Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have constructed human immunodeficiency virus (HIV) gag mutants by increasing the matrix protein (MA) sequences via tandemly repeated duplication of the central 107-MA codons. Instead of a total of 132 amino acid residues for the wild-type MA, the resultant mutants designated as MA2, MA3, and MA4 contained a total of 242, 352, and 462 codons in the MA domains, respectively. Analysis indicated that the addition of 110 or 220 amino acid residues to the MA did not significantly affect the assembly, release, and processing of particles; however, particle production was markedly reduced when another copy of 110 residues was added to the MA. Subcellular fractionation analysis suggested that the MA tandem repeat mutations enhanced the Gag membrane affinity, in a manner which correlated with the copy number of MA sequences. The effects of enhanced membrane affinity were substantially reduced when sequences downstream of the capsid (CA) domain were deleted. Sucrose density gradient fractionation analysis showed that particles produced by the large insertion mutants possessed wild-type (wt) HIV particle density. Truncation of sequences downstream of the nucleocapsid (NC) domains of the mutants did not influence the budding of particles. In contrast, particle budding was severely impaired when sequences downstream of the CA domain were truncated. Particle densities for the large Gag proteins, which were truncated at the C-terminus of CA, were about 1.12-1.14 g/ml lower than that for wt. Our results suggest that the HIV MA domain could adopt insertions of large protein sequences, and strongly support the proposal that the NC and p2 domains play a crucial role in the process of correct Gag protein packing.
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PMID:Assembly and release of human immunodeficiency virus type 1 Gag proteins containing tandem repeats of the matrix protein coding sequences in the matrix domain. 1111 3

A simple and efficient method for expression in Escherichia coli and purification of matrix protein, p17, of human immunodeficiency virus type 1 (HIV-1) of both B- and C-subtypes is described. DNA sequences encoding p17 of B- and C-subtype were cloned from respective gag sequences. The gag sequences were obtained by PCR amplification using DNA extracted from peripheral blood lymphocytes of an HIV-1 infected patient from India. A T7-promoter-based expression system was optimized for expression of p17 in soluble form. p17 (B- and C-subtype) was purified to near homogeneity using conventional chromatographic techniques. Purification of p17 (C-subtype) is described for the first time with yield of 7.7 mg from a 1-liter culture. The yield of p17 (B-subtype) is 14.7 mg from a 1-liter culture, which is severalfold better than that reported earlier. N-terminal sequencing and CD spectra of the purified proteins, p17B and p17C, show that the proteins are properly processed and well-folded. The immunoreactivity of both types of p17 to sera from HIV-infected individuals is comparable.
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PMID:Gag-derived proteins of HIV-1 isolates from Indian patients: cloning, expression, and purification of p17 of B- and C-subtypes. 1128 11

The human immunodeficiency virus type-1 matrix protein (HIV-1 MA) is a multifunctional structural protein synthesized as part of the Pr55 gag polyprotein. We have used in vitro genetic selection to identify an RNA consensus sequence that specifically interacts with MA (Kd = 5 x 10(-7) M). This 13-nt MA binding consensus sequence bears a high degree of homology (77%) to a region (nt 1433-1446) within the POL open reading frame of the HIV-1 genome (consensus sequence from 38 HIV-1 strains). Chemical interference experiments identified the nucleotides within the MA binding consensus sequence involved in direct contact with MA. We further demonstrate that this RNA-protein interaction is mediated through a stretch of basic amino acids within MA. Mutations that disrupt the interaction between MA and its RNA binding site within the HIV-1 genome resulted in a measurable decrease in viral replication.
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PMID:Sequence-specific interaction between HIV-1 matrix protein and viral genomic RNA revealed by in vitro genetic selection. 1134 36

We have previously demonstrated by Gag polyprotein budding assays that the Gag p9 protein of equine infectious anemia virus (EIAV) utilizes a unique YPDL motif as a late assembly domain (L domain) to facilitate release of the budding virus particle from the host cell plasma membrane (B. A. Puffer, L. J. Parent, J. W. Wills, and R. C. Montelaro, J. Virol. 71:6541-6546, 1997). To characterize in more detail the role of the YPDL L domain in the EIAV life cycle, we have examined the replication properties of a series of EIAV proviral mutants in which the parental YPDL L domain was replaced by a human immunodeficiency virus type 1 (HIV-1) PTAP or Rous sarcoma virus (RSV) PPPY L domain in the p9 protein or by proviruses in which the parental YPDL or HIV-1 PTAP L domain was inserted in the viral matrix protein. The replication properties of these L-domain variants were examined with respect to Gag protein expression and processing, virus particle production, and virus infectivity. The data from these experiments indicate that (i) the YPDL L domain of p9 is required for replication competence (assembly and infectivity) in equine cell cultures, including the natural target equine macrophages; (ii) all of the functions of the YPDL L domain in the EIAV life cycle can be replaced by replacement of the parental YPDL sequence in p9 with the PTAP L-domain segment of HIV-1 p6 or the PPPY L domain of RSV p2b; and (iii) the assembly, but not infectivity, functions of the EIAV proviral YPDL substitution mutants can be partially rescued by inclusions of YPDL and PTAP L-domain sequences in the C-terminal region of the EIAV MA protein. Taken together, these data demonstrate that the EIAV YPDL L domain mediates distinct functions in viral budding and infectivity and that the HIV-1 PTAP and RSV PPPY L domains can effectively facilitate these dual replication functions in the context of the p9 protein. In light of the fact that YPDL, PTAP, and PPPY domains evidently have distinct characteristic binding specificities, these observations may indicate different portals into common cellular processes that mediate EIAV budding and infectivity, respectively.
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PMID:Functional replacement and positional dependence of homologous and heterologous L domains in equine infectious anemia virus replication. 1179 51

The Gag polyprotein is key to the budding of retroviruses from host cells and is cleaved upon virion maturation, the N-terminal membrane-binding domain forming the matrix protein (MA). The 2.8-A resolution crystal structure of MA of equine infectious anemia virus (EIAV), a lentivirus, reveals that, despite showing no sequence similarity, more than half of the molecule can be superimposed on the MAs of human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV). However, unlike the structures formed by HIV-1 and SIV MAs, the oligomerization state observed is not trimeric. We discuss the potential of this molecule for membrane binding in the light of conformational differences between EIAV MA and HIV or SIV MA.
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PMID:Structure of equine infectious anemia virus matrix protein. 1179 82

We have studied the organization of mature infectious Rous sarcoma virus (RSV), suspended in vitreous ice, using transmission electron microscopy. The enveloped virions are spherical in shape, have a mean diameter of 127 nm, and vary significantly in size. Image processing reveals the presence of the viral matrix protein underlying the lipid bilayer and the viral envelope proteins external to the lipid bilayer. In the interior of the virus, the characteristic mature retroviral core is clearly imaged. In contrast to lentiviruses, such as human immunodeficiency virus, the core of RSV is essentially isometric. The capsid, or external shell of the core, has a faceted, almost polygonal appearance in electron micrographs, but many capsids also exhibit continuous surface curvature. Cores are not uniform in size or shape. Serrations observed along the projected faces of the core suggest a repetitive molecular structure. Some isolated cores were observed in the sample, confirming that cores are at least transiently stable in the absence of the viral envelope. Using an approach grounded in geometric probability, we estimate the size of the viral core from the projection data. We show that the size of the core is not tightly controlled and that core size and virion size are positively correlated. From estimates of RNA packing density we conclude that either the RNA within the core is loosely packed or, more probably, that it does not fill the core.
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PMID:The organization of mature Rous sarcoma virus as studied by cryoelectron microscopy. 1185 8

The human immunodeficiency virus type 1 transmembrane glycoprotein (TM) is efficiently endocytosed in a clathrin-dependent manner. Internalization is mediated by a tyrosine-containing motif within the cytoplasmic domain, and replacement of the cytoplasmic tyrosine by cysteine or phenylalanine increased expression of mutant glycoprotein on the surface of transfected cells by as much as 2.5-fold. Because interactions between the cytoplasmic domain of Env and the matrix protein (MA) have been suggested to mediate incorporation of Env in virus particles, we examined whether perturbation of endocytosis would alter incorporation. Proviruses were constructed to contain the wild-type or mutant Env in conjunction with point mutations in MA that had previously been shown to block Env incorporation. These constructs were used to evaluate the effect of glycoprotein endocytosis on incorporation into virus particles and to test the necessity for a specific interaction between Env and MA to mediate incorporation. Viruses produced from transfected 293T cells were used to infect various cell lines, including MAGI, H9, and CEMx174. Viruses encoding both a disrupted endocytosis motif signal and mutations within MA were significantly more infectious in MAGI cells than their counterparts encoding a mutant MA and wild-type Env. This complementation of infectivity for the MA incorporation mutant viruses was not due to increased glycoprotein incorporation into particles but instead reflected an enhanced fusogenicity of the mutated Env proteins. Our findings further support the concept that a specific interaction between the long cytoplasmic domain of TM and MA is required for efficient incorporation of Env into assembling virions. Alteration of the endocytosis signal of Env, and the resulting increase in cell surface glycoprotein, has no effect on incorporation despite demonstrable effects on fusion, virus entry, and infectivity.
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PMID:Mutation of the dominant endocytosis motif in human immunodeficiency virus type 1 gp41 can complement matrix mutations without increasing Env incorporation. 1188 59

In the present work we have constructed a series of backbone cyclic peptides, which differed in the amino acid residues located at the C-terminal position of the previously described BCvir peptide (A. Friedler, N. Zakai, O. Karni, Y.C. Broder, L. Baraz, M. Kotler, A. Loyter, C. Gilon, Biochemistry 37 (1998)). BCvir is a cyclic peptide, derived from the nuclear localization signal (NLS) of the human immunodeficiency virus type 1 matrix protein. The majority of the cyclic peptides described here inhibited nuclear import in vitro. The most potent inhibitors were those bearing bulky hydrophobic amino acids such as Leu, Phe or Nal (naphthyl Ala) at the C-terminus. On the other hand, peptides bearing polar amino acid residues such as Asn, Cys or a reduced amide bond were not inhibitory. The present studies demonstrate the importance of a bulky hydrophobic C-terminal side chain and an exocyclic amide bond preceding it, to the inhibitory activity of the NLS-derived BC peptides. Being only inhibitory, these BC peptides resemble classic receptor antagonists.
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PMID:Inhibition of nuclear import by backbone cyclic peptidomimetics derived from the HIV-1 MA NLS sequence. 1190 19

Bovine immunodeficiency virus (BIV) and Jembrana disease virus (JDV) are closely related bovine lentiviruses that are difficult to distinguish by presently available diagnostic methods. Recently, in our laboratory, a monoclonal antibody (MAb; MAb 10H1) against the BIV Gag protein identified a differential epitope, located at the 6.4-kDa N terminus of a 29-kDa Gag capsid protein, which was absent in JDV. To define the essential amino acids of the epitope, a series of primers within the 163 bp of DNA corresponding to the 6.4-kDa protein were designed. The full-length 163-bp DNA fragment and the smaller DNA fragments with deletions were amplified by PCR and then cloned into pQE32 vectors for protein expression studies. The expressed proteins were analyzed with MAb 10H1 by Western blotting. The differential epitope has been narrowed to a 26-amino-acid region (R121 to R146), which includes 6 residues of p16(MA) (where MA represents the matrix protein) and 20 residues of p2L. A synthetic peptide corresponding to the putative 26-amino-acid epitope blocked MAb 10H1 binding to the expressed peptide. These experiments revealed that the epitope spans the cleavage site between p16(MA) and p2L and presumably will be valuable in distinguishing the two viruses.
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PMID:Unique epitope of bovine immunodeficiency virus gag protein spans the cleavage site between p16(MA) and p2L. 1241 61

In this issue, McDonald et al. describe the itinerary of the incoming human immunodeficiency virus (HIV) during its travels to the host nucleus. They show that subviral particles tagged with the green fluorescent protein (GFP) are propelled along microtubules (MTs) by minus-end-directed and presumably plus-end-directed MT motors. The tracked particles correspond to functional units, since they no longer include a viral envelope, but do include viral matrix protein, Vpr, capsid protein, and reverse transcription activity.
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PMID:Unchain my heart, baby let me go--the entry and intracellular transport of HIV. 1241 76


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