A new mode of SAM domain mediated oligomerization observed in the CASKIN2 neuronal scaffolding protein

Ekaterina Smirnova; Jamie J. Kwan; Ryan Siu; Xin Gao; Georg Zoidl; Borries Demeler; Vivian Saridakis; Logan W. Donaldson

doi:10.1186/s12964-016-0140-3

A new mode of SAM domain mediated oligomerization observed in the CASKIN2 neuronal scaffolding protein

Ekaterina Smirnova
, Jamie J. Kwan
, Ryan Siu
, Xin Gao
, Georg Zoidl
, Borries Demeler
, Vivian Saridakis
, Logan W. Donaldson

Chemistry and Biochemistry

Research output: Contribution to journal › Article › peer-review

16 Scopus citations

Abstract

Background: CASKIN2 is a homolog of CASKIN1, a scaffolding protein that participates in a signaling network with CASK (calcium/calmodulin-dependent serine kinase). Despite a high level of homology between CASKIN2 and CASKIN1, CASKIN2 cannot bind CASK due to the absence of a CASK Interaction Domain and consequently, may have evolved undiscovered structural and functional distinctions. Results: We demonstrate that the crystal structure of the Sterile Alpha Motif (SAM) domain tandem (SAM1-SAM2) oligomer from CASKIN2 is different than CASKIN1, with the minimal repeating unit being a dimer, rather than a monomer. Analytical ultracentrifugation sedimentation velocity methods revealed differences in monomer/dimer equilibria across a range of concentrations and ionic strengths for the wild type CASKIN2 SAM tandem and a structure-directed double mutant that could not oligomerize. Further distinguishing CASKIN2 from CASKIN1, EGFP-tagged SAM tandem proteins expressed in Neuro2a cells produced punctae that were distinct both in shape and size. Conclusions: This study illustrates a new way in which neuronal SAM domains can assemble into large macromolecular assemblies that might concentrate and amplify synaptic responses.

Original language	English
Article number	17
Journal	Cell Communication and Signaling
Volume	14
Issue number	1
DOIs	https://doi.org/10.1186/s12964-016-0140-3
State	Published - Aug 22 2016

Funding

This work was supported by the Canadian Institutes of Health Research MOP-81250 to LWD. GZ is a Canada Research Chair in Molecular and Cellular Neuroscience. XG is supported by King Abdullah University of Science and Technology. The development of the UltraScan Science Gateway is supported by the NSF grant DAC-1339649 to BD. Supercomputer time allocations were provided through NSF grant TG-MCB070039 to BD. The Center for Analytical Ultracentrifugation of Macromolecular Assemblies at the University of Texas Health Science Center at San Antonio is supported by San Antonio Cancer Institute grant P30 CA054174.

Funders	Funder number
P30 CA054174
DAC-1339649
P30CA054174
Canadian Institutes of Health Research	MOP-81250
King Abdullah University of Science and Technology

Keywords

Analytical ultracentrifugation
Cell signaling
Crystal structure
Neuroscience
Nuclear magnetic resonance
Protein structure
Scaffold protein

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10.1186/s12964-016-0140-3

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title = "A new mode of SAM domain mediated oligomerization observed in the CASKIN2 neuronal scaffolding protein",

abstract = "Background: CASKIN2 is a homolog of CASKIN1, a scaffolding protein that participates in a signaling network with CASK (calcium/calmodulin-dependent serine kinase). Despite a high level of homology between CASKIN2 and CASKIN1, CASKIN2 cannot bind CASK due to the absence of a CASK Interaction Domain and consequently, may have evolved undiscovered structural and functional distinctions. Results: We demonstrate that the crystal structure of the Sterile Alpha Motif (SAM) domain tandem (SAM1-SAM2) oligomer from CASKIN2 is different than CASKIN1, with the minimal repeating unit being a dimer, rather than a monomer. Analytical ultracentrifugation sedimentation velocity methods revealed differences in monomer/dimer equilibria across a range of concentrations and ionic strengths for the wild type CASKIN2 SAM tandem and a structure-directed double mutant that could not oligomerize. Further distinguishing CASKIN2 from CASKIN1, EGFP-tagged SAM tandem proteins expressed in Neuro2a cells produced punctae that were distinct both in shape and size. Conclusions: This study illustrates a new way in which neuronal SAM domains can assemble into large macromolecular assemblies that might concentrate and amplify synaptic responses.",

keywords = "Analytical ultracentrifugation, Cell signaling, Crystal structure, Neuroscience, Nuclear magnetic resonance, Protein structure, Scaffold protein",

author = "Ekaterina Smirnova and Kwan, \{Jamie J.\} and Ryan Siu and Xin Gao and Georg Zoidl and Borries Demeler and Vivian Saridakis and Donaldson, \{Logan W.\}",

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doi = "10.1186/s12964-016-0140-3",

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T1 - A new mode of SAM domain mediated oligomerization observed in the CASKIN2 neuronal scaffolding protein

AU - Smirnova, Ekaterina

AU - Kwan, Jamie J.

AU - Siu, Ryan

AU - Gao, Xin

AU - Zoidl, Georg

AU - Demeler, Borries

AU - Saridakis, Vivian

AU - Donaldson, Logan W.

PY - 2016/8/22

Y1 - 2016/8/22

N2 - Background: CASKIN2 is a homolog of CASKIN1, a scaffolding protein that participates in a signaling network with CASK (calcium/calmodulin-dependent serine kinase). Despite a high level of homology between CASKIN2 and CASKIN1, CASKIN2 cannot bind CASK due to the absence of a CASK Interaction Domain and consequently, may have evolved undiscovered structural and functional distinctions. Results: We demonstrate that the crystal structure of the Sterile Alpha Motif (SAM) domain tandem (SAM1-SAM2) oligomer from CASKIN2 is different than CASKIN1, with the minimal repeating unit being a dimer, rather than a monomer. Analytical ultracentrifugation sedimentation velocity methods revealed differences in monomer/dimer equilibria across a range of concentrations and ionic strengths for the wild type CASKIN2 SAM tandem and a structure-directed double mutant that could not oligomerize. Further distinguishing CASKIN2 from CASKIN1, EGFP-tagged SAM tandem proteins expressed in Neuro2a cells produced punctae that were distinct both in shape and size. Conclusions: This study illustrates a new way in which neuronal SAM domains can assemble into large macromolecular assemblies that might concentrate and amplify synaptic responses.

AB - Background: CASKIN2 is a homolog of CASKIN1, a scaffolding protein that participates in a signaling network with CASK (calcium/calmodulin-dependent serine kinase). Despite a high level of homology between CASKIN2 and CASKIN1, CASKIN2 cannot bind CASK due to the absence of a CASK Interaction Domain and consequently, may have evolved undiscovered structural and functional distinctions. Results: We demonstrate that the crystal structure of the Sterile Alpha Motif (SAM) domain tandem (SAM1-SAM2) oligomer from CASKIN2 is different than CASKIN1, with the minimal repeating unit being a dimer, rather than a monomer. Analytical ultracentrifugation sedimentation velocity methods revealed differences in monomer/dimer equilibria across a range of concentrations and ionic strengths for the wild type CASKIN2 SAM tandem and a structure-directed double mutant that could not oligomerize. Further distinguishing CASKIN2 from CASKIN1, EGFP-tagged SAM tandem proteins expressed in Neuro2a cells produced punctae that were distinct both in shape and size. Conclusions: This study illustrates a new way in which neuronal SAM domains can assemble into large macromolecular assemblies that might concentrate and amplify synaptic responses.

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KW - Cell signaling

KW - Crystal structure

KW - Neuroscience

KW - Nuclear magnetic resonance

KW - Protein structure

KW - Scaffold protein

UR - https://www.scopus.com/pages/publications/84983371942

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DO - 10.1186/s12964-016-0140-3

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AN - SCOPUS:84983371942

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A new mode of SAM domain mediated oligomerization observed in the CASKIN2 neuronal scaffolding protein

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Keywords

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