NMR resonance assignments of the human high mobility group protein HMGA1

Human HMGA1 is a 107-residue, non-histone chromatin nuclear factor with a wide sphere of influence including embryogenesis, apoptosis, differentiation, cell proliferation, and cancer development (Reeves, 2001). Because of the repetitive nature of the three DNA-binding domains, strings of glutamic acid residues at the C-terminus, and its unstructured nature in the absence of A-T rich regions of DNA and/or other proteins, backbone assignment for HMGA1 was challenging. Especially useful was the HNN experiment (Planchal et al., 2001), a set of truncated HMGA1 constructs, and some high resolution data collected at a ¹H resonance frequency of 900 MHz. Except for absolute assignment of R60 and R86, all 82 amide were assigned to cross peaks in the ¹H-¹⁵N HSQC spectrum and many of the side chain ¹³C and ¹H resonances were assigned (BMRB code xxxx). The intensity of the amide cross peaks for residues E3 – S9 and S64 – K67 were much weaker than the other amide cross peaks in the ¹H-¹⁵N HSQC spectrum suggesting that even in this unstructured protein there are regions experiencing motion different from the molecule as a whole.