Conservation of L and 3C proteinase activities across distantly related aphthoviruses.
The foot-and-mouth disease virus (FMDV) leader (L) proteinase is an important virulence determinant in FMDV infections. It possesses two distinct catalytic activities: (i) C-terminal processing at the L/VP4 junction; and (ii) induction of the cleavage of translation initiation factor eIF4G, an event that inhibits cap-dependent translation in infected cells. The only other member of the Aphthovirus genus, equine rhinitis A virus (ERAV), also encodes an L protein, but this shares only 32% amino acid identity with its FMDV counterpart. Another more distantly related picornavirus, equine rhinitis B virus (ERBV), which is not classified as an aphthovirus, also encodes an L protein. Using in vitro transcription and translation analysis, we have shown that both ERAV and ERBV L proteins have C-terminal processing activity. Furthermore, expression of ERAV L, but not ERBV L, in BHK-21 cells resulted in the efficient inhibition of cap-dependent translation in these cells. We have shown that the ERAV and FMDV L proteinases induce cleavage of eIF4GI at very similar or identical positions. Interestingly, ERAV 3C also induces eIF4GI cleavage and again produces distinct products that co-migrate with those induced by FMDV 3C. The ERBV L proteinase does not induce eIF4GI cleavage, consistent with its inability to shut down cap-dependent translation. We have also shown that another unique feature of FMDV L, the stimulation of enterovirus internal ribosome entry site (IRES) activity, is also shared by the ERAV L proteinase but not by ERBV L. The functional conservation of the divergent ERAV and FMDV proteinases indicates the likelihood of a similar and important role for these enzymes in the pathogenesis of infections caused by these distantly related aphthoviruses.
Hinton
Tracey M
TM
Department of Microbiology and Immunology and the Co-operative Research Centre for Vaccine Technology, The University of Melbourne, Victoria 3010, Australia1.
Ross-Smith
Natalie
N
BBSRC Institute for Animal Health, Pirbright, Woking, Surrey GU24 0NF, UK2.
Warner
Simone
S
Department of Microbiology and Immunology and the Co-operative Research Centre for Vaccine Technology, The University of Melbourne, Victoria 3010, Australia1.
Belsham
Graham J
GJ
BBSRC Institute for Animal Health, Pirbright, Woking, Surrey GU24 0NF, UK2.
Crabb
Brendan S
BS
The Walter and Eliza Hall Institute of Medical Research, PO The Royal Melbourne Hospital, Melbourne, Victoria 3050, Australia3.
D000086042:3C Viral Proteases; D000595:Amino Acid Sequence; D000818:Animals; D005537:Aphthovirus / Q000201:enzymology* / Q000235:genetics; D002460:Cell Line; D002522:Chlorocebus aethiops; D017124:Conserved Sequence; D006224:Cricetinae; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D010450:Endopeptidases / Q000138:chemical synthesis / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D039603:Eukaryotic Initiation Factor-4G / Q000378:metabolism; D029544:Foot-and-Mouth Disease Virus / Q000201:enzymology / Q000235:genetics; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D014709:Vero Cells; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
D039603:Eukaryotic Initiation Factor-4G; D014764:Viral Proteins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D000086042:3C Viral Proteases; C088747:leader proteinase, foot-and-mouth disease virus