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 N-15 and C-13-N-15 enriched protein. We assigned the chemical shifts of 96% of all backbone H-1(N) atoms, 98% of all backbone N-15 atoms, 100% of all C-13(alpha) atoms, 100% of all H-1(alpha) atoms, 90% of all C-13 ' atoms, and 100% of the C-13(beta) atoms. Two short helices and 10 beta-strands are estimated from an analysis of the chemical shifts leading to a secondary structure content of K-1-CanA of 6% helices, 44% beta-pleated sheets, and 50% coils.