Faculty Bibliography

GAP31 (gelonium anti-HIV protein of 31 kDa) is an anti-HIV protein which we have identified and purified from a medicinal plant, Gelonium multiflorum. It is capable of inhibiting HIV-1 infection and replication. GAP31 also exhibits DNA topoisomerase inhibitor activity and RNA N-glycosidase activity. The ability of GAP31 to interrupt both DNA and RNA functions may be related to its multiple antiviral actions. To define the roles of these activities in the anti-HIV action of GAP31, a series of peptides corresponding to the N-terminal segment of GAP31 were synthesized and assayed for the aforementioned activities of the parent molecule. A 33-aa segment (KGATYITYVNFLNELRVKTKPEGNSHGIPSLRK) designated as K10-K42 is the shortest peptide necessary and sufficient for HIV-1 inhibition, DNA and RNA binding, and ribosome inactivation. The peptides were 2-5 orders of magnitude less active than GAP31. Truncation of 19 aa from the C terminus of K10-K42 resulted in the loss of all of these activities. On the other hand, deletion of N-terminal residues to give E23-K42 did not alter ribosome-inactivation activity but eliminated the other activities. These findings permit identification of a 7-aa sequence, KGATYIT, at the N terminus of K10-K42 that is critical for DNA binding and RNA binding, whereas a 9-aa sequence, SHGIPSLRK, at the C terminus is important to ribosome inactivation. Both regions contribute to anti-HIV activity. Histidine at position 35 is critical for all of these activities. The disparity of sequence requirements for inhibition of HIV infection and replication and for ribosome-inactivation activity suggests that the anti-HIV activity of most ribosome-inactivating proteins may not be the result of N-glycosidase activity alone. Mapping the minimal domain of GAP31 offers insights into the rational design of molecular mimetics of anti-HIV drugs

MAP 30 and GAP 31 are plant proteins isolated from Momordica charantia and Gelonium multiflorum, respectively. They have recently been shown to inhibit HIV-1 infection and replication. These proteins also possess a novel DNA topoisomerase-poison-like activity as well as ribosome inactivation. They were submitted to the Anti-Cancer Drug Screening Program of the National Cancer Institute and found to have potent anti-tumor activity against certain human tumor cell lines. The most sensitive cell lines responded to MAP 30 and GAP 31 with GI(50) that ranged from 0.01 to 10 mu g/ml and were unrelated to tumor type. These included cell lines from renal, non-small cell lung, and breast cancer. Targeted immunofusions made with MAP 30 or GAP 31 may be most effective toward these types of tumors.

GAP 31 is an anti-HIV plant protein that we have identified and purified to homogeneity from Gelonium multiflorum. It is the first reported example of an anti-HIV agent capable of acting against multiple stages of the viral life cycle, on viral infection and viral replication. GAP 31 is a unique paragon of multi-functional protein. In addition to anti-HIV activity, it also exhibits anti-tumor action, DNA binding, RNA binding and ribosome inactivation. The present crystals diffract up to 2.0 A resolution and belong to monoclinic space group P2(1). The cell dimensions are a = 49.30(2) A, b = 44.57(2) A, c = 137.78(7) A and beta = 98.32(3) degrees. There are two molecules of molecular weight 31 kDa in an asymmetric unit with a solvent content of 49%

Gramicidin, a polypeptide antibiotic derived from Bacillus brevis, was compared in vitro with the established contraceptive virucidal agents nonoxynol-9 and gossypol for activity against human immunodeficiency virus (HIV) infection. The effective antiviral 10 ng/ml concentration of gramicidin required for complete HIV inactivation was a thousand-fold lower than the dose observed for nonoxynol-9 or gossypol. Gramicidin, routinely used as a contraceptive agent in the former Soviet Union, should be considered for in vivo trials as a spermicide with potent antiviral activity

An anthelminthic agent, levamisole, also known as a potent immunomodulator, has been successfully used for adjuvant therapy of malignancies and chronic infections underlined by immunodeficiency. We have tested the effect of this drug on de novo viral infection by exposing MT-4 T lymphocytes to HIV in the presence of serial ten-fold dilutions of levamisole (range 10(-3)-10(-9) M). The results indicate that 50% reduction in viral infectivity (IC50) of levamisole starts from as low as 10(-7) M, whereas even the highest millimolar dose of the drug has not shown any appreciable cytotoxicity. Although the mechanism of levamisole action remains unknown, our observation in vitro suggests that levamisole, a clinically established immunomodulator, can be potentially effective for treatment of HIV infection

The antiviral effect of the immunomodulating anti-cancer agent, bestatin, was examined in vitro by exposing MT-4 lymphocytes to HIV in the presence of 10-fold dilutions of drug (range 100 micrograms-100 pg/ml). The reduction in infectivity was measured by p24 ELISA and compared to the effect of established anti-HIV drugs-azidothymidine (AZT) and dextran sulfate. The results indicate that low doses of bestatin (1 microgram/ml) can completely inhibit viral infection resulting either from inoculation with free virus or coculture with infected lymphocytes. Unlike AZT or dextran sulfate, bestatin prevents HIV infection without interfering with the rate of cell growth. No appreciable decrease in HIV production was observed when chronically infected virus-producing T cell lines ie, H9, MOLT-4, HPB-ALL, 8E5 and MT-2 were treated with bestatin. Bestatin appears to act in the early stages of viral penetration, possibly through inhibition of lymphocyte-associated aminopeptidases

We have reported the identification of a classical canonical CAAT box, TATA boxes and other transcriptional regulatory elements in the 5' flanking region of the human erythropoietin (hEp)-encoding gene [Lee-Huang et al., Gene 128 (1993) 227-236]. These elements were not found in the hEp genomic clones reported by others. Our genomic clone extends in both directions beyond any reported clones, by 3.9 kb on the 5' side and by 1.8 kb on the 3' side. Many important regulatory elements are found in these extended flanking regions. We report here the genomic structure of the extended 3' flanking region of hEp. This region contains the following regulatory elements: nitrogen-regulatory/oxygen-sensing consensus sequences, 5'-TTTTGCA and 5'-CCCTGCA; tissue-specific regulatory elements, including binding sites for A-activator, 5'-GTGGTGCAA; for DBP, 5'-TGATTTTGT; for HNF, 5'-T(A/G)TTTGT; and for C/EBP, 5'-T(T/G) (T/G)TGCAAT; a lymphokine-responsive element, 5'-GTGAAACCCC (Rev), as well as binding sites for AP and Sp1. In addition, the nucleotide (nt) sequence in this region is rich in inverted repeats (palindromes) that allow the formation of hairpin loops. A total of 14 potential stem loops with a maximum loop size of 20 nt are found. The identification of these regulatory elements in hEp should provide further insight into the tissue-specific and inducible expression of hEp. Such knowledge should be useful in the clinical modulation of erythropoiesis under physiologic and pathologic conditions