Navigation Links
Single-molecule technique captures calcium sensor calmodulin in action
Date:8/14/2009

It's well known that the protein calmodulin specifically targets and steers the activities of hundreds of other proteins mostly kinases in our cells, thus playing a role in physiologically important processes ranging from gene transcription to nerve growth and muscle contraction But just how it distinguishes between target proteins is not well understood. Methods developed by biophysicists at the Technische Universitaet Muenchen (TUM) have enabled them to manipulate and observe calmodulin in action, on the single-molecule scale. In recent experiments, as they report in the early edition of PNAS, the Proceedings of the National Academy of Sciences, they compared the sequences of structural and kinetic changes involved in binding two different kinases. The results reveal new details of how calmodulin binds and regulates its target proteins.

A so-called signaling protein and "calcium sensor," calmodulin gives start and stop signals for a great number of intracellular activities by binding and releasing other proteins. Calmodulin can bind up to four calcium ions, and the three-dimensional spatial structure of calmodulin varies with the number of calcium ions bound to it. This structure in turn helps to determine which amino acid chains peptides and proteins the calmodulin will bind.

Techniques such as X-ray structural analysis offer snapshots, at best, of steps in this intracellular work flow. But single-molecule atomic-force spectroscopy has opened a new window on such dynamic processes.

Professor Matthias Rief and colleagues at the Technische Universitaet Muenchen had previously shown that they could fix a single calmodulin molecule between a surface and the cantilever tip of a specially built atomic-force microscope, expose it to calcium ions in solution, induce peptide binding and unbinding, and measure changes in the molecule's mechanical properties as it did its work.

"What is special about our technique," Rief says, "is that we can work directly in aqueous solution. We can make our measurements in exactly the conditions under which the protein works in its natural environment. So we can directly observe how the calmodulin snatches the amino acid chain and folds itself, to hold its target fast." Measuring the force needed to bend the calmodulin molecule out of its stable condition at any given moment enables the researchers to compute the energies associated with binding both the calcium ions and the amino acid chains. And by following changes in the molecule's mechanical properties over time, they also can determine how long a protein fragment remains bound.

The results Rief and biophysicist Jan Philipp Junker report in the early edition of PNAS show that their approach also enables detailed comparative studies of binding sequences for different target proteins. The target sequences observed in these experiments are called skMLCK and CaMKK. Rief and Junker used mechanical force actually pulling on complexes of calmodulin and the target peptides at rates of 1 nanometer per second or less to slow down the processes to observable time scales and to clearly separate the individual unbinding steps.

"By applying mechanical force," Junker says, "we are able to dismantle the calmodulin-target peptide complex with surgical precision. Using conventional methods, this would be very difficult to do."

Among the detailed insights this approach made accessible are the hierarchy of folding and target binding, the sequence of unbinding events, and target-specific differences in terms of what is called cooperative binding.


'/>"/>

Contact: Patrick Regan
regan@zv.tum.de
49-892-892-2743
Technische Universitaet Muenchen
Source:Eurekalert  

Related biology technology :

1. BioNanomatrix Awarded New NIH Grant for Development of Nanoscale Platform for Single-Molecule DNA Mapping and Haplotype Applications
2. Model for the assembly of advanced, single-molecule-based electronic components developed at Pitt
3. New MRI technique could mean fewer breast biopsies in high-risk women
4. New statistical technique improves precision of nanotechnology data
5. Five Cord Blood Transplant Centers in Catalonia and Valencia Join a Study to Test a New Technique to Treat Leukemia and Lymphoma
6. Secret of sandcastle construction could help revive ancient building technique, researchers say
7. Quest Diagnostics to Present Genomic Studies Related to New Testing Techniques for Leukemia and Prostate Cancer at 2009 ASCO Meeting
8. Gender-Selection Technique Embraced for Hopeful Parents
9. Novel CU-Boulder technique shrinks size of nanotechnology circuitry
10. Hebrew University scientist develop technique for eliminating reblockage of arteries
11. New imaging technique reveals the atomic structure of nanocrystals
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Single-molecule technique captures calcium sensor calmodulin in action
(Date:10/11/2017)... LAGUNA HILLS, Calif. , Oct. 11, 2017 /PRNewswire/ ... London (ICR) and University of ... tool to risk-stratify patients with multiple myeloma (MM), in a ... . The University of Leeds is ... Myeloma UK, and ICR will perform the testing services to ...
(Date:10/10/2017)... , ... October 10, 2017 ... ... cancer-focused pharmaceutical company advancing targeted antibody-drug conjugate (ADC) therapeutics, today confirmed licensing ... HPLN (Hybrid Polymerized Liposomal Nanoparticle), a technology developed in collaboration with Children’s ...
(Date:10/10/2017)... ... October 10, 2017 , ... USDM ... firm for the life sciences and healthcare industries, announces a presentation by Subbu ... , The presentation, “Automating GxP Validation for Agile Cloud Platforms,” will present a ...
(Date:10/9/2017)... ... 09, 2017 , ... The Giving Tree Wellness Center announces ... needs of consumers who are incorporating medical marijuana into their wellness and health ... As operators of two successful Valley dispensaries, The Giving Tree’s two founders, Lilach ...
Breaking Biology Technology:
(Date:8/15/2017)... 15 2017   ivWatch LLC , a medical device company ... today announced receipt of its ISO 13485 Certification, the global standard ... Organization for Standardization (ISO®). ... Model 400 Continuous Monitoring device for the early detection of IV ... "This is an important milestone for ...
(Date:6/23/2017)... ARMONK, N.Y. and ITHACA, N.Y. ... IBM ) and Cornell University, a leader in dairy ... combined with bioinformatics designed to help reduce the chances ... breaches. With the onset of this dairy project, Cornell ... the Consortium for Sequencing the Food Supply Chain, a ...
(Date:5/16/2017)... -- Veratad Technologies, LLC ( www.veratad.com ), an innovative and ... solutions, announced today they will participate as a sponsor ... May 17, 2017, in Washington D.C.,s ... Identity impacts the lives of billions of ... digital world, defining identity is critical to nearly every ...
Breaking Biology News(10 mins):