scholarly journals Two Regions within the Amino-Terminal Half of APOBEC3G Cooperate To Determine Cytoplasmic Localization

2008 ◽  
Vol 82 (19) ◽  
pp. 9591-9599 ◽  
Author(s):  
Mark D. Stenglein ◽  
Hiroshi Matsuo ◽  
Reuben S. Harris
Keyword(s):  
Amino Acid ◽  
Subcellular Localization ◽  
Protein A ◽  
Antiviral Effect ◽  
Full Length ◽  
Single Amino Acid ◽  
Cytoplasmic Localization ◽  
Amino Terminal ◽  
Immunodeficiency Virus ◽  
Viral Cdna

ABSTRACT APOBEC3G limits the replication of human immunodeficiency virus type 1, other retroviruses, and retrotransposons. It localizes predominantly to the cytoplasm of cells, which is consistent with a model wherein cytosolic APOBEC3G packages into assembling virions, where it exerts its antiviral effect by deaminating viral cDNA cytosines during reverse transcription. To define the domains of APOBEC3G that determine cytoplasmic localization, comparisons were made with APOBEC3B, which is predominantly nuclear. APOBEC3G/APOBEC3B chimeric proteins mapped a primary subcellular localization determinant to a region within the first 60 residues of each protein. A panel of 25 APOBEC3G mutants, each with a residue replaced by the corresponding amino acid of APOBEC3B, revealed that several positions within this region were particularly important, with Y19D showing the largest effect. The mislocalization phenotype of these mutants was only apparent in the context of the amino-terminal half of APOBEC3G and not the full-length protein, suggesting the existence of an additional localization determinant. Indeed, a panel of five single amino acid substitutions within the region from amino acids 113 to 128 had little effect by themselves but, in combination with Y19D, two substitutions—F126S and W127A—caused full-length APOBEC3G to redistribute throughout the cell. The critical localization-determining residues were predicted to cluster on a common solvent-exposed surface, suggesting a model in which these two regions of APOBEC3G combine to mediate an intermolecular interaction that controls subcellular localization.

scholarly journals Unusual Polymorphisms in Human Immunodeficiency Virus Type 1 Associated with Nonprogressive Infection

2000 ◽  
Vol 74 (9) ◽  
pp. 4361-4376 ◽  
Author(s):  
Louis Alexander ◽  
Emma Weiskopf ◽  
Thomas C. Greenough ◽  
Nathan C. Gaddis ◽  
Marcy R. Auerbach ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Transmembrane Protein ◽  
Full Length ◽  
Single Amino Acid ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Factors accounting for long-term nonprogression may include infection with an attenuated strain of human immunodeficiency virus type 1 (HIV-1), genetic polymorphisms in the host, and virus-specific immune responses. In this study, we examined eight individuals with nonprogressing or slowly progressing HIV-1 infection, none of whom were homozygous for host-specific polymorphisms (CCR5-Δ32, CCR2-64I, andSDF-1-3′A) which have been associated with slower disease progression. HIV-1 was recovered from seven of the eight, and recovered virus was used for sequencing the full-length HIV-1 genome; full-length HIV-1 genome sequences from the eighth were determined following amplification of viral sequences directly from peripheral blood mononuclear cells (PBMC). Longitudinal studies of one individual with HIV-1 that consistently exhibited a slow/low growth phenotype revealed a single amino acid deletion in a conserved region of the gp41 transmembrane protein that was not seen in any of 131 envelope sequences in the Los Alamos HIV-1 sequence database. Genetic analysis also revealed that five of the eight individuals harbored HIV-1 with unusual 1- or 2-amino-acid deletions in the Gag sequence compared to subgroup B Gag consensus sequences. These deletions in Gag have either never been observed previously or are extremely rare in the database. Three individuals had deletions in Nef, and one had a 4-amino-acid insertion in Vpu. The unusual polymorphisms in Gag, Env, and Nef described here were also found in stored PBMC samples taken 3 to 11 years prior to, or in one case 4 years subsequent to, the time of sampling for the original sequencing. In all, seven of the eight individuals exhibited one or more unusual polymorphisms; a total of 13 unusual polymorphisms were documented in these seven individuals. These polymorphisms may have been present from the time of initial infection or may have appeared in response to immune surveillance or other selective pressures. Our results indicate that unusual, difficult-to-revert polymorphisms in HIV-1 can be found associated with slow progression or nonprogression in a majority of such cases.

scholarly journals N-Terminal Acetyltransferase Naa40p Whereabouts Put into N-Terminal Proteoform Perspective

2021 ◽  
Vol 22 (7) ◽  
pp. 3690
Author(s):  
Veronique Jonckheere ◽  
Petra Van Damme
Keyword(s):  
Amino Acid ◽  
Subcellular Localization ◽  
Nuclear Import ◽  
Ribosome Biogenesis ◽  
Regulatory Protein ◽  
Ectopic Expression ◽  
Cytoplasmic Localization ◽  
Histone H2a ◽  
Histone H4 ◽  
Nucleolar Proteins

The evolutionary conserved N-alpha acetyltransferase Naa40p is among the most selective N-terminal acetyltransferases (NATs) identified to date. Here we identified a conserved N-terminally truncated Naa40p proteoform named Naa40p25 or short Naa40p (Naa40S). Intriguingly, although upon ectopic expression in yeast, both Naa40p proteoforms were capable of restoring N-terminal acetylation of the characterized yeast histone H2A Naa40p substrate, the Naa40p histone H4 substrate remained N-terminally free in human haploid cells specifically deleted for canonical Naa40p27 or 237 amino acid long Naa40p (Naa40L), but expressing Naa40S. Interestingly, human Naa40L and Naa40S displayed differential expression and subcellular localization patterns by exhibiting a principal nuclear and cytoplasmic localization, respectively. Furthermore, Naa40L was shown to be N-terminally myristoylated and to interact with N-myristoyltransferase 1 (NMT1), implicating NMT1 in steering Naa40L nuclear import. Differential interactomics data obtained by biotin-dependent proximity labeling (BioID) further hints to context-dependent roles of Naa40p proteoforms. More specifically, with Naa40S representing the main co-translationally acting actor, the interactome of Naa40L was enriched for nucleolar proteins implicated in ribosome biogenesis and the assembly of ribonucleoprotein particles, overall indicating a proteoform-specific segregation of previously reported Naa40p activities. Finally, the yeast histone variant H2A.Z and the transcriptionally regulatory protein Lge1 were identified as novel Naa40p substrates, expanding the restricted substrate repertoire of Naa40p with two additional members and further confirming Lge1 as being the first redundant yNatA and yNatD substrate identified to date.

scholarly journals Sensitivity of human immunodeficiency virus to bicyclam derivatives is influenced by the three-dimensional structure of gp120.

1997 ◽  
Vol 41 (12) ◽  
pp. 2616-2620 ◽  
Author(s):  
K De Vreese ◽  
I Van Nerum ◽  
K Vermeire ◽  
J Anné ◽  
E De Clercq
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Single Amino Acid ◽  
Resistance Pattern ◽  
V3 Loop ◽  
Resistant Virus ◽  
Wild Type ◽  
Immunodeficiency Virus ◽  
Resistant Strains ◽  
Anti Hiv

The bicyclams are a new class of anti-human immunodeficiency virus (anti-HIV) compounds targeted at viral entry. From marker rescue experiments, it appears that the envelope gp120 glycoprotein plays an important role in the anti-HIV activity of the bicyclams. Bicyclam-resistant strains contain a number of amino acid changes scattered over the V2 to V5 region of gp120. Experiments aimed at estimating the relative importance of particular amino acid changes with regard to the overall resistance pattern are described. The sequences of some partially bicyclam-resistant virus strains, obtained during the resistance development process, were analyzed, and the corresponding 50% effective concentrations were determined. Selected mutations observed in bicyclam-resistant strains were introduced in the wild-type background by site-directed mutagenesis. In addition, some amino acids were back-mutated to their wild-type counterparts in an otherwise JM3100-resistant strain. The sensitivities of these mutant viruses to bicyclams were determined. Construction of chimeric viruses, carrying the V3 loop of JM3100-resistant virus in a wild-type HIV type 1 HXB2 background, enabled us to investigate the importance of the mutations in the V3 loop of JM3100-resistant virus. From the results described in the report, it can be concluded that single amino acid substitutions do not influence the observed resistance to JM3100. Also, the mutations in the V3 loop are not sufficient to engender even a partially resistant phenotype. We postulate that the overall conformation of gp120 determines the degree of sensitivity or resistance of HIV strains to bicyclams.

scholarly journals Opposing Effects of Inhibiting Cap Addition and Cap Methylation on Polyadenylation during Vesicular Stomatitis Virus mRNA Synthesis

2008 ◽  
Vol 83 (4) ◽  
pp. 1930-1940 ◽  
Author(s):  
Jianrong Li ◽  
Amal Rahmeh ◽  
Vesna Brusic ◽  
Sean P. J. Whelan
Keyword(s):  
Amino Acid ◽  
Vesicular Stomatitis Virus ◽  
Rna Synthesis ◽  
Full Length ◽  
Single Amino Acid ◽  
Mrna Synthesis ◽  
L Protein ◽  
Vesicular Stomatitis ◽  
Opposing Effects ◽  
Gene Junction

ABSTRACT The multifunctional large (L) polymerase protein of vesicular stomatitis virus (VSV) contains enzymatic activities essential for RNA synthesis, including mRNA cap addition and polyadenylation. We previously mapped amino acid residues G1154, T1157, H1227, and R1228, present within conserved region V (CRV) of L, as essential for mRNA cap addition. Here we show that alanine substitutions to these residues also affect 3′-end formation. Specifically, the cap-defective polymerases produced truncated transcripts that contained A-rich sequences at their 3′ termini and predominantly terminated within the first 500 nucleotides (nt) of the N gene. To examine how the cap-defective polymerases respond to an authentic VSV termination and reinitiation signal present at each gene junction, we reconstituted RNA synthesis using templates that contained genes inserted (I) at the leader-N gene junction. The I genes ranged in size from 382 to 1,098 nt and were typically transcribed into full-length uncapped transcripts. In addition to lacking a cap structure, the full-length I transcripts synthesized by the cap-defective polymerases lacked an authentic polyadenylate tail and instead contained 0 to 24 A residues. Moreover, the cap-defective polymerases were also unable to copy efficiently the downstream gene. Thus, single amino acid substitutions in CRV of L protein that inhibit cap addition also inhibit polyadenylation and sequential transcription of the genome. In contrast, an amino acid substitution, K1651A, in CRVI of L protein that completely inhibits cap methylation results in the hyperpolyadenylation of mRNA. This work reveals that inhibiting cap addition and cap methylation have opposing effects on polyadenylation during VSV mRNA synthesis and provides evidence in support of a link between correct 5′ cap formation and 3′ polyadenylation.

scholarly journals Two monomers of yeast transcription factor ADR1 bind a palindromic sequence symmetrically to activate ADH2 expression.

1991 ◽  
Vol 11 (3) ◽  
pp. 1566-1577 ◽  
Author(s):  
S K Thukral ◽  
A Eisen ◽  
E T Young
Keyword(s):  
Transcription Factor ◽  
Amino Acid ◽  
Dna Binding ◽  
Dimethyl Sulfate ◽  
Binding Activity ◽  
Single Amino Acid ◽  
Minor Effect ◽  
Palindromic Sequence ◽  
Amino Terminal ◽  
Dna Binding Activity

ADR1 is a transcription factor from Saccharomyces cerevisiae that regulates ADH2 expression through a 22-bp palindromic sequence (UAS1). Size fractionation studies revealed that full-length ADR1 and a truncated ADR1 protein containing the first 229 amino acids, which has the complete DNA-binding domain, ADR1:17-229, exist as monomers in solution. However, two complexes were formed with target DNA-binding sites. UV-cross-linking studies suggested that these two complexes represent one and two molecules of ADR1 bound to DNA. Studies of ADR1 complexes formed with wild-type UAS1, asymmetrically altered UAS1, and one half of UAS1 showed that ADR1 can bind to one half of UAS1 and gives rise to a complex containing one molecule of ADR1. Dimethyl sulfate interference studies were consistent with this interpretation and in addition indicated that purine contact sites in each half of UAS1 were identical. Increasing the distance between the two halves of UAS1 had at most a minor effect of the thermodynamics of formation of the two complexes. These data are more consistent with ADR1 binding as two independent monomers, one to each half of UAS1. However, binding of two ADR1 monomers at UAS1 is apparently essential for transactivation in vivo. Further, we have identified a stretch of 18 amino acid residues amino terminal to the zinc two-finger domains of ADR1 which is essential for DNA-binding activity. Single amino acid substitutions of residues in this region resulted in severely reduced DNA-binding activity.

scholarly journals Coreceptor Tropism Can Be Influenced by Amino Acid Substitutions in the gp41 Transmembrane Subunit of Human Immunodeficiency Virus Type 1 Envelope Protein

2008 ◽  
Vol 82 (11) ◽  
pp. 5584-5593 ◽  
Author(s):  
Wei Huang ◽  
Jonathan Toma ◽  
Signe Fransen ◽  
Eric Stawiski ◽  
Jacqueline D. Reeves ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Envelope Protein ◽  
Variable Region ◽  
Single Amino Acid ◽  
Coreceptor Tropism ◽  
Immunodeficiency Virus

ABSTRACT Many studies have demonstrated that the third variable region (V3) of the human immunodeficiency virus type 1 (HIV-1) envelope protein (Env) is a major determinant of coreceptor tropism. Other regions in the surface gp120 subunit of Env can modulate coreceptor tropism in a manner that is not fully understood. In this study, we evaluated the effect of env determinants outside of V3 on coreceptor usage through the analysis of (i) patient-derived env clones that differ in coreceptor tropism, (ii) chimeric env sequences, and (iii) site-directed mutants. The introduction of distinct V3 sequences from CXCR4-using clones into an R5-tropic env backbone conferred the inefficient use of CXCR4 in some but not all cases. Conversely, in many cases, X4- and dual-tropic env backbones containing the V3 sequences of R5-tropic clones retained the ability to use CXCR4, suggesting that sequences outside of the V3 regions of these CXCR4-using clones were responsible for CXCR4 use. The determinants of CXCR4 use in a set of dual-tropic env sequences with V3 sequences identical to those of R5-tropic clones mapped to the gp41 transmembrane (TM) subunit. In one case, a single-amino-acid substitution in the fusion peptide of TM was able to confer CXCR4 use; however, TM substitutions associated with CXCR4 use varied among different env sequences. These results demonstrate that sequences in TM can modulate coreceptor specificity and that env sequences other than that of V3 may facilitate efficient CXCR4-mediated entry. We hypothesize that the latter plays an important role in the transition from CCR5 to CXCR4 coreceptor use.

scholarly journals A Single Amino Acid Substitution in a Segment of the CA Protein within Gag That Has Similarity to Human Immunodeficiency Virus Type 1 Blocks Infectivity of a Human Endogenous Retrovirus K Provirus in the Human Genome

2008 ◽  
Vol 83 (2) ◽  
pp. 1105-1114 ◽  
Author(s):  
David J. Heslin ◽  
Pablo Murcia ◽  
Frederick Arnaud ◽  
Koenraad Van Doorslaer ◽  
Massimo Palmarini ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Human Genome ◽  
Particle Production ◽  
Endogenous Retrovirus ◽  
Single Amino Acid ◽  
Human Endogenous Retrovirus ◽  
C Terminus ◽  
Immunodeficiency Virus

ABSTRACT Human endogenous retrovirus K (HERV-K) is the most intact retrovirus in the human genome. However, no single HERV-K provirus in the human genome today appears to be infectious. Since the Gag protein is the central component for the production of retrovirus particles, we investigated the abilities of Gag from two HERV-K proviruses to support production of virus-like particles and viral infectivity. HERV-K113 has full-length open reading frames for all viral proteins, while HERV-K101 has a full-length gag open reading frame and is expressed in human male germ cell tumors. The Gag of HERV-K101 allowed production of viral particles and infectivity, although at lower levels than observed with a consensus sequence Gag. Thus, including HERV-K109, at least two HERV-K proviruses in human genome today have functional Gag proteins. In contrast, HERV-K113 Gag supported only very low levels of particle production, and no infectivity was detectable due to a single amino acid substitution (I516M) near the extreme C terminus of the CA protein within Gag. The sequence of this portion of HERV-K CA showed similarities to that of human immunodeficiency virus type 1 and other primate immunodeficiency viruses. The extreme C terminus of CA may be a general determinant of retrovirus particle production. In addition, precise mapping of the defects in HERV-K proviruses as was done here identifies the key polymorphisms that need to be analyzed to assess the possible existence of infectious HERV-K alleles within the human population.

A Novel Human Actin-Binding Protein Homologue That Binds to Platelet Glycoprotein Ib

Blood ◽  
1998 ◽  
Vol 92 (4) ◽  
pp. 1268-1276 ◽  
Author(s):  
Wen-feng Xu ◽  
Zhi-wei Xie ◽  
Dominic W. Chung ◽  
Earl W. Davie
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Binding Protein ◽  
Full Length ◽  
Actin Binding ◽  
Intracellular Domain ◽  
Platelet Surface ◽  
Full Length Cdna ◽  
Actin Binding Protein ◽  
Amino Terminal

Glycoprotein (GP)Ib-IX-V is one of the major transmembrane complexes present on the platelet surface. Its extracellular domain binds von Willebrand factor (vWF) and thrombin, while its intracellular domain associates tightly with the cytoskeleton through the actin-binding protein (ABP)-280, also known as filamin. In the present study, a full-length cDNA coding for a human ABP homologue has been cloned and sequenced. This protein was identified by the yeast two-hybrid screening procedure via its interaction with the intracellular domain of GPIb. Initially, a 1.3-kb partial cDNA was isolated from a megakaryocyte-like cell line (K562) cDNA library followed by a full-length cDNA of 9.4 kb that was identified in a human placenta library. The full-length cDNA encoded a protein of 2,578 amino acids with a calculated molecular weight of 276 kD (ABP-276). The amino terminal 248 amino acids contained an apparent actin binding domain followed by 24 tandem repeats each containing about 96 amino acids. The amino acid sequence of the protein shared a high degree of homology with human endothelial ABP-280 (70% identity) and chicken filamin (83% identity). However, the 32 amino acid Hinge I region in ABP-280 that contains a calpain cleavage site conferring flexibility on the molecule, was absent in the homologue. An isoform containing a 24 amino acid insertion with a unique sequence at the missing Hinge I region was also identified (ABP-278). This isoform resulted from alternative RNA splicing. ABP-276 and/or ABP-278 were present in all tissues examined, but the relative amount varied in that some tissue contained both forms, while other tissue contained predominately one or the other. © 1998 by The American Society of Hematology.

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