Characterization of Functional Domains of Equine Infectious Anemia Virus Rev Suggests a Bipartite RNA-Binding Domain

ABSTRACT Equine infectious anemia virus (EIAV) Rev is an essential regulatory protein that facilitates expression of viral mRNAs encoding structural proteins and genomic RNA and regulates alternative splicing of the bicistronic tat/rev mRNA. EIAV Rev is characterized by a high rate of genetic variation in vivo, and changes in Rev genotype and phenotype have been shown to coincide with changes in clinical disease. To better understand how genetic variation alters Rev phenotype, we undertook deletion and mutational analyses to map functional domains and to identify specific motifs that are essential for EIAV Rev activity. All functional domains are contained within the second exon of EIAV Rev. The overall organization of domains within Rev exon 2 includes a nuclear export signal, a large central region required for RNA binding, a nonessential region, and a C-terminal region required for both nuclear localization and RNA binding. Subcellular localization of green fluorescent protein-Rev mutants indicated that basic residues within the KRRRK motif in the C-terminal region of Rev are necessary for targeting of Rev to the nucleus. Two separate regions of Rev were necessary for RNA binding: a central region encompassing residues 57 to 130 and a C-terminal region spanning residues 144 to 165. Within these regions were two distinct, short arginine-rich motifs essential for RNA binding, including an RRDRW motif in the central region and the KRRRK motif near the C terminus. These findings suggest that EIAV Rev utilizes a bipartite RNA-binding domain.

Download Full-text

Mapping of Equine Lentivirus Receptor 1 Residues Critical for Equine Infectious Anemia Virus Envelope Binding

Journal of Virology ◽

10.1128/jvi.01393-07 ◽

2007 ◽

Vol 82 (3) ◽

pp. 1204-1213 ◽

Cited By ~ 15

Author(s):

Baoshan Zhang ◽

Chengqun Sun ◽

Sha Jin ◽

Michael Cascio ◽

Ronald C. Montelaro

Keyword(s):

Equine Infectious Anemia Virus ◽

Tumor Necrosis Factor Receptor ◽

Binding Domain ◽

Virus Envelope ◽

Immunodeficiency Virus ◽

Equine Infectious Anemia ◽

Anemia Virus ◽

Functional Receptor ◽

Herpesvirus Entry Mediator ◽

Necrosis Factor

ABSTRACT The equine lentivirus receptor 1 (ELR1), a member of the tumor necrosis factor receptor (TNFR) protein family, has been identified as a functional receptor for equine infectious anemia virus (EIAV). Toward defining the functional interactions between the EIAV SU protein (gp90) and its ELR1 receptor, we mapped the gp90 binding domain of ELR1 by a combination of binding and functional assays using the EIAV SU gp90 protein and various chimeric receptor proteins derived from exchanges between the functional ELR1 and the nonbinding homolog, mouse herpesvirus entry mediator (murine HveA). Complementary exchanges of the respective cysteine-rich domains (CRD) between the ELR1 and murine HveA proteins revealed CRD1 as the predominant determinant of functional gp90 binding to ELR1 and also to a chimeric murine HveA protein expressed on the surface of transfected Cf2Th cells. Mutations of individual amino acids in the CRD1 segment of ELR1 and murine HveA indicated the Leu70 in CRD1 as essential for functional binding of EIAV gp90 and for virus infection of transduced Cf2Th cells. The specificity of the EIAV SU binding domain identified for the ELR1 receptor is fundamentally identical to that reported previously for functional binding of feline immunodeficiency virus SU to its coreceptor CD134, another TNFR protein. These results indicate unexpected common features of the specific mechanisms by which diverse lentiviruses can employ TNFR proteins as functional receptors.

Download Full-text

Naturally arising point mutations in non-essential domains of equine infectious anemia virus Rev alter Rev-dependent nuclear-export activity

Journal of General Virology ◽

10.1099/vir.0.83195-0 ◽

2008 ◽

Vol 89 (4) ◽

pp. 1043-1048 ◽

Cited By ~ 8

Author(s):

Wendy O. Sparks ◽

Karin S. Dorman ◽

Sijun Liu ◽

Susan Carpenter

Keyword(s):

Genetic Variation ◽

Nuclear Export ◽

Equine Infectious Anemia Virus ◽

Clinical Stage ◽

Point Mutations ◽

High Rate ◽

Sample Population ◽

Equine Infectious Anemia ◽

Anemia Virus

Equine infectious anemia virus (EIAV) exhibits a high rate of genetic variation in vivo, and results in a clinically variable disease in infected horses. In vivo populations of EIAV have been characterized by the presence of distinct, genetic subpopulations of Rev that differ in phenotype and fluctuate in dominance in a manner coincident with each clinical stage of disease. This study examined the specific mutations that arose in vivo and altered the phenotype. The Rev protein was found to be highly conserved, and only 10 aa mutations were observed at a frequency greater than 10 % in the sample population. Nine of these mutations were capable of significantly altering Rev activity, either as single mutations in the context of the founder variant, or in the context of cumulatively fixed mutations. The results indicated that limited genetic variation outside the essential functional domains of Rev can alter the phenotype and may confer a selective advantage in vivo.

Download Full-text

The comparison of genetic variation in the envelope protein between various immunodeficiency viruses and equine infectious anemia virus

Virologica Sinica ◽

10.1007/s12250-012-3253-x ◽

2012 ◽

Vol 27 (4) ◽

pp. 241-247 ◽

Cited By ~ 1

Author(s):

Qing Yuan ◽

Chang Liu ◽

Zhipin Liang ◽

Xueqing Chen ◽

Danhong Diao ◽

...

Keyword(s):

Genetic Variation ◽

Envelope Protein ◽

Equine Infectious Anemia Virus ◽

Equine Infectious Anemia ◽

Anemia Virus

Download Full-text

Identification and phylogenetic analysis of RNA binding domain abundant in apicomplexans or RAP proteins

Microbial Genomics ◽

10.1099/mgen.0.000541 ◽

2021 ◽

Author(s):

Thomas Hollin ◽

Lukasz Jaroszewski ◽

Jason E. Stajich ◽

Adam Godzik ◽

Karine G. Le Roch

Keyword(s):

Potential Function ◽

Phylogenetic Trees ◽

Rna Binding ◽

Binding Domain ◽

Terminal Region ◽

Protein Domain ◽

Phylogenetic Groups ◽

Apicomplexan Parasites ◽

History Of ◽

Rna Binding Domain

The RNA binding domain abundant in apicomplexans (RAP) is a protein domain identified in a diverse group of proteins, called RAP proteins, many of which have been shown to be involved in RNA binding. To understand the expansion and potential function of the RAP proteins, we conducted a hidden Markov model based screen among the proteomes of 54 eukaryotes, 17 bacteria and 12 archaea. We demonstrated that the domain is present in closely and distantly related organisms with particular expansions in Alveolata and Chlorophyta, and are not unique to Apicomplexa as previously believed. All RAP proteins identified can be decomposed into two parts. In the N-terminal region, the presence of variable helical repeats seems to participate in the specific targeting of diverse RNAs, while the RAP domain is mostly identified in the C-terminal region and is highly conserved across the different phylogenetic groups studied. Several conserved residues defining the signature motif could be crucial to ensure the function(s) of the RAP proteins. Modelling of RAP domains in apicomplexan parasites confirmed an ⍺/β structure of a restriction endonuclease-like fold. The phylogenetic trees generated from multiple alignment of RAP domains and full-length proteins from various distantly related eukaryotes indicated a complex evolutionary history of this family. We further discuss these results to assess the potential function of this protein family in apicomplexan parasites.

Download Full-text