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Structural study of MCPIP1 N-terminal conserved domain reveals a PIN-like RNase

Jiwei Xu1, Wei Peng, Yao Sun

  • 1National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.

Nucleic Acids Research
|May 8, 2012
PubMed

Insights

Monocyte chemoattractant protein-1-induced protein 1 (MCPIP1) acts as an RNase to regulate immune responses. Researchers determined the MCPIP1 RNase domain structure, revealing its catalytic center and RNA binding site.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Immunology

Background:

  • Monocyte chemoattractant protein-1-induced protein 1 (MCPIP1) is an RNase crucial for downregulating LPS-induced immune responses.
  • MCPIP1 targets IL-6 and IL-12b mRNAs, but its catalytic mechanism remains unclear due to the absence of high-resolution structures.

Purpose of the Study:

  • To elucidate the structural basis of MCPIP1's RNase activity.
  • To understand the catalytic mechanism and RNA substrate binding of MCPIP1.

Main Methods:

  • Determined the 3D crystal structure of the MCPIP1 N-terminal conserved RNase domain at 2.0 Å resolution.
  • Performed site-specific mutagenesis to verify the role of acidic residues in the catalytic center.
  • Investigated the function of a positively charged arm through alanine-scanning mutagenesis.

Main Results:

  • The MCPIP1 N-terminal conserved domain structure reveals homology with the PilT N-terminal domain.
  • Identified several acidic residues forming the RNase catalytic center, confirmed by mutagenesis.
  • A positively charged arm near the catalytic center is implicated in RNA substrate binding, as mutations partially abolished RNase activity.

Conclusions:

  • The determined structure provides atomic-level insights into the MCPIP1 RNase domain.
  • This work clarifies the catalytic center and RNA degradation mechanism of MCPIP1.
  • The findings enhance understanding of MCPIP1's role in immune response regulation.

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