An N-terminal, 830 residues intrinsically disordered region of the cytoskeleton-regulatory protein supervillin contains Myosin II- and F-actin-binding sites

Abstract

Supervillin, the largest member of the villin/gelsolin family, is a cytoskeleton regulating, peripheral membrane protein. Supervillin increases cell motility and promotes invasive activity in tumors. Major cytoskeletal interactors, including filamentous actin and myosin II, bind within the unique supervillin amino terminus, amino acids 1–830. The structural features of this key region of the supervillin polypeptide are unknown. Here, we utilize circular dichroism and bioinformatics sequence analysis to demonstrate that the N-terminal part of supervillin forms an extended intrinsically disordered region (IDR). Our combined data indicate that the N-terminus of human and bovine supervillin sequences (positions 1–830) represents an IDR, which is the largest IDR known to date in the villin/gelsolin family. Moreover, this result suggests a potentially novel mechanism of regulation of myosin II and F-actin via the intrinsically disordered N-terminal region of hub protein supervillin.

Keywords:

• intrinsically disordered proteins
• intrinsically disordered regions
• hub proteins
• cytoskeleton
• F-actin

Acknowledgments

SF acknowledges RSP funding support from Western Washington University in 2011. For OVG and MYuL, the support came in part from the Russian Foundation for Basic Research (Grant No. 11-04-00763), Russian Academy of Sciences (programs “Molecular and Cell Biology” (01200959110) and “Fundamental Sciences to Medicine”). SLS acknowledges the support from Murdock Charitable Trust and EJL acknowledges support from the National Institutes of Health (GM033048) and the Department of Cell and Developmental Biology, UMASS Medical School. Useful feedback from Tara C. Smith (UMASS Medical School, Worcester, MA, USA) is thankfully acknowledged. The authors are grateful to Dr. C. James McKnight (Boston University Medical School, Boston, MA, USA) for assistance with initiating the project and fruitful discussions. We also express gratitude to Dr. Olga Gursky (Boston University Medical School, Boston, MA, USA) as well as Dr. Roland K. Strong and Tim Vanden Bos (Fred Hutchinson Cancer Research Center, Seattle, WA) for their help with CD recordings of our samples. Dr. Olga Platonova (STRUBI, Oxford, Great Britain), David Gruber (Western Washington University, Bellingham, WA, USA), and Kristen Brewster (Mt. Hood Community College, Gresham, OR, USA) are acknowledged for their assistance in expression and purification of the protein samples.

Notes

These authors Stanislav O. Fedechkin and Jacob Brockerman contributed equally to the work.