Biochemical and structural characterization of a keratin-degrading M32 carboxypeptidase from Fervidobacterium islandicum AW-1

Yong Jik Lee, Immanuel Dhanasingh, Jin Soo Ahn, Hyeon Su Jin, Jin Myung Choi, Sung Haeng Lee, Dong Woo Lee

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20 Citations (Scopus)


Comparative genomics of the keratin-degrading extremophilic eubacterium Fervidobacterium islandicum AW-1 and the closely related Fervidobacterium nodosum with no keratinolytic activity suggested that the FIAW1-1600 gene encoding a carboxypeptidase (CP) plays an important role in keratin degradation. The presumptive 489 amino acid sequence of the gene showed a conserved HEXXH motif with low levels of sequence identity (<38%) to reported thermostable M32 CPs. To identify its functional role, the FIAW1-1600 gene was overexpressed in Escherichia coli, and the recombinant enzyme was purified and characterized in detail. F. islandicum AW-1 CP (FisCP) formed a homodimer with a molecular mass of 107 kDa, and its apoenzyme exhibited maximal activity at 80 °C and pH 7.0 in the presence of Co2+. This metalloenzyme mainly cleaved the C-termini of peptides with a basic amino acid sequence. The crystal structure of FisCP at 2.2 Å resolution showed high levels of structural similarities (root-mean-square deviations of <1.7 Å) to those of other M32 CP homologs. Remarkably, the enzyme significantly enhanced the degradation of native chicken feathers. This study suggests that FisCP, a keratinolytic member of the thermostable M32 CP family, plays an important role in keratin degradation for cellular metabolism in F. islandicum AW-1.

Original languageEnglish
Pages (from-to)927-933
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number4
Publication statusPublished - 2015 Dec 25

Bibliographical note

Funding Information:
We thank the Beamline (PLS-5C and 7A) staff at the Pohang Light Source for technical support during data collection. This work was supported by the National Agenda Program for Agricultural R&D ( PJ0097672014 ) from the Rural Development Administration, Korea.

Publisher Copyright:
© 2015 Elsevier Inc. All rights reserved.

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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