Three-Dimensional Structure of Cofilin Bound to Monomeric Actin Derived by Structural Mass Spectrometry Data
The cytoskeletal protein, actin, has its structure and function regulated by cofilin. In the absence of an atomic resolution structure for the actin/cofilin complex, the mechanism of cofilin regulation is poorly understood. Theoretical studies based on the similarities of cofilin and gelsolin segment 1 proposed the cleft between subdomains 1 and 3 in actin as the cofilin binding site. We used radiolytic protein footprinting with mass spectrometry and molecular modeling to provide an atomic model of how cofilin binds to monomeric actin. Footprinting data suggest that cofilin binds to the cleft between subdomains 1 and 2 in actin and that cofilin induces further closure of the actin nucleotide cleft. Site-specific fluorescence data confirm these results. The model identifies key ionic and hydrophobic interactions at the binding interface, including hydrogen-bonding between His-87 of actin to Ser-89 of cofilin that may control the charge dependence of cofilin binding. This model and its implications fill an especially important niche in the actin field, owing to the fact that ongoing crystallization efforts of the actin/cofilin complex have so far failed. This 3D binary complex structure is derived from a combination of solution footprinting data and computational approaches and outlines a general method for determining the structure of such complexes.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 959491
- Report Number(s):
- BNL-82477-2009-JA; PNASA6; TRN: US1005747
- Journal Information:
- Proceedings of the National Academy of Sciences of the USA, Vol. 104, Issue 19; ISSN 0027-8424
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
74 ATOMIC AND MOLECULAR PHYSICS
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
ACTIN
ATOMIC MODELS
CLOSURES
CRYSTALLIZATION
FLUORESCENCE
MASS SPECTROSCOPY
NUCLEOTIDES
PROTEINS
REGULATIONS
RESOLUTION
SIMULATION
national synchrotron light source