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New Tools for Experimental Phasing of Twinned Diffraction Data

Award Number: R21GM129649
ORGANIZATION: NATIONAL INSTITUTE OF GENERAL MEDICAL SCIENCES
OPDIV: NIH
AWARD CLASS: DISCRETIONARY
AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)
PERIOD OF PERFORMANCE START DATE: 09/23/2019
PERIOD OF PERFORMANCE END DATE: 08/31/2023

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New Tools for Experimental Phasing of Twinned Diffraction Data - Summary Crystallography is an indispensable tool in modern structural biology, allowing for precise determination of molecular interactions in proteins. The majority of the computational crystallographic tools available have been developed on the prerequisite that the diffraction data is free from pathologies such as twinning. For the detection of twinned data and refinement of structures, excellent software is already available, but for more upstream tasks, no general‐ purpose tools are available. The absence of tools that allow handling of twinned data has resulted in practical difficulties when solving structures from such data. This proposal addresses this critical gap by developing twinning‐aware tools and algorithms for all mainstream crystallographic tasks for which no such tools exist. We propose to adopt and extend existing density modification and heavy atom determination methods such that they are suited for handling twinned data. The proposed algorithm propagates vital prior information from real space all the way into data space, numerically stabilizing an otherwise ill‐conditioned detwinning step using a regularization approach. To provide the community with a full complement of tools for de novo phasing, heavy atom refinement and phasing strategies will be addressed by developing and evaluating numerical techniques needed for the twinned‐SAD likelihood function. This problem will be addressed using an adaptive quadrature approach.


Issue Date FY	Funding FY	Legal Entity Name	Legal Entity Address	Legal Entity City	Legal Entity State	Legal Entity Zip Code	Legal Entity COUNTY	Legal Entity COUNTRY	Assistance Listing	Award Code	Budget Year	Action Date	Action Type	Action Amount

Issue Date FY: 2024 ( Subtotal = -$61,120 )
2024	2020	THE REGENTS OF THE UNIVERSITY OF CALIFORNIA	1 CYCLOTRON RD	BERKELEY	CA	94720	ALAMEDA	USA	Biomedical Research and Research Training	000	2	1/11/2024	NON-COMPETING CONTINUATION	-$61,120
														Subtotal = -$61,120

Issue Date FY: 2023 ( Subtotal = $0 )
2023	2020	REGENTS OF THE UNIVERSITY OF CALIFORNIA, THE	1 CYCLOTRON RD	BERKELEY	CA	94720	ALAMEDA	USA	Biomedical Research and Research Training	000	2	10/20/2022	NON-COMPETING CONTINUATION	$0
														Subtotal = $0

Issue Date FY: 2020 ( Subtotal = $301,401 )
2020	2020	REGENTS OF THE UNIVERSITY OF CALIFORNIA, THE	1 CYCLOTRON RD	BERKELEY	CA	94720	ALAMEDA	USA	Biomedical Research and Research Training	000	2	8/19/2020	NON-COMPETING CONTINUATION	$301,401
														Subtotal = $301,401

Issue Date FY: 2019 ( Subtotal = $254,483 )
2019	2019	REGENTS OF THE UNIVERSITY OF CALIFORNIA, THE	1 CYCLOTRON RD	BERKELEY	CA	94720	ALAMEDA	USA	Biomedical Research and Research Training	000	1	9/23/2019	NEW	$254,483
														Subtotal = $254,483

Grand Total All Awards = $494,764

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New Tools for Experimental Phasing of Twinned Diffraction Data

Award Number: R21GM129649

ORGANIZATION: NATIONAL INSTITUTE OF GENERAL MEDICAL SCIENCES

OPDIV: NIH

AWARD CLASS: DISCRETIONARY

AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)

PERIOD OF PERFORMANCE START DATE: 09/23/2019

PERIOD OF PERFORMANCE END DATE: 08/31/2023

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