Human monocytes possess a serine protease activity capable of degrading HIV-1 reverse transcriptase in vitro.
Human immunodeficiency virus type-1 (HIV-1) reverse transcriptase (RT) plays a central role in the virus replication cycle. We found that HIV-1 RT was rapidly degraded when incubated with cell extracts obtained from human peripheral blood cells. The proteolytic activity responsible for the in vitro degradation of RT was present in monocytes and their precursors. Interestingly, this activity was downregulated upon cell activation or differentiation along the macrophage pathway. The proteolytic process appears specific for HIV-1 RT since other HIV-1 proteins were not degraded upon incubation in the same extracts. Although the degradation of RT was unaffected by specific proteasome inhibitors, it could be inhibited by PMSF and aprotinin, suggesting the involvement of a serine protease. Upon cell fractionation, this serine protease was found to be associated with the microsomal fraction and displayed an apparent molecular weight of approximately 2000 kDa, as determined by gel filtration. Our results suggest that a giant serine protease, different from tripeptidyl peptidase II, is involved in the in vitro degradation of HIV-1 RT. The possibility of an in vivo interaction between HIV-1 RT and a cell-type-specific serine protease is discussed.
Château
M T
MT
Centre de Recherches de Biochimie Macromoléculaire, Centre National de la Recherche Scientifique, 1919 route de Mende, Montpellier cedex 05, 34293, France. chateau@crbm.cnrs-mop.fr
Robert-Hebmann
V
V
Devaux
C
C
Lazaro
J B
JB
Canard
B
B
Coux
O
O
D002213:Capsid / Q000378:metabolism; D002454:Cell Differentiation; D015536:Down-Regulation; D015683:Gene Products, gag / Q000378:metabolism; D015488:HIV Antigens / Q000378:metabolism; D054303:HIV Reverse Transcriptase / Q000378:metabolism*; D015497:HIV-1 / Q000378:metabolism; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008861:Microsomes / Q000201:enzymology; D009000:Monocytes / Q000201:enzymology*; D022423:Myeloid Cells / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism*; D020298:U937 Cells; D014764:Viral Proteins; D054301:gag Gene Products, Human Immunodeficiency Virus
D015683:Gene Products, gag; D015488:HIV Antigens; D007211:Indoles; D014764:Viral Proteins; C098807:butabindide; D054301:gag Gene Products, Human Immunodeficiency Virus; C054858:p17 protein, Human Immunodeficiency Virus Type 1; D054303:HIV Reverse Transcriptase; D012697:Serine Endopeptidases