scholarly journals Differential Utilization of CD134 as a Functional Receptor by Diverse Strains of Feline Immunodeficiency Virus

2006 ◽  
Vol 80 (7) ◽  
pp. 3386-3394 ◽  
Author(s):  
Brian J. Willett ◽  
Elizabeth L. McMonagle ◽  
Susan Ridha ◽  
Margaret J. Hosie
Keyword(s):  
Amino Acids ◽  
Disease Progression ◽  
Feline Immunodeficiency Virus ◽  
Cell Tropism ◽  
Receptor Function ◽  
Rich Domain ◽  
Immunodeficiency Virus ◽  
Primary Determinant ◽  
Functional Receptor ◽  
Cysteine Rich Domain

ABSTRACT The feline homologue of CD134 (fCD134) is the primary binding receptor for feline immunodeficiency virus (FIV), targeting the virus preferentially to activated CD4+ helper T cells. However, with disease progression, the cell tropism of FIV broadens such that B cells and monocytes/macrophages become significant reservoirs of proviral DNA, suggesting that receptor utilization may alter with disease progression. We examined the receptor utilization of diverse strains of FIV and found that all strains tested utilized CD134 as the primary receptor. Using chimeric feline × human CD134 receptors, the primary determinant of receptor function was mapped to the first cysteine-rich domain (CRD1) of fCD134. For the PPR and B2542 strains, the replacement of CDR1 of fCD134 (amino acids 1 to 64) with human CD134 (hCD134) alone was sufficient to confer nearly optimal receptor function. However, evidence of differential utilization of CD134 was revealed, since strains GL8, CPGammer (CPG41), TM2, 0827, and NCSU1 required determinants in the region spanning amino acids 65 to 85, indicating that these strains may require a more stringent interaction for infection to proceed.

scholarly journals Mapping the Domains of CD134 as a Functional Receptor for Feline Immunodeficiency Virus

2006 ◽  
Vol 80 (15) ◽  
pp. 7744-7747 ◽  
Author(s):  
Brian J. Willett ◽  
Elizabeth L. McMonagle ◽  
Francesca Bonci ◽  
Mauro Pistello ◽  
Margaret J. Hosie
Keyword(s):  
Feline Immunodeficiency Virus ◽  
Helper T Cells ◽  
Amino Acid Substitutions ◽  
Receptor Function ◽  
Viral Receptor ◽  
Rich Domain ◽  
Critical Residue ◽  
Immunodeficiency Virus ◽  
Functional Receptor ◽  
Cysteine Rich Domain

ABSTRACT The feline homologue of CD134 is the primary binding receptor for feline immunodeficiency virus (FIV), targeting the virus preferentially to activated CD4+ helper T cells. However, strains of FIV differ in utilization of CD134; the prototypic strain PPR requires a minimal determinant in the first cysteine-rich domain (CRD1) of feline CD134 to confer near-optimal receptor function, while strains such as GL8 require additional determinants in the CD134 CRD2. We map this determinant to a loop in CRD2 governing the interaction between the receptor and its ligand; the amino acid substitutions S78N-S79Y-K80E restored full viral receptor activity to the CDR2 of human CD134 in the context of feline CD134, with tyrosine-79 appearing to be the critical residue for restoration of receptor function.

scholarly journals Frizzled BRET sensors based on bioorthogonal labeling of unnatural amino acids reveal WNT-induced dynamics of the cysteine-rich domain.

2021 ◽  
Author(s):  
Maria Kowalski-Jahn ◽  
Hannes Schihada ◽  
Ainoleena Turku ◽  
Thomas Huber ◽  
Thomas P. Sakmar ◽  
...  
Keyword(s):  
Amino Acids ◽  
Unnatural Amino Acids ◽  
Conformational Dynamics ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Receptor Activation ◽  
Membrane Receptors ◽  
Rich Domain ◽  
Linker Domain ◽  
Cysteine Rich Domain

Frizzleds (FZD1-10) comprise a class of G protein-coupled receptors containing an extracellular cysteine-rich domain (CRD) that binds lipoglycoproteins of the Wingless/Int-1 family (WNTs). Despite the prominent role of the WNT/FZD system in health and disease, our understanding of how WNT binding to the FZD CRD is translated into receptor activation and transmembrane signaling remains limited. Current hypotheses dispute the roles for conformational dynamics and the involvement of the linker domain connecting the CRD with the seven-helical transmembrane core of FZD. To clarify the mechanism of WNT binding to FZD and to elucidate how WNT/FZD complexes achieve signaling pathway specificity, we devised conformational FZD-CRD biosensors based on bioluminescence-resonance-energy-transfer (BRET). Using FZD engineered with N-terminal nanoluciferase and fluorescently-labeled unnatural amino acids in the linker domain and extracellular loop 3, we show that WNT-3A and WNT-5A induce similar CRD conformational rearrangements despite promoting distinct downstream signaling pathways, and that CRD dynamics are not required for WNT/β-catenin signaling. Thus, the novel FZD-CRD biosensors we report provide insights into the stepwise binding, activation and signaling processes in FZDs. The sensor design is broadly applicable to explore fundamental events in signal transduction mediated by other membrane receptors.

scholarly journals The Linker Domain of SNAP25 Acts as a Flexible Molecular Spacer to Ensure Efficient S-Acylation

2020 ◽  
Author(s):  
Christine Salaun ◽  
Jennifer Greaves ◽  
Nicholas C.O. Tomkinson ◽  
Luke H. Chamberlain
Keyword(s):  
Amino Acids ◽  
Binding Motif ◽  
Linear Motif ◽  
Linker Region ◽  
Rich Domain ◽  
Enzyme Substrate ◽  
Efficient Coupling ◽  
Affinity Interaction ◽  
Linker Domain ◽  
Cysteine Rich Domain

ABSTRACTS-Acylation of the SNARE protein SNAP25 is mediated by a subset of Golgi zDHHC enzymes, in particular zDHHC17. The ankyrin repeat (ANK) domain of this enzyme interacts with a short linear motif known as the zDHHC ANK binding motif (zDABM) in SNAP25 (112-VVASQP-117), which is downstream of the S-acylated cysteine-rich domain (85-CGLCVCPC-92). In this study, we have investigated the importance of the flexible linker (amino acids 93-111; referred to as the “mini-linker” region) that separates the zDABM and S-acylated cysteines. Shortening the mini-linker had no effect of zDHHC17 interaction but blocked S-acylation. Insertion of additional flexible glycine-serine repeats had no effect on S-acylation, whereas extended and rigid alanine-proline repeats perturbed this process. Indeed, a SNAP25 mutant in which the mini-linker region was substituted with a flexible glycine-serine linker of the same length underwent efficient S-acylation. Furthermore, this mutant displayed the same intracellular localisation as wild-type SNAP25, showing that the sequence of the mini-linker is not important in this context. By using the results of previous peptide array experiments, we generated a SNAP25 mutant predicted to have a higher affinity zDABM, and this mutant showed enhanced interaction with zDHHC17 in cells. Interestingly, this mutant was S-acylated with reduced efficiency, implying that a lower affinity interaction of the SNAP25 zDABM with zDHHC17 is optimal for S-acylation efficiency. Overall, the results of this study show that amino acids 93-111 in SNAP25 act as a flexible molecular spacer to ensure efficient coupling of enzyme-substrate interaction and S-acylation.

scholarly journals Differential Cell Tropism of Feline Immunodeficiency Virus Molecular Clones In Vivo

1999 ◽  
Vol 73 (4) ◽  
pp. 2596-2603 ◽  
Author(s):  
Gregg A. Dean ◽  
Sunee Himathongkham ◽  
Ellen E. Sparger
Keyword(s):  
Feline Immunodeficiency Virus ◽  
Mononuclear Cells ◽  
Lymphocyte Subsets ◽  
Cell Tropism ◽  
Replication Efficiency ◽  
Proviral Dna ◽  
Immunodeficiency Virus ◽  
Differential Cell

ABSTRACT Independent studies have demonstrated different cell tropisms for molecular clones of feline immunodeficiency virus (FIV). In this report, we examined three clones, FIV-pF34, FIV-14, and FIV-pPPR, for replication in Crandell feline kidney (CrFK) cells, feline peripheral blood mononuclear cells (PBMC), and feline macrophage cultures. Importantly, cell tropism for these three clones was also examined in vivo. FIV-pF34 replication was efficient in CrFK cells but severely restricted in PBMC, whereas replication of FIV-pPPR was vigorous in PBMC but severely restricted in CrFK cells. FIV-14 replication was productive in both CrFK cells and PBMC. Interestingly, all three molecular clones replicated with similar efficiencies in primary feline monocyte-derived macrophages. In vivo, FIV-pF34 proved least efficient for establishing persistent infection, and proviral DNA when detectable, was localized predominately to nonlymphoid cell populations (macrophages). FIV-pPPR proved most efficient for induction of a persistent viremia in vivo, and proviral DNA was localized predominately in CD4+ and CD8+ lymphocyte subsets. FIV-14 inoculation of cats resulted in an infection characterized by seroconversion and localization of proviral DNA in CD4+ lymphocytes only. Results of this study on diverse FIV molecular clones revealed that in vitro replication efficiency of an FIV isolate in PBMC directly correlated with replication efficiency in vivo, whereas proficiency for replication in macrophages in vitro was not predictive for replication potential in vivo. Also, infection of both CD4+ and CD8+ lymphocyte subsets was associated with higher virus load in vivo. Results of the studies on these three FIV clones, which exhibited differential cell tropism, indicated a correlation between in vitro and in vivo cell tropism and virus replication.

scholarly journals Experimental Mucosal Infection with Molecularly Cloned Feline Immunodeficiency Viruses

2003 ◽  
Vol 10 (1) ◽  
pp. 185-188 ◽  
Author(s):  
Mariko Kohmoto ◽  
Yasuhiro Ikeda ◽  
Eiji Sato ◽  
Yorihiro Nishimura ◽  
Yasuo Inoshima ◽  
...  
Keyword(s):  
Virus Strain ◽  
Feline Immunodeficiency Virus ◽  
Deletion Mutant ◽  
Cell Tropism ◽  
Specific Pathogen Free ◽  
Mucosal Epithelium ◽  
Immunodeficiency Virus ◽  
Mucosal Infection ◽  
Specific Pathogen

ABSTRACT Four of six specific pathogen-free cats were infected after intravaginal exposure to molecularly cloned lymphotropic but non-Crandell feline kidney (CRFK)-tropic feline immunodeficiency virus strain TM2 and its AP-1 deletion mutant. The sequences of the env V3-to-V5 region which defines the CRFK tropism were unchanged in the infected cats through the infection. These data suggest that the strain was transmitted across the mucosal epithelium without a broadening of cell tropism.

scholarly journals Lentivirus Infection in the Brain Induces Matrix Metalloproteinase Expression: Role of Envelope Diversity

2000 ◽  
Vol 74 (16) ◽  
pp. 7211-7220 ◽  
Author(s):  
J. B. Johnston ◽  
Y. Jiang ◽  
G. van Marle ◽  
M. B. Mayne ◽  
W. Ni ◽  
...  
Keyword(s):  
Feline Immunodeficiency Virus ◽  
Sequence Diversity ◽  
Conditioned Media ◽  
Envelope Gene ◽  
Cell Tropism ◽  
Protein Levels ◽  
Immunodeficiency Virus ◽  
Envelope Sequence ◽  
The Brain

ABSTRACT Infection of the brain by lentiviruses, including human immunodeficiency virus (HIV) and feline immunodeficiency virus (FIV), causes inflammation and results in neurodegeneration. Molecular diversity within the lentivirus envelope gene has been implicated in the regulation of cell tropism and the host response to infection. Here, we examine the hypothesis that envelope sequence diversity modulates the expression of host molecules implicated in lentivirus-induced brain disease, including matrix metalloproteinases (MMP) and related transcription factors. Infection of primary macrophages by chimeric HIV clones containing brain-derived envelope fragments from patients with HIV-associated dementia (HAD) or nondemented AIDS patients (HIV-ND) showed that MMP-2 and -9 levels in conditioned media were significantly higher for the HAD clones. Similarly, STAT-1 and JAK-1 levels were higher in macrophages infected by HAD clones. Infections of primary feline macrophages by the neurovirulent FIV strain (V1CSF), the less neurovirulent strain (Petaluma), and a chimera containing the V1CSF envelope in a Petaluma background (FIV-Ch) revealed that MMP-2 and -9 levels were significantly higher in conditioned media from V1CSF- and FIV-Ch-infected macrophages, which was associated with increased intracellular STAT-1 and JAK-1 levels. The STAT-1 inhibitor fludarabine significantly reduced MMP-2 expression, but not MMP-9 expression, in FIV-infected macrophages. Analysis of MMP mRNA and protein levels in brain samples from HIV-infected persons or FIV-infected cats showed that MMP-2 and -9 levels were significantly increased in lentivirus-infected brains compared to those of uninfected controls. Elevated MMP expression was accompanied by significant increases in STAT-1 and JAK-1 mRNA and protein levels in the same brain samples. The present findings indicate that two lentiviruses, HIV and FIV, have common mechanisms of MMP-2 and -9 induction, which is modulated in part by envelope sequence diversity and the STAT-1/JAK-1 signaling pathway.

scholarly journals The Second Extracellular Loop of CXCR4 Determines Its Function as a Receptor for Feline Immunodeficiency Virus

1998 ◽  
Vol 72 (8) ◽  
pp. 6475-6481 ◽  
Author(s):  
Brian J. Willett ◽  
Karen Adema ◽  
Nikolaus Heveker ◽  
Anne Brelot ◽  
Laurent Picard ◽  
...  
Keyword(s):  
Feline Immunodeficiency Virus ◽  
Receptor Internalization ◽  
Receptor Function ◽  
Extracellular Loop ◽  
Critical Determinant ◽  
Susceptibility To Infection ◽  
Extracellular Loops ◽  
Immunodeficiency Virus ◽  
Dry Motif ◽  
Infected Cells

ABSTRACT The feline homolog of the α-chemokine receptor CXCR4 has recently been shown to support cell-cell fusion mediated by CXCR4-dependent strains of human immunodeficiency virus (HIV) and strains of feline immunodeficiency virus (FIV) that have been selected for growth in the Crandell feline kidney (CrFK) cell line. In this report we demonstrate that expression of CXCR4 alone is sufficient to render cells from diverse species permissive for fusion with FIV-infected cells, suggesting that CXCR4 is the sole receptor for CrFK-tropic strains of FIV, analogous to CD4-independent strains of HIV-2. To identify the regions of CXCR4 involved in fusion mediated by FIV, we screened panels of chimeric CXCR4 molecules for the ability to support fusion with FIV-infected cells. Human CXCR4 supported fusion more efficiently than feline CXCR4 and feline/human CXCR4 chimeras, suggesting that the second and third extracellular loops of human CXCR4 contain a critical determinant for receptor function. Rat/human CXCR4 chimeras suggested that the second extracellular loop contained the principal determinant for receptor function; however, chimeras constructed between human CXCR2 and CXCR4 revealed that the first and third loops of CXCR4 contribute to the FIV Env binding site, as replacement of these domains with the corresponding domains of CXCR2 rendered the molecule nonfunctional in fusion assays. Mutation of the DRY motif and the C-terminal cytoplasmic tail of CXCR4 did not affect the ability of the molecule to support fusion, suggesting that neither signalling via G proteins nor receptor internalization was required for fusion mediated by FIV; similarly, truncation of the N terminus of CXCR4 did not affect the function of the molecule as a receptor for FIV. CXCR4-transfected feline cells were rendered permissive for infection with both the CrFK-tropic PET isolate of FIV and the CXCR4-dependent RF strain of HIV-1, and susceptibility to infection correlated well with ability to support fusion. The data suggest that the second extracellular loop of CXCR4 is the major determinant of CXCR4 usage by FIV.

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