cyanide hydratase from Neurospora crassa forms a helix which has a dimeric repeat

• Published in: Applied microbiology and biotechnology 2009-02, Vol.82 (2), p.271-278
• Main Authors: Dent, Kyle C, Weber, Brandon W, Benedik, Michael J, Sewell, B. Trevor
• Format: Article
• Language: English
• Subjects: 3d protein reconstruction; Amino Acid Sequence; Amino acids; Ammonia; Biological and medical sciences; Bioremediation; Biotechnologically Relevant Enzymes and Proteins; Biotechnology; Chromatography; Cyanide; Cyanide hydratase; Cyanides; Enzymes; Escherichia coli - genetics; Escherichia coli - metabolism; Fibers; Fundamental and applied biological sciences. Psychology; Fungal Proteins - chemistry; Fungal Proteins - genetics; Fungal Proteins - isolation & purification; Fungal Proteins - metabolism; Fungi; Gene Expression; Hydro-Lyases - chemistry; Hydro-Lyases - genetics; Hydro-Lyases - isolation & purification; Hydro-Lyases - metabolism; Life Sciences; Microbial Genetics and Genomics; Microbiology; Models, Molecular; Molecular Conformation; Molecular Sequence Data; Neurospora crassa; Neurospora crassa - chemistry; Neurospora crassa - enzymology; Nitrilase; Proteins; Sequence Alignment; Studies
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-008-1735-4

The fungal cyanide hydratases form a functionally specialized subset of the nitrilases which catalyze the hydrolysis of cyanide to formamide with high specificity. These hold great promise for the bioremediation of cyanide wastes. The low resolution (3.0 nm) three-dimensional reconstruction of negatively stained recombinant cyanide hydratase fibers from the saprophytic fungus Neurospora crassa by iterative helical real space reconstruction reveals that enzyme fibers display left-handed D₁ S₅.₄ symmetry with a helical rise of 1.36 nm. This arrangement differs from previously characterized microbial nitrilases which demonstrate a structure built along similar principles but with a reduced helical twist. The cyanide hydratase assembly is stabilized by two dyadic interactions between dimers across the one-start helical groove. Docking of a homology-derived atomic model into the experimentally determined negative stain envelope suggests the location of charged residues which may form salt bridges and stabilize the helix.