Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10749270 | Biochemical and Biophysical Research Communications | 2015 | 25 Pages |
Abstract
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 Ã
resolution showed high levels of structural similarities (root-mean-square deviations of <1.7Â Ã
) 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.
Keywords
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Authors
Yong-Jik Lee, Immanuel Dhanasingh, Jin-Soo Ahn, Hyeon-Su Jin, Jin Myung Choi, Sung Haeng Lee, Dong-Woo Lee,