Biophysics

Molecular Yoga

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Science  12 Feb 2010:
Vol. 327, Issue 5967, pp. 763
DOI: 10.1126/science.327.5967.763-a
CREDIT: GRINTHAL ET AL., PROC. NATL. ACAD. SCI. U.S.A. 107, 10.1073/PNAS.0914073107 (2010)

The influence of tremendous advances in biological crystallography—most notably of membrane proteins and of large complexes of nucleic acids and proteins—has been profound. Perhaps too much so, for the glittering array of colorful macromolecules has tended to obscure the fact that they are constantly stretching, contracting, bending, or twisting.

Using molecular dynamics and normal mode analysis, Grinthal et al. illustrate the potential biological impact of these restless movements. Protein phosphatase 2A (PP2A) consists of a catalytic subunit (yellow), a regulatory subunit (green), and the PR65 scaffold (blue). This last component contains 15 repeats of a two-helix unit and adopts a curved solenoid shape. The lowest-frequency mode of the PP2A heterotrimer combines torsion and flexion of PR65, and the effect is to repetitively open and close the catalytic site (red) located at the interface between the other two subunits. Tuning these motions either by transiently applying force or via mutation within the interhelix linkages would result in what might be called an elasto-steric regulation of enzyme activity.

Proc. Natl. Acad. Sci. U.S.A. 107, 10.1073/pnas.0914073107 (2010).

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