP-dependent enzymes. Recently, her work focused on the study of calcium signaling
in higher plants through biophysical, biochemical and structural characterization of calcium sensor proteins, such as calmodulin and calmodulin like proteins of
Arabidopsis thaliana.
alessandra.astegno@univr.it