Affiliation:
1. Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030
2. Department of Microbiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
Abstract
ABSTRACT
Poliovirus (PV) causes a rapid and drastic inhibition of host cell cap-dependent protein synthesis during infection while preferentially allowing cap-independent translation of its own genomic RNA via an internal ribosome entry site element. Inhibition of cap-dependent translation is partly mediated by cleavage of an essential translation initiation factor, eIF4GI, during PV infection. In addition to cleavage of eIF4GI, cleavage of eIF4GII and poly(A)-binding protein (PABP) has been recently proposed to contribute to complete host translation shutoff; however, the relative importance of eIF4GII and PABP cleavage has not been determined. At times when cap-dependent translation is first blocked during infection, only 25 to 35% of the total cellular PABP is cleaved; therefore, we hypothesized that the pool of PABP associated with polysomes may be preferentially targeted by viral proteases. We have investigated what cleavage products of PABP are produced in vivo and the substrate determinants for cleavage of PABP by 2A protease (2A
pro
) or 3C protease (3C
pro
). Our results show that PABP in ribosome-enriched fractions is preferentially cleaved in vitro and in vivo compared to PABP in other fractions. Furthermore, we have identified four N-terminal PABP cleavage products produced during PV infection and have shown that viral 3C protease generates three of the four cleavage products. Also, 3C
pro
is more efficient in cleaving PABP in ribosome-enriched fractions than 2A
pro
in vitro. In addition, binding of PABP to poly(A) RNA stimulates 3C
pro
-mediated cleavage and inhibits 2A
pro
-mediated cleavage. These results suggest that 3C
pro
plays a major role in processing PABP during virus infection and that the interaction of PABP with translation initiation factors, ribosomes, or poly(A) RNA may promote its cleavage by viral 2A and 3C proteases.
Publisher
American Society for Microbiology
Subject
Virology,Insect Science,Immunology,Microbiology
Reference76 articles.
1. Asselbergs, F., W. Peters, W. van Venrooij, and H. Bloemendal. 1978. Diminished sensitivity of re-initiation of translation to inhibition by cap analogues in reticulocyte lysates. Eur. J. Biochem. 88 : 483-488.
2. Baer, B. W., and R. D. Kornberg. 1983. The protein responsible for the repeating structure of cytoplasmic poly(A)-ribonucleoprotein. J. Cell Biol. 96 : 717-721.
3. Bag, J., and J. Wu. 1996. Translational control of poly(A)-binding protein expression. Eur. J. Biochem. 237 : 143-152.
4. Baker, E. J. 1993. Control of poly(A) length, p. 367-415. In J. G. Belasco and G. Brawerman (ed.), Control of messenger RNA stability. Academic Press, San Diego, Calif.
5. A Stable HeLa Cell Line That Inducibly Expresses Poliovirus 2A
pro
: Effects on Cellular and Viral Gene Expression
Cited by
116 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献