Nucleic acid binding surface and dimer interface revealed by CRISPR-associated CasB protein structures

FEBS Lett. 2012 Nov 16;586(22):3956-61. doi: 10.1016/j.febslet.2012.09.041. Epub 2012 Oct 16.

Abstract

The CRISPR system is an adaptive RNA-based microbial immune system against invasive genetic elements. CasB is an essential protein component in Type I-E Cascade. Here, we characterize CasB proteins from three different organisms as non-specific nucleic acid binding proteins. The Thermobifida fusca CasB crystal structure reveals conserved positive surface charges, which we show are important for its nucleic acid binding function. EM docking reveals that CasB dimerization aligns individual nucleic acid binding surfaces into a curved, elongated binding surface inside Type I-E Cascade, consistent with the putative functions of CasB in ds-DNA recruitment and crRNA-DNA duplex formation steps.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actinomycetales / genetics
  • Actinomycetales / metabolism
  • Amino Acid Sequence
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Base Sequence
  • Binding Sites / genetics
  • Chromatography, Gel
  • Cryoelectron Microscopy
  • Crystallography, X-Ray
  • DNA / chemistry
  • DNA / genetics
  • DNA / metabolism
  • Electrophoretic Mobility Shift Assay
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Escherichia coli Proteins / chemistry
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism
  • Models, Molecular
  • Molecular Sequence Data
  • Mutation
  • Nucleic Acids / chemistry*
  • Nucleic Acids / genetics
  • Nucleic Acids / metabolism
  • Protein Binding
  • Protein Multimerization*
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • RNA / chemistry
  • RNA / genetics
  • RNA / metabolism
  • Repetitive Sequences, Nucleic Acid*
  • Sequence Homology, Amino Acid
  • Surface Properties
  • Thermus thermophilus / genetics
  • Thermus thermophilus / metabolism

Substances

  • Bacterial Proteins
  • CasB protein, E coli
  • Escherichia coli Proteins
  • Nucleic Acids
  • RNA
  • DNA