The Biochemistry of Plant Lectins (Phytohemagglutinins)

Lis, Halina; Sharon, Nathan

doi:10.1146/annurev.bi.42.070173.002545

Cited by 974 publications

(251 citation statements)

References 139 publications

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“…Thus, the M. xanthus hemagglutinin appears to recognize a specific receptor that is not present on all erythrocytes in their native form. We have not attempted to modify the erythrocyte cell surfaces with enzymes such as trypsin or neuraminidase, which often unmask new receptors for hemagglutinins (22).…”

Section: Methodsmentioning

confidence: 99%

Myxobacterial hemagglutinin: A development-specific lectin of Myxococcus xanthus

Cumsky¹,

Zusman²

1979

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

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Fruiting body formation in the bacterium Myxococcus znthus consists of a temporal sequence of cellular aggregation and sporulation. During the period of cellular aggregation, a major new development-specific protein that has lectin-like activity is synthesized. This protein, called myxobacterial hemagglutinin (MBHA), was able to agglutinate sheep or guinea pig erythrocytes but not horse, ox, chicken, or human erythrocytes. MBHA was undetectable in extracts of vegetative cells, cells starved in liquid buffer, or in glycerol-induced cells. However, cells starved on a fruiting medium produced large amounts of MBHA (about 5% of protein synthesis), starting at about 6-8 hr of development. The protein accumulated in the soluble fraction of cells, reaching a peak of 1-2% of total protein at about the time when aggregation was completed. At later times the amount of MBHA present in the soluble fraction declined although synthesis continued. The hemagglutinating activity of MBHA could not be inhibited with simple sugars or aminosugars but could be inhibited with fetuin, a fetal calf serum glycoprotein. The Oglycosidically linked trisaccharide glycopeptide of fetuin was shown to be inhibitory by itself. The penultimate galactose of this glycopeptide was directly implicated in the inhibitory activity, because the inhibition byasialofetuin was reduced to 1/60th by periodate oxidation and to 1/15th after -galactosidase treatment. MBHA is an abundant biochemical marker of development in M. Xanthus. Ihe fact that it is a lectin suggests that it may play a role in cell-cell recognition or agglutination.Myxococcus xanthus is a Gram-negative bacterium which, because of its complex life cycle, is well suited for studies of development. When nutrients are depleted in a solid culture medium, cells reverse their outward movement and glide inward towards aggregation centers, forming mounds consisting of about 106 to 107 cells. The flat mounds then tighten into raised translucent structures. Within the mounds, the rodshaped cells convert to round or ovoid spores, which are resting cells resistant to many environmental factors. Mounds of mature myxospores are referred to as fruiting bodies. Thus, M. zanthus is an attractive microbial system for the study of cell-cell interactions during the aggregation process as well as cellular morphogenesis during sporulation.Cell surface carbohydrate binding or "lectin-like" proteins have been implicated in cell-cell interactions and intercellular adhesion in the cellular slime molds Dictyostelhum discoldeum (1) and Polysphondylium pallidum (2) as well as in other eukaryotic systems (3, 4). These proteins may act as molecular hooks directly facilitating cell-cell contact and recognition at the appropriate times during development or tissue differentiation (5-8). Lectins have been found in nondifferentiating cells as well (9-12). We therefore examined extracts of M. xanthus for a hemagglutinating activity. In this paper, we report that during fruiting body formation a major new development-s...

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Section: Methodsmentioning

confidence: 99%

Myxobacterial hemagglutinin: A development-specific lectin of Myxococcus xanthus

Cumsky¹,

Zusman²

1979

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

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“…Transformed cells brought into suspension with EDTA show an increased sensitivity to agglutination by plant lectins (14). Several aspects of the lectin agglutination phenomenon led us to propose recently that lectin agglutination might be superimposed on a spontaneous cellto-cell adhesive process that is more active in transformed than in normal cells (15).…”

mentioning

confidence: 99%

Rates of aggregation, loss of anchorage dependence, and tumorigenicity of cultured cells.

Wright¹,

Ukena²,

Campbell³

et al. 1977

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

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ABSTACr Ihe net rate of spontaneous aggregation of cells suspended with EDTA was measured for various cell types including spontaneous transformants and cells transformed with DNA and RNA viruses. The anchorage dependence as determined by growth in methyl cellulose and the tumorigenicity in vivo were also determined. All cells that had lost their anchorage dependency and were tumorigenic showed a high net rate of spontaneous adhesion. A31 was the only nontransformed cell line to have a high net rate of adhesion. Ihe net rate of spontaneous aggregation of cells is a quick and reliable index of tumorigenicity and offers a new approach to understanding the mechanisms of cell surface changes associated with transformation.One important approach to understanding the altered biology of malignant cells is comparison of the properties of cells grown in tissue culture with the characteristics of the same cells injected into experimental animals. Studies of this type have shown that malignant transformation is often associated with changes in the surface properties of cells (1, 2). Loss of postconfluence inhibition of cell division (3, 4), loss of contact inhibition of cell movement (5), and changes in surface antigenicity (6, 7) are thought to be related to such in vivo properties of tumors as loss of growth control, invasiveness, metastasis, and escape from immunological surveillance. In this regard, in vitro studies of cell adhesion have been of interest. It has been shown that transformation is associated with a decrease in cell adhesion to surfaces such as glass or plastic (8, 9). The effects of transformation on cell-to-cell adhesion are less clear, and different studies have produced conflicting results (10-13).Another surface property of cells that is affected by transformation is the ability to be agglutinated by plant lectins such as concanavalin A (Con A). Cultures used in these experiments were free of contamination by mycoplasma as judged by the uridine phosphorylase assay (24) and direct observation of cells by scanning electron microscopy.Aggregation Assay. The rate of aggregation of suspended cells was measured by the method described by Skehan and Friedman (25)

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“…Finally, the fact that Ia antigens are oligosaccharide in nature must be borne in mind when attempts are made to develop a relationship between Ia antigens and Ir genes and their role as recognition units. In this light, it should be recalled that carbohydrate determinants have been shown to be involved in a variety of recognition processes, such as sponge cell reaggregation (28), plant pathogen-host recognition (29), embryonic development (30), hemagglutination by plant lectins (30,31), plateletcollagen adhesion (30,32), and the removal from the circulation ofglycoproteins lacking their terminal sialic acid groups (30,33). The carbohydrate nature of the Ia specificities and their possible role in T-B cell collaboration may provide another example of the important role of carbohydrates as informational molecules.…”

Section: Inhibition Of Anti-ia3 By D-galactose and Related Sugarsmentioning

confidence: 99%

Ia antigenic specificities are oligosaccharide in nature: hapten-inhibition studies.

Clarke¹,

Parish²

1977

The Journal of Experimental Medicine

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The Ia (I region associated) antigenic system in the mouse is coded for by genes located within the H-2 complex and consists of at least four subregions (IA, IB, IE, AND IC) which code for a minimum of 21 (Ia. 1 to 21) specificities (1-3), although the existence of IB and IE subregions is now being questioned. These antigens were first detected on the surface of B lymphocytes and were subsequently found on macrophages, epidermal cells, and sperm cells (4). It is also apparent that some Ia specificities are present on either resting and activated T-blast cells (2-8). In addition, we have detected considerable amounts of Ia antigenic material in mouse serum and other tissue fluids, particularly after antigenic stimulation (8, 9). The current interest in this system stems from the close involvement of the I region in immune responses (1-3), especially with the recent demonstration that soluble factors of both antigen-specific and nonspecific nature which are involved in T-B cell collaboration (10, 11) and suppression (12), also carry Ia antigens. In this context, we have found that although B cells have a higher density of Ia antigens on their surface than T cells, the Ia antigens in serum are derived from T cells (9).Biochemical studies of the Ia specificities have proceeded along two lines. The cell surface Ia antigens of B cells have been extracted with detergents and were found to be glycoproteins with mol wt of approximately 30,000 (13,14). By contrast, our chemical studies of the serum Ia material suggest that it is predominantly (but not exclusively) carbohydrate in nature as the material has the following properties: (a) It is rich in carbohydrate and almost devoid of protein (15); (b) The Ia antigenicity is destroyed by neuraminidase and periodate, but not by pronase (15); (c) The Ia antigen binds to concanavalin A and Lotus lectins (15); (d) It is extracted and purified from serum by methods identical to those used to prepare oligosaccharides from human milk (15-17); (e) Its behaviour on paper and thin layer chromatography is similar to that of other oligosaccharides (15), and after acid hydrolysis of the purified Ia product a number of simple sugars have been detected by gas-liquid chromatography (manuscript in preparation). In this paper, we describe hapten inhibition studies using a variety of sugars that show that for at least four Ia antigens (Ia.1, Ia.3, Ia.7, and Ia.15) the antigenic specificity is defined by sugars.

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The Biochemistry of Plant Lectins (Phytohemagglutinins)

Cited by 974 publications

References 139 publications

Myxobacterial hemagglutinin: A development-specific lectin of Myxococcus xanthus

Myxobacterial hemagglutinin: A development-specific lectin of Myxococcus xanthus

Rates of aggregation, loss of anchorage dependence, and tumorigenicity of cultured cells.

Ia antigenic specificities are oligosaccharide in nature: hapten-inhibition studies.

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