Complete sequential assignment and secondary structure prediction of the cannulae forming protein CanA from the...

CanA from Pyrodictium abyssi forms a heat-resistant organic hollow-fiber network together with CanB and CanC. An N-terminally truncated construct of CanA (K₁-CanA) gave NMR spectra of good quality that could be assigned by three-dimensional NMR methods on ¹⁵N and ¹³C-¹⁵N enriched protein. We assigned the chemical shifts of 96% of all backbone ¹H^N atoms, 98% of all backbone ¹⁵N atoms, 100% of all ¹³C^α atoms, 100% of all ¹H^α atoms, 90% of all ¹³C' atoms, and 100% of the ¹³C^β atoms. Two short helices and 10 β-strands are estimated from an analysis of the chemical shifts leading to a secondary structure content of K₁-CanA of 6% helices, 44% β-pleated sheets, and 50% coils.