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Table 1 The functions of non-structural proteins of SARS-CoV-2

From: SARS coronavirus 2: from genome to infectome

S. no

Proteins

Functions

Refs

1.

nsp1

Interferes with the mRNA binding and suppresses hosts’ immune functions

Anchors the replication complex to cellular membranes

Degrades host’s mRNA by interacting with the human 40S ribosomal subunit

[132, 133]

2.

nsp2

Harbours mutations that make it more contagious

Might play a role in modulation of host cell survival; also known as p65 homolog

[132, 134]

3.

nsp3

Papain-like protease 2 (PL2pro) involved in proteolytic cleavage

[135]

4.

nsp4

Responsible for the formation of the double membrane vesicle during replication

Anchors the viral replication-transcription complex to the membranes of endoplasmic reticulum

[136, 137]

5.

nsp5

Proteases (3CLpro, Mpro) involved in polypeptide cleaving

[138]

6.

nsp6

Prevents the expansion of autophagosome, Help in formation of double membrane vesicle; suppresses IFN-I signaling

[139, 140]

7.

nsp7

Forms a hexadecamer with nsp8 and acts as a primase in viral replication

[141]

8.

nsp8

Acts as a primase with nsp7

[142, 143]

9.

nsp9

Acts as ssRNA binding protein

[143, 144]

10.

nsp10

Plays role in the methylation of viral mRNA cap. Stimulates the nsp14 3′-5′ exoribonuclease and 2′-O-methyltransferase (NSP16) activities

[144]

11

nsp11

Unknown

 

12

nsp12

Catalytic subunit of the RNA-dependent RNA polymerase; Catalyses the synthesis of viral RNA, using nsp7 and nsp8 as cofactors

[142, 145, 146]

13.

nsp13

Helicase and NTPase activity: hydrolyze the NTPs and unwind the duplex RNA and DNA with a 5′ single-stranded tail in a 5′ to 3′ direction

A potent interferon antagonist

[147,148,149]

14.

nsp14

Guanine-N7 methyltransferase, a multienzyme complex

Acts on both sides ssRNA and dsRNA in a 3′-> 5′ direction

A potent interferon antagonist

It plays role in genome replication, sub-genomic RNA synthesis and recombination

[132, 148, 150]

15.

nsp15

It is a nidoviral RNA uridylate‐specific endoribonuclease (NendoU); plays role in viral replication and transcription

A potent interferon antagonist

[148, 151, 152]

16.

nsp16

Acts as 2′-O-methyltransferase that mediates mRNA cap 2′-O-ribose methylation to the 5′-cap structure of viral mRNAs

[148, 153]