Mapping the Distribution of Conformational Information throughout a Protein Sequence

GEBHARD LEOPOLDO G.; RISSO VALERIA A.; SANTOS JAVIER; FERREYRA RAUL G.; NOGUERA MARTIN E.; ERMACORA MARIO R.

JOURNAL OF MOLECULAR BIOLOGY

Elsevier

Año: 2006 vol. 358 p. 280 - 288

0022-2836

The three-dimensional structure of protein is encoded in the sequence, but many amino acid residues carry no essential conformational information, and the identity of those that are structure-determining is elusive. By circular permutation and terminal deletion, we produced and purified 25 Bacillus licheniformis b-lactamase (ESBL) variants that lack 5?21 contiguous residues each, and collectively have 82% of the sequence and 92% of the non-local atom?atom contacts eliminated. Circular dichroism and size-exclusion chromatography showed that most of the variants form conformationally heterogeneous mixtures, but by measuring catalytic constants, we found that all populate, to a greater or lesser extent, conformations with the essential features of the native fold. This suggests that no segment of the ESBL sequence is essential to the structure as a whole, which is congruent with the notion that local information and modular organization can impart most of the tertiary fold specificity and cooperativity.