Rotaviruses code for two types of glycoprotein precursors

Area of Science:

• Virology
• Molecular Biology
• Cell Biology

Background:

• Rotaviruses are nonenveloped viruses encoding two key glycoproteins: VP7 and NS29.
• Understanding glycoprotein synthesis is crucial for viral replication and morphogenesis.

Purpose of the Study:

• To investigate the synthesis and processing of rotavirus glycoproteins, VP7 and NS29.
• To elucidate the role of signal sequences in membrane insertion and glycosylation.

Main Methods:

• Cell-free synthesis of rotavirus glycoprotein precursors (37K for VP7, 20K for NS29).
• Utilized dog pancreatic microsomes for studying signal sequence cleavage and glycosylation.
• Analyzed cotranslational membrane insertion and posttranslational oligosaccharide processing.

Main Results:

• The VP7 precursor (37K) possesses a cleavable signal sequence, enabling authentic processing via signal sequence cleavage and core glycosylation.
• The NS29 precursor (20K) contains a non-cleavable, integral signal sequence.
• Both precursors were cotranslationally inserted into membranes, and their glycosylated products underwent posttranslational oligosaccharide modification.

Conclusions:

• The findings provide a detailed morphogenetic scheme for simian rotavirus SA11.
• Differential signal sequence processing dictates distinct pathways for rotavirus glycoprotein maturation.