Stabilities of HIV-1 DIS type RNA loop-loop interactions in vitro and in vivo

Area of Science:

• Molecular Biology
• Biochemistry
• Virology

Background:

• RNA loop-loop interactions are vital for tertiary structure formation and molecular recognition.
• Kissing complexes, a type of RNA loop-loop interaction, play a role in processes like viral genome dimerization.

Purpose of the Study:

• To investigate the influence of flanking nucleotides on the stability and ion dependence of RNA loop-loop interactions.
• To correlate in vitro determined stabilities with in vivo properties using a yeast RNA-hybrid system.
• To identify stable kissing complex motifs relevant to HIV genome dimerization.

Main Methods:

• Determined the stability of various loop-loop interactions with a constant core sequence and variable flanking nucleotides.
• Measured stability in 1 M Na+ and near physiological Mg2+ concentrations.
• Utilized a yeast RNA-hybrid system to assess in vivo activity (beta-galactosidase levels) and compared it with in vitro melting temperatures.

Main Results:

• Flanking bases significantly affect the stability and ion dependence of kissing complexes.
• In vitro determined stabilities generally correlate well with in vivo measurements in yeast cells.
• Naturally occurring HIV-1 DIS MAL and LAI derived loops with the motif (5' A(A)/(G)N6A 3') exhibit the highest stability.

Conclusions:

• In vitro stability measurements are reliable indicators of in vivo RNA-RNA interaction properties.
• Stable kissing complexes, particularly those found in HIV-1, are critical for viral genome dimerization.
• The study highlights the importance of flanking sequences in modulating RNA interaction stability.