Conformational specificity of the lac repressor coiled-coil tetramerization domain

Jie Liu, Qi Zheng, Yiqun Deng, Qunnu Li, Neville R. Kallenbach, Min Lu

Research output: Contribution to journalArticle

Abstract

Predictive understanding of how the folded, functional shape of a native protein is encoded in the linear sequence of its amino acid residues remains an unsolved challenge in modern structural biology. Antiparallel four-stranded coiled coils are relatively simple protein structures that embody a heptad sequence repeat and rich diversity for tertiary packing of α-helices. To explore specific sequence determinants of the lac repressor coiled-coil tetramerization domain, we have engineered a set of buried nonpolar side chains at the a-, d-, and e-positions into the hydrophobic interior of the dimeric GCN4 leucine zipper. Circular dichroism and equilibrium ultracentrifugation studies show that this core variant (GCN4-pAeLV) forms a stable tetrameric structure with a reversible and highly cooperative thermal unfolding transition. The X-ray crystal structure at 1.9 Å reveals that GCN4-pAeLV is an antiparallel four-stranded coiled coil of the lac repressor type in which the a, d, and e side chains associate by means of combined knobs-against-knobs and knobs-into-holes packing with a characteristic interhelical offset of 0.25 heptad. Comparison of the side chain shape and packing in the antiparallel tetramers shows that the burial of alanine residues at the e positions between the neighboring helices of GCN4-pAeLV dictates both the antiparallel orientation and helix offset. This study fills in a gap in our knowledge of the determinants of structural specificity in antiparallel coiled coils and improves our understanding of how specific side chain packing forms the teritiary structure of a functional protein.

Original languageEnglish (US)
Pages (from-to)14951-14959
Number of pages9
JournalBiochemistry
Volume46
Issue number51
DOIs
StatePublished - Dec 25 2007

Fingerprint

Lac Repressors
Knobs
Burial
Leucine Zippers
Proteins
Ultracentrifugation
Circular Dichroism
Alanine
Amino Acid Sequence
Hot Temperature
X-Rays
Crystal structure
Amino Acids
X rays

ASJC Scopus subject areas

  • Biochemistry

Cite this

Liu, J., Zheng, Q., Deng, Y., Li, Q., Kallenbach, N. R., & Lu, M. (2007). Conformational specificity of the lac repressor coiled-coil tetramerization domain. Biochemistry, 46(51), 14951-14959. https://doi.org/10.1021/bi701930d

Conformational specificity of the lac repressor coiled-coil tetramerization domain. / Liu, Jie; Zheng, Qi; Deng, Yiqun; Li, Qunnu; Kallenbach, Neville R.; Lu, Min.

In: Biochemistry, Vol. 46, No. 51, 25.12.2007, p. 14951-14959.

Research output: Contribution to journalArticle

Liu, J, Zheng, Q, Deng, Y, Li, Q, Kallenbach, NR & Lu, M 2007, 'Conformational specificity of the lac repressor coiled-coil tetramerization domain', Biochemistry, vol. 46, no. 51, pp. 14951-14959. https://doi.org/10.1021/bi701930d
Liu J, Zheng Q, Deng Y, Li Q, Kallenbach NR, Lu M. Conformational specificity of the lac repressor coiled-coil tetramerization domain. Biochemistry. 2007 Dec 25;46(51):14951-14959. https://doi.org/10.1021/bi701930d
Liu, Jie ; Zheng, Qi ; Deng, Yiqun ; Li, Qunnu ; Kallenbach, Neville R. ; Lu, Min. / Conformational specificity of the lac repressor coiled-coil tetramerization domain. In: Biochemistry. 2007 ; Vol. 46, No. 51. pp. 14951-14959.
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