Abstract
A helix-destabilizing protein, HD40 (Mr 40,000), isolated from the cytoplasm of Artemia salina (Marvil, D.K., Nowak, L., and Szer, W. (1980) J. Biol. Chem. 255, 6466-6472) stoichiometrically disrupts the secondary structures of synthetic single-stranded and helical polynucleotides (e.g. poly(rA), poly(dA), poly(rC), poly(dC), and poly(rU)) as well as those of natural polynucleotides (e.g. MS2 RNA and phi X174 viral DNA). The conformations of double-stranded DNA and double- or triple-stranded synthetic polynucleotides are not affected by the protein. Formation of duplexes, e.g. poly(rA . rU), is prevented by HD40 at 25 to 50 mM but not at 100 to 140 mM NaCl. The unwinding of the residual secondary structure of RNA and DNA by HD40 is not highly cooperative and has a stoichiometry of one HD40 per 12 to 15 nucleotides. The addition of HD40 in excess of 1 molecule per 12 to 15 nucleotides results in the cooperative formation of distinct bead-like structures along the nucleic acid strand. The beads are about 20 nm in diameter with a center to center distance of about 40 nm. The appearance of the beads is not accompanied by any spectral changes (CD and UV) beyond those obtained at a stoichiometry of one HD40 molecule per 12 to 15 nucleotides.
Highlights
11. INTERACTION WITH NUCLEIC ACIDS*In this communication, The conformations of double-stranded DNA and dou- we report that theformation of a complex withprotein HD40 ble-ortriple-strandedsyntheticpolynucleotidesare not aected by the protein
A helix-destabilizing protein, HD40 (Mr 40,000), iso- DNA these proteins destabilize double-stranded DNAby lated from the cytoplasm oAfrtemM salina
The addition of HD40 in results in considerable disruption of the secondary structure of a number of helical and stacked single-stranded ribo- and deoxy~ibopolynucleotides.We estimate from CD and UV titrations that theprotein occupies a site about12 to 15 nucleotides long when the polynucleotide is maximally unwound
Summary
In this communication, The conformations of double-stranded DNA and dou- we report that theformation of a complex withprotein HD40 ble-ortriple-strandedsyntheticpolynucleotidesare not aected by the protein. The addition of HD40 in results in considerable disruption of the secondary structure of a number of helical and stacked single-stranded ribo- and deoxy~ibopolynucleotides.We estimate from CD and UV titrations that theprotein occupies a site about to 15 nucleotides long when the polynucleotide is maximally unwound. Whenmore than one protein is added per 12 nucleotides, excess of 1 moleculeper 12 to 15 nucleotides results in electron microscopy reveals that, in contrast to other known the cooperative formation of distinct bead-like struc- helix-destabilizing proteins, HD40forms regularly spaced tures alongthe nucleic acid stranTdh.e beads are aboutbeadlike structures of about 20 nm in diameter along the 20 nm in diameter with a center to center distance of entire length of the polynucleotide. About 40 nm.The appearanceof the beadsis not accompanied by any spectral changes (CD and W) beyond
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
