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1994-08-27
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Document 0700
DOCN M9480700
TI Structural basis of asymmetry in the human immunodeficiency virus type 1
reverse transcriptase heterodimer.
DT 9410
AU Wang J; Smerdon SJ; Jager J; Kohlstaedt LA; Rice PA; Friedman JM; Steitz
TA; Department of Molecular Biophysics and Biochemistry, Howard; Hughes
Medical Institute, Yale University New Haven, CT; 06520-8114.
SO Proc Natl Acad Sci U S A. 1994 Jul 19;91(15):7242-6. Unique Identifier :
AIDSLINE MED/94316671
AB The reverse transcriptase from human immunodeficiency virus type 1 is a
heterodimer consisting of one 66-kDa and one 51-kDa subunit. The p66
subunit contains both a polymerase and an RNase H domain; proteolytic
cleavage of p66 removes the RNase H domain to yield the p51 subunit.
Although the polymerase domain of p66 folds into an open, extended
structure containing a large active-site cleft, that of p51 is closed
and compact. The connection subdomain, which lies between the polymerase
and RNase H active sites in p66, plays a central role in the formation
of the reverse transcriptase heterodimer. Extensive and very different
intra- and intersubunit contacts are made by the connection subdomains
of each of the subunits. Together, contacts between the two connection
domains constitute approximately one-third of the total contacts between
subunits of the heterodimer. Conversion of an open p66 polymerase domain
structure to a closed p51-like structure results in a reduction in
solvent-accessible surface area by 1600 A2 and the burying of an
extensive hydrophobic surface. Thus, the monomeric forms of both p66 and
p51 are proposed to have the same closed structure as seen in the p51
subunit of the heterodimer. The free energy required to convert p66 from
a closed p51-like structure to the observed open p66 polymerase domain
structure is generated by the burying of a large, predominantly
hydrophobic surface area upon formation of the heterodimer. It is likely
that the only kind of dimer that can form is an asymmetric one like that
seen in the heterodimer structure, since one dimer interaction surface
exists only in p51 and the other only in p66. We suggest that both p51
and p66 form asymmetric homodimers that are assembled from one subunit
that has assumed the open conformation and one that has the closed
structure.
DE Antibodies, Viral/CHEMISTRY DNA/CHEMISTRY HIV-1/*ENZYMOLOGY Models,
Molecular Protein Conformation Protein Folding Pyridines/PHARMACOLOGY
Reverse Transcriptase/ANTAGONISTS & INHIB/*CHEMISTRY/METABOLISM
Support, U.S. Gov't, P.H.S. JOURNAL ARTICLE
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).