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The determinants of the oligomeric structure in Hsp16.5 are encoded in the α‐crystallin domain
Author(s) -
Koteiche Hanane A,
Mchaourab Hassane S
Publication year - 2002
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(02)02688-1
Subject(s) - oligomer , crystallin , trimer , site directed spin labeling , protein subunit , chemistry , heat shock protein , protein structure , biophysics , biology , biochemistry , dimer , gene , organic chemistry , membrane
The determinants of the oligomeric assembly of Hsp16.5, a small heat‐shock protein (sHSP) from Methanococcus jannaschii , were explored via site‐directed truncation and site‐directed spin labeling. For this purpose, subunit contacts around the two‐, three‐ and four‐fold symmetry axes were fingerprinted using patterns of proximities between nitroxide spin labels introduced at selected sites. The lack of change in this fingerprint in an N‐terminal truncation of the protein demonstrates that the interactions are encoded in the α‐crystallin domain. In contrast, the truncation of the N‐terminal domain of Mycobacterium tuberculosis Hsp16.3, a bacterial sHSP with an equally short N‐terminal region, results in the dissociation of the oligomer to a trimer. These results, in conjunction with those from previous truncation studies in mammalian sHSP, suggest that as the α‐crystallin domain evolved to encode a smaller basic unit than the overall oligomer, the control of the assembly and dynamics of the oligomeric structure became encoded in the N‐terminal domain.