5 research outputs found
Structure of a Monomeric Mutant of the HIV-1 Capsid Protein
The capsid protein (CA) of HIV-1 plays a significant
role in the
assembly of the immature virion and is the critical building block
of its mature capsid. Thus, there has been significant interest in
the CA protein as a target in the design of inhibitors of early and
late stage events in the HIV-1 replication cycle. However, because
of its inherent flexibility from the interdomain linker and the monomer–dimer
equilibrium in solution, the HIV-1 wild-type CA monomer has defied
structural determinations by X-ray crystallography and nuclear magnetic
resonance spectroscopy. Here we report the detailed solution structure
of full-length HIV-1 CA using a monomeric mutant that, though noninfective,
preserves many of the critical properties of the wild-type protein.
The structure shows independently folded N-terminal (NTD) and C-terminal
domains (CTD) joined by a flexible linker. The CTD shows some differences
from that of the dimeric wild-type CTD structures. This study provides
insights into the molecular mechanism of the wild-type CA dimerization
critical for capsid assembly. The monomeric mutant allows investigation
of interactions of CA with human cellular proteins exploited by HIV-1,
directly in solution without the complications associated with the
monomer–dimer equilibrium of the wild-type protein. This structure
also permits the design of inhibitors directed at a novel target,
viz., interdomain flexibility, as well as inhibitors that target multiple
interdomain interactions critical for assembly and interactions of
CA with host cellular proteins that play significant roles within
the replication cycle of HIV-1
1H, 15N, and 13C resonance assignments for a monomeric mutant of the HIV-1 capsid protein
Autoimmune Hypophysitis of SJL Mice: Clinical Insights from a New Animal Model
Autoimmune hypophysitis (AH) is a rare but increasingly recognized disease of the pituitary gland. Its autoantigens are unknown, and the management is difficult because it is often misdiagnosed as a nonsecreting adenoma. By immunizing female SJL/J mice with mouse pituitary extracts, we established a new mouse model of experimental AH. Immunized mice developed severe lymphocytic infiltration in the anterior pituitary that closely mimicked the human pathology. In the early phase of experimental AH, the pituitary enlarged, consistent with the compression symptoms reported by hypophysitis patients at presentation. In the florid phase, adrenal insufficiency and pituitary antibodies developed, in strong correlation with the pituitary pathology. In the late phase, hypothyroidism ensued, and the pituitary gland became atrophic. Using immune sera as probes in a two-dimensional immunoblotting screen followed by mass spectrometry, we identified several proteins that could function as pituitary autoantigens. These findings provide new insights into the pathogenesis of AH, and establish a platform for developing novel diagnostic biomarkers and therapeutics