Unusual domain pairing in a mutant of bovine lens gammaB-crystallin.
J Mol Biol
; 279(5): 1053-9, 1998 Jun 26.
Article
em En
| MEDLINE
| ID: mdl-9642083
ABSTRACT
beta gamma-Crystallins from the eye lens are proteins consisting of two domains joined by a short linker. All 3D structures solved so far reveal a similar pseudo-2-fold pairing of the domains, reflecting their presumed ancient origin from a single-domain homodimer. Here we report the 2.2 A X-ray structure of the N-terminal domain of gammaB-crystallin, bearing a mutation of a residue involved in domain contacts in the native molecule (Phe56Ala). It forms a crystallographic homodimer, yet the domain orientation is different from native beta gamma-crystallins. It is considered that the new orientation derives from two structural features. (1) The replacement of the bulky phenylalanine 56 by an alanine results in a different optimal hydrophobic packing of interface residues between identical domains. (2) The paired domains have extensions derived from the domain linker, each containing a proline conserved in gamma-crystallins, and the resulting steric constraints preclude a native-like pairing but support the new arrangement. These data highlight the pivotal role of interface residues and sequence extensions in overall domain assembly.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Conformação Proteica
/
Cristalinas
Limite:
Animals
Idioma:
En
Revista:
J Mol Biol
Ano de publicação:
1998
Tipo de documento:
Article
País de afiliação:
Reino Unido