Complete sequential assignment and secondary structure prediction of the cannulae forming protein CanA from the hyperthermophilic archaeon Pyrodictium abyssi

CanA from Pyrodictium abyssi forms a heat-resistant organic hollow-fiber network together with CanB and CanC. An N-terminally truncated construct of CanA (K 1 -CanA) gave NMR spectra of good quality that could be assigned by three-dimensional NMR methods on 15 N and 13 C– 15 N enriched protein. We assigned the chemical shifts of 96% of all backbone 1 H N atoms, 98% of all backbone 15 N atoms, 100% of all 13 C α atoms, 100% of all 1 H α atoms, 90% of all 13 C′ atoms, and 100% of the 13 C 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 K 1 -CanA of 6% helices, 44% β-pleated sheets, and 50% coils.