Mycoplasmas are known to enhance human immunodeficiency virus (HIV) replication, and mycoplasma-derived lipid extracts have been reported to activate nuclear factor-kappaB (NF-kappaB) through Toll-like receptors (TLRs). In this study, we examined the involvement of TLRs in the activation of HIV long-terminal repeats (LTR) by mycoplasma and their active components responsible for the TLR activation. Lipid-associated membrane proteins (LAMPs) from two species of mycoplasma (Mycoplasma fermentans and M. penetrans) that are associated with acquired immune-deficiency syndrome (AIDS), were found to activate HIV LTRs in a human monocytic cell line, THP-1. NF-kappaB deletion from the LTR resulted in inhibition of the activation. The LTR activation by M. fermentans LAMPs was inhibited by a dominant negative (DN) construct of TLR1 and TLR6, whereas HIV LTR activation by M. penetrans LAMPs was inhibited by DN TLR1, but not by DN TLR6. These results indicate that the activation of HIV LTRs by M. fermentans and M. penetrans LAMPs is dependent on NF-kappaB, and that the activation of HIV LTR by M. fermentans LAMPs is mediated through TLR1, TLR2 and TLR6. In contrast, the LTR activation by M. penetrans LAMPs is carried out through TLR1 and TLR2, but not TLR6. Subsequently, the active component of M. penetrans and M. fermentans LAMPs was purified by reverse-phase high-performance liquid chromatography (HPLC). Interestingly, the purified lipoprotein of M. penetrans LAMPs (LPMp) was able to activate NF-kappaB through TLR1 and TLR2. On the other hand, the activation of NF-kappaB by purified lipoprotein of M. fermentans LAMPs (LPMf) was mediated through TLR2 and TLR6, but not TLR1.