Actinohivin, a Novel Anti-HIV Protein from an Actinomycete That Inhibits Syncytium Formation: Isolation, Characterization, and Biological Activities

Chiba, Harumi; Inokoshi, Junji; Okamoto, Makihito; Asanuma, Satoshi; Matsuzaki, Keiichi; Iwama, Minako; Mizumoto, Kiyohisa; Tanaka, Haruo; Oh-eda, Masayoshi; Fujita, Kazunobu; Nakashima, Hideki; Shinose, Mayumi; Takahashi, Yōko; Ōmura, Satoshi

doi:10.1006/bbrc.2001.4495

Cited by 55 publications

(51 citation statements)

References 22 publications

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“…5 indicate that AH can also bind to HMTGs other than the epitope of 2G12. Incidentally, the inhibitory activity of AH against gp120-soluble CD4 binding is very weak (IC 50 ϭ 1.2 mM by ELISA) (6). It seems to show that HMTGs are not involved in gp120 binding to CD4 on susceptible cells, and that AH interferes with the entry steps after gp120-CD4 binding occurs.…”

Section: Discussionmentioning

confidence: 95%

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Mechanism by which the lectin actinohivin blocks HIV infection of target cells

Tanaka

Chiba²,

Inokoshi³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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Various lectins have attracted attention as potential microbicides to prevent HIV transmission. Their capacity to bind glycoproteins has been suggested as a means to block HIV binding and entry into susceptible cells. The previously undescribed lectin actinohivin (AH), isolated by us from an actinomycete, exhibits potent in vitro anti-HIV activity by binding to high-mannose (Man) type glycans (HMTGs) of gp120, an envelope glycoprotein of HIV. AH contains 114 aa and consists of three segments, all of which need to show high affinity to gp120 for the anti-HIV characteristic. To generate the needed mechanistic understanding of AH binding to HIV in anticipation of seeking approval for human testing as a microbicide, we have used multiple molecular tools to characterize it. AH showed a weak affinity to Man␣(1-2)Man, Man␣(1-2)Man␣(1-2)Man, of HMTG (Man8 or Man9) or RNase B (which has a single HMTG), but exhibited a strong and highly specific affinity (K d ‫؍‬ 3.4 ؋ 10 ؊8 M) to gp120 of HIV, which contains multiple Man8 and/or Man9 units. We have compared AH to an alternative lectin, cyanovirin-N, which did not display similar levels of discrimination between high-and low-density HMTGs. X-ray crystal analysis of AH revealed a 3D structure containing three sugar-binding pockets. Thus, the strong specific affinity of AH to gp120 is considered to be due to multivalent interaction of the three sugar-binding pockets with three HMTGs of gp120 via the ''cluster effect'' of lectin. Thus, AH is a good candidate for investigation as a safe microbicide to help prevent HIV transmission.action mechanism ͉ anti-HIV ͉ gp120 ͉ high-mannose type glycan ͉ cyanovirin-N

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Section: Discussionmentioning

confidence: 95%

“…T (6)(7)(8). AH exhibits potent anti-HIV activity against various strains of T-tropic and M-tropic HIV-1 and HIV-2 (IC 50 ϭ 2-110 nM) and inhibits viral entry to cells by binding to the high-Man type glycans (HMTGs) of gp120 (9).…”

mentioning

confidence: 99%

Mechanism by which the lectin actinohivin blocks HIV infection of target cells

Tanaka

Chiba²,

Inokoshi³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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“…This flexible and novel approach has, for example, allowed us to obtain the mangromicins, which have a unique cyclopentadecane structure from Lechevalieria aerocolonigenes K10-0216, which originated in mangrove soil, the lariatins that have a lasso structure from Rhodococcus jostii K01-B0171, and actinohivin that displays anti-HIV activity from Longispora albida K97-0003 T which was isolated using a gellan gum medium instead of agar. [42][43][44] These producing strains are rare actinomycetes which occasionally produce different metabolites from Streptomyces strains. Most of actinomycetes producing enediyne antibiotics are also rare actinomycetes, such as Micromonospora strain which produce dynamicin and Actinomadura strain which produce maduropeptin.…”

Section: Search For Novel Compound From Endophytic Actinomycetesmentioning

confidence: 99%

Endophytic actinomycetes: promising source of novel bioactive compounds

2017

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Endophytic actinomycetes associated with plant roots are a relatively untapped source of potential new bioactive compounds. This is becoming increasingly important, as the returns from discovery research on soil-dwelling microbes, have been continuously diminishing. We have isolated more than 1000 strains of actinomycetes from plant roots in our search for novel bioactive compounds, identified and assayed their bioactive metabolites, as well as investigated their biosynthetic genes for generating secondary metabolites. This has resulted in the discovery of several interesting compounds. Creation of plant root clone libraries enabled us to confirm that we had, indeed, isolated endophytes. In this paper, we introduce our approach to this promising line of research, incorporating data from other publications, and illustrate the potential that endophytic actinomycetes offer as a new source of novel lead compounds.

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“…nov. 8 It inhibits the entry of various HIV-1 and HIV-2 strains into susceptible cells (IC 50 ¼2-110 nM), as well as T-tropic and M-tropic syncytium formation (IC 50 ¼60 and 700 nM). 9,10 This inhibitory effect of AH is brought about by potent binding to HIV gp120 through specific interaction with Man-a(1-2)-Man units of HMTGs on gp120. 11,12 AH is composed of 114 amino acid residues and contains three tandem repeats (amino acids 1-38, 39-76 and 77-114; segments 1, 2 and 3, respectively), with each segment containing well-conserved LD-QXW motifs.…”

Section: Introductionmentioning

confidence: 99%

Actinohivin: specific amino acid residues essential for anti-HIV activity

et al. 2010

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Actinohivin (AH) is a microbial lectin containing 114 amino acids, which inhibits human immunodeficiency virus (HIV) infection. This effect is brought about by its specific binding to Man-a(1-2)-Man unit(s) of high-mannose type glycan (HMTG) bound to HIV gp120. The recently determined crystal structure of AH suggests that three repeated segments (the residue numbers 1-38, 39-76 and 77-114 for segments 1, 2 and 3, respectively) form three sugar-binding pockets to accommodate Man-a(1-2)-Man units. The strong specific binding of AH to gp120 is considered to be due to multivalent interaction of the three sugar-binding pockets with three HMTGs of gp120 via the 'cluster effect' of lectin. It remains to be seen which residues of the sugar-binding pockets are essential for acceptance of Man-a(1-2)-Man. To identify the amino acid residues critical for anti-HIV effect, we performed mutational analysis. Mutant AHs were subjected to enzyme-linked immunosorbent assay testing for gp120-binding activity and to syncytium formation assay. As a result, it was revealed that Asp15, Tyr23, Leu25, Asn28 and Tyr32 in segment 1, Tyr61 in segment 2 and Tyr99 in segment 3 are essential for anti-HIV activity. The conserved residues, Asp53, Leu63, Asn66 and Tyr70, in segment 2 and, Asp91, Leu101, Asn104 and Tyr108, in segment 3 are also necessary. Furthermore, aromatic residues at positions 23 and 32 are required for creation of potency. These data will be useful for predicting the detailed mechanism of AH-Man-a(1-2)-Man/HMTG/gp120 interaction by computational analysis and for possible development of more potent microbicides for prevention of HIV transmission.

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Actinohivin, a Novel Anti-HIV Protein from an Actinomycete That Inhibits Syncytium Formation: Isolation, Characterization, and Biological Activities

Cited by 55 publications

References 22 publications

Mechanism by which the lectin actinohivin blocks HIV infection of target cells

Mechanism by which the lectin actinohivin blocks HIV infection of target cells

Endophytic actinomycetes: promising source of novel bioactive compounds

Actinohivin: specific amino acid residues essential for anti-HIV activity

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