Functions of alphavirus nonstructural proteins in RNA replication

Kääriäinen, Leevi; Ahola, Tero

doi:10.1016/s0079-6603(02)71044-1

Cited by 107 publications

(115 citation statements)

References 164 publications

(244 reference statements)

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“…5). The structural proteins (capsid and three-envelope proteins) are translated as a polyprotein from a separate subgenomic 26 S mRNA, which is a copy of the 3Ј-end of the genome arising during the RNA replication process.…”

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confidence: 99%

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Regulation of the Sequential Processing of Semliki Forest Virus Replicase Polyprotein

Vasiljeva

Merits

Golubtsov

et al. 2003

Journal of Biological Chemistry

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113

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The replication of most positive-strand RNA viruses and retroviruses is regulated by proteolytic processing. Alphavirus replicase proteins are synthesized as a polyprotein, called P1234, which is cleaved into nsP1, nsP2, nsP3, and nsP4 by the carboxyl-terminal protease domain of nsP2. The cleavage intermediate P123؉nsP4 synthesizes minus-strand copies of the viral RNA genome, whereas the completely processed complex is required for plus-strand synthesis. To understand the mechanisms responsible for this sequential proteolysis, we analyzed in vitro translated Semliki Forest virus polyproteins containing noncleavable processing sites or various deletions. Processing of each of the three sites in vitro required a different type of activity. Site 3/4 was cleaved in trans by nsP2, its carboxyl-terminal fragment Pro39, and by all polyprotein proteases. Site 1/2 was cleaved in cis with a half-life of about 20 -30 min. Site 2/3 was cleaved rapidly in trans but only after release of nsP1 from the polyprotein exposing an "activator" sequence present in the amino terminus of nsP2. Deletion of amino-terminal amino acids of nsP2 or addition of extra amino acid residues to its amino terminus specifically inhibited the protease activity that processes the 2/3 site. This sequence of delayed processing of P1234 would explain the accumulation of P123 plus nsP4, the early short-lived minus-strand replicase. The polyprotein stage would allow correct assembly and membrane association of the RNA-polymerase complex. Late in infection free nsP2 would cleave at site 2/3 yielding P12 and P34, the products of which, nsP1-4, are distributed to the plasma membrane, nucleus, cytoplasmic aggregates, and proteasomes, respectively.

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confidence: 99%

“…The nsPs possess enzymatic and other functions needed for virus RNA replication. NsP4 is the catalytic RNA-dependent RNA polymerase subunit, and nsP3 is an evolutionarily conserved protein of unknown function (5). The amino-terminal domain of nsP2 has NTPase, RNA helicase, and RNA triphosphatase activities (10 -12).…”

mentioning

confidence: 99%

Regulation of the Sequential Processing of Semliki Forest Virus Replicase Polyprotein

Vasiljeva

Merits

Golubtsov

et al. 2003

Journal of Biological Chemistry

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113

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“…42 These cellular structures are formed from endosomes and lysosomes 3 h after an SFV infection, and appear crucial for plus strand RNA synthesis. 43 The nsP 1 has an essential role in determining membrane association (Figure 3). [42][43][44] This protein contains two membrane-targeting signals, a stretch of 19 charged and hydrophobic amino acids interacting with phospholipids, and three palmitoylated cysteins.…”

Section: Cellular Factors and Sfv Vectorsmentioning

confidence: 99%

“…43 The nsP 1 has an essential role in determining membrane association (Figure 3). [42][43][44] This protein contains two membrane-targeting signals, a stretch of 19 charged and hydrophobic amino acids interacting with phospholipids, and three palmitoylated cysteins. It is noteworthy that the membrane association of nsP 1 regulates the enzymatic activity of the protein.…”

Section: Cellular Factors and Sfv Vectorsmentioning

confidence: 99%

“…It is noteworthy that the membrane association of nsP 1 regulates the enzymatic activity of the protein. 43 Whereas nsP 1 missing the palmitoylation signal is still weakly associated with the plasma membrane, replicons harbouring this mutation are severely impaired in their replication (E Piver unpublished data and A Merits personal communication). Therefore, membrane targeting might be essential to SFV replication.…”

Section: Cellular Factors and Sfv Vectorsmentioning

confidence: 99%

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Cellular factors influencing Semliki Forest Virus vector biology

et al. 2005

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Network mapping among the functional domains of Chikungunya virus nonstructural proteins

Rana

Rajasekharan

Gulati³

et al. 2014

Proteins

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Formation of virus specific replicase complex is among the most important steps that determines the fate of viral transcription and replication during Chikungunya virus (CHIKV) infection. In the present study, the authors have computationally generated a 3D structure of CHIKV late replicase complex on the basis of the interactions identified among the domains of CHIKV nonstructural proteins (nsPs) which make up the late replicase complex. The interactions among the domains of CHIKV nsPs were identified using systems such as pull down, protein interaction ELISA, and yeast two-hybrid. The structures of nsPs were generated using I-TASSER and the biological assembly of the replicase complex was determined using ZRANK and RDOCK. A total of 36 interactions among the domains and full length proteins were tested and 12 novel interactions have been identified. These interactions included the homodimerization of nsP1 and nsP4 through their respective C-ter domains; the associations of nsP2 helicase domain and C-ter domain of nsP4 with methyltransferase and membrane binding domains of nsP1; the interaction of nsP2 protease domain with C-ter domain of nsP4; and the interaction of nsP3 macro and alphavirus unique domains with the C-ter domain of nsP1. The novel interactions identified in the current study form a network of organized associations that suggest the spatial arrangement of nsPs in the late replicase complex of CHIKV.

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Functions of alphavirus nonstructural proteins in RNA replication

Cited by 107 publications

References 164 publications

Regulation of the Sequential Processing of Semliki Forest Virus Replicase Polyprotein

Regulation of the Sequential Processing of Semliki Forest Virus Replicase Polyprotein

Cellular factors influencing Semliki Forest Virus vector biology

Network mapping among the functional domains of Chikungunya virus nonstructural proteins

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