Structural analysis of ASCUT-1, a protein component of the cuticle of the parasitic nematode Ascaris lumbricoides.
CUT-1 from the intestinal parasitic nematode Ascaris lumbricoides is a protein component of the insoluble residue of the cuticle, cuticlin. It contains the CUT-1-like domain which is shared by members of a novel family of components of extracellular matrices. The structure and the thermal stability of recombinant CUT-1 from A. lumbricoides (ASCUT-1) were investigated by Fourier-transform infrared (FT-IR) and CD spectroscopy. The data revealed that the secondary structure of the protein at 20 degrees C, both as insoluble inclusion bodies or in soluble form, contains about 50% beta structure, 14% alpha-helix and 25% turns. A tendency of A. lumbricoides CUT-1 to form aggregates was documented by FT-IR spectroscopy which showed also that the addition of SDS disrupts these interactions. Near-ultraviolet CD spectra confirmed these data and suggested that phenylalanine residues are probably involved in intermolecular hydrophobic interactions responsible for the tendency of the protein to aggregate. Near-ultraviolet spectra showed also that part of the cysteine residues forms disulphide bridges responsible for the tertiary architecture of the protein. Finally, FT-IR and CD data revealed that ASCUT-1 is very stable at high temperatures. This stability and the tendency of ASCUT-1 to form aggregates suggest that these properties may be important for a protein which is a component of a particularly resistant extracellular matrix such as the nematode cuticle.
D'Auria
S
S
Istituto di Biochimica delle Proteine ed Enzimologia, CNR, Naples, Italy.
Rossi
M
M
Tanfani
F
F
Bertoli
E
E
Parise
G
G
Bazzicalupo
P
P
D000595:Amino Acid Sequence; D000818:Animals; D001200:Ascaris / Q000737:chemistry*; D029742:Caenorhabditis elegans Proteins; D002942:Circular Dichroism; D015801:Helminth Proteins / Q000737:chemistry*; D006358:Hot Temperature; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry; D013055:Spectrophotometry, Infrared
D029742:Caenorhabditis elegans Proteins; D015801:Helminth Proteins; D011994:Recombinant Proteins; C070207:CUT-1 protein, C elegans