ARTICLE 1H, 15N and 13C backbone chemical shift assignment of titin domains A59–A60 and A60 alone

Abstract The giant protein titin is the third most abun-dant protein of vertebrate striated muscle. The titin mole-cule is[1 lm long and spans half the sarcomere, from the Z-disk to the M-line, and has important roles in sarcomere assembly, elasticity and intracellular signaling. In the A-band of the sarcomere titin is attached to the thick fila-ments and mainly consists immunoglobulin-like and fibronectin type III-like domains. These are mostly arran-ged in long-range patterns or ‘super-repeats’. The large super-repeats each contain 11 domains and are repeated 11 times, thus forming nearly half the titin molecule. Through interactions with myosin and C-protein, they are involved in thick filament assembly. The importance of titin in muscle assembly is highlighted by the effect of mutations in the A-band portion, which are the commonest cause of dilated cardiomyopathy, affecting *1 in 250 (Herman et al. in N Engl J Med 366:619–628, 2012). Here we report backbone 15N, 13C and 1H chemical shift and 13Cb assignments for the A59–A60 domain tandem from the titin A59–A69 large super-repeat, completed using triple resonance NMR. Since, some regions of the backbone remained unassigned in A60 domain of the complete A59– A60 tandem, a construct containing a single A60 domain, A60sd, was also studied using the same methods. Consid-erably improved assignment coverage was achieved using A60sd due to its lower mass and improved molecular tumbling rate; these assignments also allowed the analysis of inter-domain interactions using chemical shift mapping against A59–A60