Heterogeneous nuclear ribonucleoprotein A1 binds to the transcription-regulatory region of mouse hepatitis virus RNA

Heterogeneous nuclear ribonucleoprotein A1 binds to the transcription-regulatory region of mouse hepatitis virus RNA

^*Department of Molecular Microbiology and Immunology and ^§Howard Hughes Medical Institute, University of Southern California Schools of Medicine, Los Angeles, CA 90033; and ^‡University of Southern California School of Pharmacy, Los Angeles, CA 90033

Communicated by Paul Ahlquist, University of Wisconsin, Madison, WI (received for review April 21, 1997)

Abstract

A cellular protein, previously described as p35/38, binds to the complementary (−)-strand of the leader RNA and intergenic (IG) sequence of mouse hepatitis virus (MHV) RNA. The extent of the binding of this protein to IG sites correlates with the efficiency of the subgenomic mRNA transcription from that IG site, suggesting that it is a requisite transcription factor. We have purified this protein and determined by partial peptide sequencing that it is heterogeneous nuclear ribonucleoprotein (hnRNP) A1, an abundant, primarily nuclear protein. hnRNP A1 shuttles between the nucleus and cytoplasm and plays a role in the regulation of alternative RNA splicing. The MHV(−)-strand leader and IG sequences conform to the consensus binding motifs of hnRNP A1. Recombinant hnRNP A1 bound to these two RNA regions in vitro in a sequence-specific manner. During MHV infection, hnRNP A1 relocalizes from the nucleus to the cytoplasm, where viral replication occurs. These data suggest that hnRNP A1 is a cellular factor that regulates the RNA-dependent RNA transcription of the virus.

Footnotes

↵ † Present address: Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205.
↵ ¶ To whom reprint requests should be addressed. e-mail: michlai{at}hsc.usc.edu.
ABBREVIATIONS:

MHV,

mouse hepatitis virus;

IG,

intergenic;

hnRNP,

heterogeneous nuclear ribonucleoprotein;

2-D,

two-dimensional;

GST,

glutathione S-transferase;

RBD,

RNA-binding domain