Proteolytic processing of foamy virus Gag and Pol proteins.
The foamy viral proteases (FV PRs) are set apart from other retroviral processing enzymes by unique features. The first remarkable property is that FV PRs are enzymatically active as high-molecular-mass Pro-Pol proteins. Hence there exist multiple forms of active FV PRs that likely contribute to cleavage site specificity. A FV PR of low molecular size is not detectable in purified virions, in contrast to PRs of other retroviruses that are found in virus particles. Because the major part of Pol remains attached to the amino-terminal enzymatically active PR protein region, the FV-specific way of expressing Pro-Pol polyproteins from a pol-specific transcript provides for the incorporation of Pro-Pol and IN into virus particles. Proteolytic processing of Gag and Pol proteins is incomplete and delayed. Another novel feature is that the catalytic center of the active dimers of cat FV PR consists of D-S/T-Q instead of D-S/T-G, an unprecedented feature of this enzyme. The temporal and spatial control and the factors that regulate FV PRs remain to be elucidated.
Flügel
R M
RM
Retroviral Gene Expression, Research Programme Applied Tumor Virology, German Cancer Research Center, Im Neuenheimer Feld 242, 69009 Heidelberg, Germany. r.m.fluegel@dkfz-heidelberg.de
Pfrepper
K I
KI
D000595:Amino Acid Sequence; D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D015685:Fusion Proteins, gag-pol / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D015967:Gene Expression Regulation, Viral; D015686:Gene Products, env / Q000235:genetics / Q000502:physiology; D015683:Gene Products, gag / Q000096:biosynthesis / Q000378:metabolism*; D015684:Gene Products, pol / Q000096:biosynthesis / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D020815:Polyproteins / Q000737:chemistry / Q000502:physiology; D011499:Protein Processing, Post-Translational; D011817:Rabbits; D016092:Spumavirus / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D014771:Virion / Q000502:physiology; D019065:Virus Assembly
D015685:Fusion Proteins, gag-pol; D015686:Gene Products, env; D015683:Gene Products, gag; D015684:Gene Products, pol; D020815:Polyproteins; D016282:Aspartic Acid Endopeptidases; C096363:proteinase, foamy virus