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Solution dynamics and secondary structure of murine leukemia inhibitory factor: a four-helix cytokine with a rigid CD

D H Purvis1, B C Mabbutt

  • 1School of Biochemistry and Molecular Genetics, University of New South Wales, Sydney NSW 2052, Australia.

Biochemistry
|August 19, 1997
PubMed

Insights

Leukemia inhibitory factor (LIF) adopts a four-alpha-helix bundle structure in solution. Its N-terminal residues and AB loop exhibit high mobility, potentially influencing receptor interactions.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Molecular Biology

Background:

  • Leukemia inhibitory factor (LIF) is a cytokine crucial for various cellular processes, signaling through gp130 and a specific LIF receptor.
  • Understanding LIF's structure and dynamics is key to elucidating its biological functions and receptor interactions.

Purpose of the Study:

  • To determine the solution structure and backbone dynamics of recombinant murine Leukemia inhibitory factor (LIF).
  • To compare the solution structure with existing crystal structures and investigate the implications of its dynamics on receptor binding.

Main Methods:

  • Multidimensional homonuclear and 1H-15N heteronuclear Nuclear Magnetic Resonance (NMR) spectroscopy.
  • Assignment of 95% of backbone amide resonances.
  • Analysis of chemical shift data, NOE connectivities, and 15N relaxation times (T1, T2) and heteronuclear NOEs.

Main Results:

  • The solution structure of LIF reveals a four-alpha-helix bundle (helices A-D) with a flexible turn in the AB loop.
  • Conformations of helices A and D show subtle differences compared to the crystal structure.
  • LIF exhibits a rotational correlation time of 9.7 ps, with rigid alpha-helices and mobile N-terminal residues (Ser 1-Asn 21) and the AB loop.
  • The long CD loop is relatively rigid, unlike in related cytokines.

Conclusions:

  • The solution structure of LIF is characterized by a stable four-alpha-helix bundle with distinct flexible and rigid regions.
  • The observed dynamics, particularly the rigidity of the CD loop, may be critical for specific LIF receptor binding.
  • These findings provide insights into the structure-function relationship of LIF and its interaction with its receptor.

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