Interaction of Escherichia coli host factor protein with oligoriboadenylates. Journal Article uri icon



  • The interaction of Escherichia coli host factor 1 with oligoadenylate [oligo(A)] was studied by fluorescence and filter retention techniques. The intrinsic fluorescence of the host factor is quenched by up to 60% by the addition of oligo(A). Fluorescence titrations at high protein concentrations (6 microM) give a saturation point of 14 A residues per host factor hexamer regardless of chain length or ionic strength. Nitrocellulose filter retention experiments at much lower concentrations (1 nM) indicate equimolar complexes form between (pA)l (12 less than l less than 27) and host factor hexamers. The smallest number of contiguous A residues which allows the formation of all favorable protein--RNA contacts is 16 at both low and high salt concentrations. At 0.1 M NaCl, the molar association constants are in the range of 10(10)--10(11) M-1 (15 less than l less than 27) and decrease only slightly with ionic strength, indicating a large nonionic component in the interaction. Cyclized (pA)l was shown to have a higher affinity for host factor than its linear counterparts when l is 18 or greater but a lower relative affinity when l is 15. This suggests that the binding site on the hexamer has a circular spatial orientation.

publication date

  • December 23, 1980

has subject area

has restriction

  • closed

Date in CU Experts

  • March 13, 2015 12:57 PM

Full Author List

  • de Haseth PL; Uhlenbeck OC

author count

  • 2

Other Profiles

International Standard Serial Number (ISSN)

  • 0006-2960

Additional Document Info

start page

  • 6138

end page

  • 6146


  • 19


  • 26