Biochemical characterization and helix stabilizing properties of HSNP-C ' from the thermoacidophilic archaeon Sulfolobus acidocaldarius

Helix stabilizing nucleoid protein HSNP-C' from the thermophilic archaeon S ulfolobus acidocaldarius has been characterized with respect to its interac tions with nucleic acids by gel retardation assay, affinities to immobilize d matrices, electron microscopy, and fluorescence titration. The amino acid s implicated in the DNA binding site of the protein have been shown by sele ctively modifying specific amino acyl functional groups and looking at thei r effects on the DNA binding properties of the protein, Lysine, arginine, t ryptophan, and tyrosine residues of the protein HSNP-C' were modified with pyridoxal-5-phosphate; 2,3-butanedione; BNPS-skatole; and tetranitromethane , respectively. The modification of residues was assessed according to stan dard procedures, The effect of the chemical modification on the function of the protein HSNP-C' with respect to DNA protein interactions was studied a nd the results indicate the definite involvement of tyrosines and also the significant involvement of the flanking tryptophan residues in the DNA bind ing domain on the protein, (C) 2000 Academic Press.