Molecular Structure of Spider Dragline SilkJeffery L. Yarger, Arizona State University, DMR 0805197

Dragline spider silk is one of the toughest materials known. The fiber’s impressive mechanical properties are thought to originate from the various folded structures formed by the two proteins that comprise the silk: major ampullate spidroin 1 and major ampullate spidroin 2 (MaSp1 and MaSp2). Our research group at ASU has recently solved the secondary structural elements found in MaSp1 and MaSp2 associated with repetitive poly(Gly-Ala), Gly-Gly-X and Gly-Pro-Gly-Ala motifs found in spider dragline silk.For the first time, 2D solid-state NMR experiments provide evidence for an elastin-like β-turn structure for the repetitive Gly-Pro-Gly-X-X motif prevalent in major ampullate spidroin 2 (MaSp2).

Chem Commun., 2010, 46, 6714-6716

(a) -sheet domains, the repetitive GGX motif of MaSp1 folds in a (b) disordered 31-helical structure and the (c) proposed type II -turn structure for the Gly-Pro-Gly-Ala region unique to MaSp2. The turn conformation in (c) is an optimized type II -turn with (i+1) = -81, (i+1) = 135, (i+2) = 73 and (i+2) = 20. (bottom) The 2D 15N/13C HETCOR spectrum of 13C/15N-proline labeled A. aurantia dragline silk. The 15N13C contact time was 1 ms.

Profs Jeff Yarger (PI) and Greg Holland (Co-PI) have mentored more than 20 students, teachers and researchers over the past 3 years work on spider silk proteins. Some pictures of students and high-school teachers that have been working in the lab during summer 2010 and 2011 are shown. All of the people pictured on the left have contributed to the spider silk protein project. This includes several underrepresented minor students and teachers. Highlights of ongoing outreach activities include:• Providing high-school teachers

with supplies for spider silk projects in their classroom.

• Spider silk demos at local high schools and junior high classrooms.

• Regular student tours of the NMR and MRI instruments.

2010 NSF & sfAZ Sponsored High School Summer Teachers Program(Gina Perlman, Retta Ward, Gladys Tordil, Jeff Yarger & Tapati Sen)

Undergraduate Research Students (2011):(Phakade Shange, Valerie Echols)

(right) Graduate Students:(Laura Beck & Xiangyan Shi)

(above) Summer 2010 Visiting Undergraduate Students

Structural NMR Studies of Spider Silk Fibers Jeffery L. Yarger, Arizona State University, DMR 0805197