![]()
|
|
||||||||
(Received for publication, October 7, 1994; and in revised form, June 7, 1995) The terminase holoenzyme of bacteriophage
Volume 270,
Number 34,
Issue of August 25, pp. 20059-20066, 1995
©1995 by The American Society for Biochemistry and Molecular Biology, Inc.
Terminase and Its
Subunits
KINETIC AND BIOCHEMICAL ANALYSIS
is a
multifunctional protein composed of two subunits, gpNu1 and gpA. In
vitro, under certain conditions, terminase can render DNAs from
various sources, of varying lengths and termini, resistant to
degradation by high concentrations of DNase I. This reaction is
completely dependent on the presence of terminase, proheads, a
hydrolyzable triphosphate, and a divalent metal ion, and we propose
that it is the result of translocation of DNA into proheads by
terminase. This reaction is stoichiometric with respect to terminase,
DNA, and proheads and can be supported by all deoxyribo- and
ribonucleoside triphosphates, but not by the corresponding diphosphates
or nonhydrolyzable ATP analogs. Mg
and Ca
promote the reaction, but Mn
and Zn
do not. In the absence of spermidine, translocase activity is
low, but addition of the Escherichia coli protein integration
host factor (IHF) promotes specific translocation of only those DNA
fragments containing the terminase-binding site, cosB. When
spermidine is present, nonspecific translocation of DNA from any source
is stimulated. Under these conditions IHF no longer promotes
specificity, but translocation of only cosB-containing DNA
fragments can be restored by addition of small amounts of a dialyzed
and RNase-treated E. coli extract, suggesting that additional
host factor(s) may be involved in determination of packaging
specificity. To a limited extent, gpA alone can promote translocation,
but gpNu1, which has no translocase activity on its own, must be added
to approach the holoenzyme-like activity levels. Formation of viable
phage cannot be accomplished by gpA in the absence of gpNu1.
![]()
CiteULike
Complore
Connotea
Del.icio.us
Digg
Reddit
Technorati What's this?
This article has been cited by other articles:
![]() |
J. Kindt, S. Tzlil, A. Ben-Shaul, and W. M. Gelbart DNA packaging and ejection forces in bacteriophage PNAS, November 9, 2001; (2001) 241486298. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. L. Bain, N. Berton, M. Ortega, J. Baran, Q. Yang, and C. E. Catalano Biophysical Characterization of the DNA Binding Domain of gpNu1, a Viral DNA Packaging Protein J. Biol. Chem., June 1, 2001; 276(23): 20175 - 20181. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Kindt, S. Tzlil, A. Ben-Shaul, and W. M. Gelbart DNA packaging and ejection forces in bacteriophage PNAS, November 20, 2001; 98(24): 13671 - 13674. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| All ASBMB Journals | Molecular and Cellular Proteomics |
| Journal of Lipid Research | ASBMB Today |