Two members of the S-lac lectin gene family, LGALS1 and LGALS2, reside in close proximity on human chromosome 22q12-q13

S-lac lectins are a family of soluble lactose-binding proteins thought to function in the control of cell growth. We now report the chromosomal mapping of two members of the family, termed L-14-I and L-14-II, to the q12-q13 region of human chromosome 22, suggesting the possibility of a cluster of genes for lactose-binding proteins.

L-29, an endogenous lectin, binds to glycoconjugate ligands with positive cooperativity

The soluble mammalian lactose-binding lectins L-14-I and L-29 are both secreted and bind to oligosaccharides on laminin, a large extracellular matrix glycoprotein containing polylactosamine chains. Because of the potential functional significance of these lectin-laminin interactions, we compared quantitative aspects of L-14-I and L-29 binding to immobilized laminin using recombinant lectins labeled with 125I. We report that the concentration-dependent binding of L-29 exhibits positive cooperativity whereas binding of L-14-I does not. Cooperative binding of L-29 can also occur on glycoconjugate substrates other than laminin and is not dependent on cystine bond formation or aggregation in solution. L-29 contains repetitive sequences within the N-terminal domain not present in L-14-I. This domain is not required for binding activity, but is required for positive cooperativity. Though the precise mechanism of interaction of L-29 with laminin remains to be determined, it apparently results in assembly of a lectin aggregate on the substrate surface, which could have important functional consequences.

Sequence and specificity of a soluble lactose-binding lectin from Xenopus laevis skin

A 16-kDa lactose-binding lectin comprises 5% or more of the soluble protein in Xenopus laevis skin. This lectin is mainly localized in the cytoplasm of granular gland cells. In response to stress, the lectin along with a variety of toxic and antibiotic peptides are released onto the skin surface by holocrine secretion. We have purified the lectin, sequenced tryptic peptides using tandem mass spectrometry and Edman degradation, and isolated full-length cDNA using a deduced oligonucleotide. Comparison of the cDNA and peptide sequences revealed expression of at least two isolectins, which differ in sequence at only two or three amino acids. Comparison of cDNA with complementary message by ribonuclease protection confirmed expression in approximately equal abundance of two nearly identical messages. The major soluble lactose-binding lectin expressed in Xenopus muscle is composed of these same isolectins, but at 100-fold lower levels. Similarities and distinctions in sequence and carbohydrate-binding specificity indicate that this lectin is a novel member of a family of soluble lactose-binding lectins expressed in a wide range of vertebrate tissues.

Isolation and expression of a gene encoding L-14-II, a new human soluble lactose-binding lectin

In the course of screening a human hepatoma cDNA library with antibody raised against a mammalian lectin with subunit molecular weight of about 14,000, we detected a partial cDNA encoding a related but distinct protein that was possibly a homologous lectin (Gitt and Barondes, 1986). We here report the isolation and sequencing of a full-length cDNA for this protein from a HepG2 cDNA library. The cDNA encodes a protein with subunit molecular weight of 14,650. Expression of the coding sequence in Escherichia coli yields a product that binds to a lactose affinity column and is specifically eluted with lactose, confirming that this new protein is a lectin. Like its well studied relative, here called L-14-I, the new lectin, L-14-II, exists as a homodimer in solution. The two related human lectins have 43% amino acid sequence identity. The genomic DNA encoding L-14-II (LGALS2) contains four exons with similar intron placement to L-14-I (LGALS1); but the genomic upstream region, which contains several sequences characteristic of regulatory elements, differs significantly from L-14-I.

Blood group non-secretors have an increased inflammatory response to urinary tract infection

The aim of this study was to assess the possible relationship between secretor state and the inflammatory response to urinary tract infection (UTI). Girls with recurrent UTI were prospectively studied. They included 61 secretor and 23 non-secretor individuals with 604 episodes of recurrent UTI. The response to each UTI episode was measured as the levels of C-reactive protein, erythrocyte sedimentation rate and the body temperature as well as renal concentrating capacity and pyuria. The levels of C-reactive protein, erythrocyte sedimentation rate and the body temperature were significantly higher in non-secretors than in secretors (p less than 0.04). As a consequence, non-secretors had an increased probability of being assigned a diagnosis of acute pyelonephritis rather than asymptomatic bacteriuria (p less than 0.05). The higher inflammatory response in non-secretors was independent of the Gal alpha 1-4Gal beta adhesin expression of the infecting Escherichia coli strains. The increased inflammatory response to UTI in non-secretors might explain the accumulation of these individuals among patients with renal scarring.

A sialoglycoprotein complex linked to the microvillus cytoskeleton acts as a receptor for pilus (AF/R1) mediated adhesion of enteropathogenic Escherichia coli (RDEC-1) in rabbit small intestine

Escherichia coli strain RDEC-1 is an enteroadherent, diarrheagenic pathogen in rabbits that utilizes AF/R1 pili for initial (stage 1) adherence, but the host receptors for this adhesion are unknown. Here we demonstrate that RDEC-1 binds, via AF/R1 pili, to a specific rabbit ileal microvillus membrane glycoprotein receptor complex of subunits 130 and 140 kD. The binding involves sialic acid present on oligosaccharide moieties of the glycoprotein receptor. Furthermore, the microvillus membrane glycoprotein receptor complex appears to be associated with cytoskeletal components via brush border myosin 1. This newly described link between AF/R1 receptor and cytoskeletal components suggests that, in addition to this function in mucosal adherence, the pili may facilitate subsequent (second stage) close effacing attachment of RDEC-1 to the host epithelium by influencing cytoskeletal function.

Structure and bacterial receptor activity of a human salivary proline-rich glycoprotein

Using an overlay technique, we previously showed that the Gram-negative periodontal pathogen Fusobacterium nucleatum binds to a glycoprotein of Mr 89,000 (Prakobphol, A., Murray, P., and Fischer, S.J. (1987) Anal. Biochem. 164, 5-11) in the parotid saliva of some individuals. We now show that deglycosylation of the purified glycoprotein results in loss of receptor activity. Amino acid analysis of the protein core showed predominantly proline, glycine, and glutamic acid/glutamine, a characteristic of proline-rich glycoproteins (PRG). The amino terminus contained repeating sequences of Ser-Gln-Gly-Pro-Pro-Pro-Arg-Pro-Gly-Lys-Pro-Glu-Gly-Pro-Pro-Pro- Gln-Gly that had significant compositional and sequence homology to that encoded by exon 3 of the PRB3 gene. We analyzed the PRG oligosaccharides by a combination of mass spectrometry techniques and nuclear magnetic resonance spectroscopy. Twenty-seven highly fucosylated structures were identified. The most abundant was as follows (where Fuc is fucose). (formula; see text) To understand the structural basis of F. nucleatum binding, we screened glycolipids and neoglycolipids carrying carbohydrate structures related to those of the PRG for receptor activity; components with unsubstituted terminal lactosamine residues best supported adherence. Neoglycolipids constructed from PRG oligosaccharides were also receptors. Treatment with beta-galactosidase, but not alpha-fucosidase, abolished binding, suggesting that unsubstituted lactosamine units, including the 6-antenna of the major oligosaccharide, mediate F. nucleatum adherence.

Human breast carcinoma cDNA encoding a galactoside-binding lectin homologous to mouse Mac-2 antigen

A galactoside-binding lectin (Mr 29,000) has previously been identified in rat, mouse and human tissues. It is an abundant cell-surface component of inflammatory macrophages and their major non-integrin laminin-binding protein. It has also been found in the nucleus of other cell types. Here, we report the cloning and sequencing of a cDNA encoding the human galactoside-binding lectin from a breast carcinoma. The clone encodes a protein of 250 amino acids (aa) that is over 80% identical to its mouse and rat counterparts. The aa sequence has an N-terminal and a C-terminal, 'carbohydrate-binding', domain. The N-terminal domain consists of two parts. The first 41 aa are homologous to a transcription factor, i.e., the serum response factor. The adjacent part (aa 42-106) contains an unusual repeating element, that occurs seven times in human protein compared to nine times in rat and mouse. The C-terminal 'carbohydrate-binding' domain (aa 115-250) shows homology to L-14, another galactoside-binding lectin.

The receptor repertoire defines the host range for attaching Escherichia coli strains that recognize globo-A

Escherichia coli strains which colonize the human urinary tract express lectins specific for different members of the globoseries of glycolipids, e.g., globotetraosylceramide and globo-A. This study investigated the importance of globo-A expression for attachment to human uroepithelial cells, colonization of the urinary tract, and severity of urinary tract infection. The expression of receptor-active glycolipids by erythrocytes and epithelial cells was analyzed by thin-layer chromatography and bacterial overlay as well as by bacterial binding to those cells. The epithelial expression of the globo-A receptor was restricted to individuals of blood group A with a positive secretor state. Consequently, globo-A binding E. coli strains attached only to epithelial cells from these individuals. In contrast, globoside-recognizing strains attached in similar numbers to uroepithelial cells regardless of the ABH blood group and secretor state of the donor. The role of host receptor expression for infection with globo-A-specific E. coli was analyzed in 1,473 children with urinary tract infections. All those infected with strains exclusively expressing globo-A-specific adhesins were found to be of blood group A, compared with 45% in the population at large (P less than 0.006). The inflammatory response (fever, C-reactive protein, erythrocyte sedimentation rate) of individuals infected with these strains was lower than that in individuals with infections caused by globoside binding strains. The results demonstrate the importance of fitness between host receptors and bacterial adhesins for infection and suggest that minor receptor epitope differences have profound effects on the disease process.

Glycosphingolipid receptors for Pseudomonas aeruginosa

The binding of Pseudomonas aeruginosa to glycosphingolipids and to buccal and bronchial epithelial cells was analyzed. Three independently expressed specificities were found by bacterial binding to glycosphingolipids separated by thin-layer chromatography. All strains bound gangliotria- and gangliotetrasylceramide. All but one of the strains bound sialic acid-containing glycosphingolipids and lactosylceramide. The latter two specificities could be separated in that the lactosylceramide binding was retained and the sialic acid binding was suppressed when bovine serum albumin was used as a blocking agent in the thin-layer chromatography assay. The attachment to buccal epithelial cells, like the binding to sialylated compounds and lactosylceramide, was abolished by Formalin treatment of the bacteria, suggesting the importance of these specificities for cell adherence. In contrast, the binding to gangliotria- and gangliotetraosylceramide was retained by nonattaching Formalin-treated bacteria.

Soluble lactose-binding vertebrate lectins: a growing family

Extracts of rat intestine contain nine soluble lactose-binding lectins with subunit molecular weights ranging from 14,500 to 19,000 that were purified by affinity chromatography and ion-exchange chromatography. Two of them are either identical with or closely related to other known rat lectins. A third appears to be the isolated carbohydrate-binding C-terminal domain of a known lectin but lacks the N-terminal domain presumed to mediate a different function. The others have not been described previously. Among them, the major rat intestinal lectin, RI-H, and a related protein, RI-G, have N-terminal amino acid sequences with similarities to sequences found in other known rat lectins. Therefore, these results introduce new members of a growing family of these structurally homologous soluble lactose-binding proteins.

Binding specificities of wild-type and cloned Escherichia coli strains that recognize globo-A

In this study we compared the specificity for the globoseries of glycolipids of Escherichia coli expressing the O-negative, A-positive (ONAP) adhesin and clones transformed with the pap-like (prs or pap-2) gene cluster. Receptor-active glycolipids were identified by the ability of radiolabeled bacteria to bind to the glycolipids on thin-layer chromatogram plates. The ONAP adhesin and pap-like clones bound with high affinity to the globo-A and Forssman glycolipids. The ONAP strains did not recognize other glycolipids of the globoseries. In contrast, the pap-like clones also showed weak binding to globotriaosylceramide and reacted weakly with Gal alpha 1----4 Gal beta-latex beads. We suggest that the pap-like and ONAP adhesins recognize an epitope shared by the globo-A and Forssman structures, e.g., terminal GalNAc alpha 1----3 bound to Gal alpha 1----4Gal beta-containing glycolipids.

Novel polyfucosylated N-linked glycopeptides with blood group A, H, X, and Y determinants from human small intestinal epithelial cells

A novel type of N-linked glycopeptides representing a major part of the glycans in human small intestinal epithelial cells from blood group A and O individuals were isolated by gel filtrations and affinity chromatography on concanavalin A-Sepharose and Bandeiraea simplicifolia lectin I-Sepharose. Sugar composition, methylation analysis, 1H NMR spectroscopy of the underivatized glycopeptides and FAB-mass spectrometry and electron impact-mass spectrometry of the permethylated glycopeptides indicated a tri- and tetra-antennary structure containing an intersecting N-acetylglucosamine and an alpha (1----6)-linked fucose residue in the core unit for the majority of the glycans. In contrast to most glycopeptides of other sources, the intestinal glycopeptides were devoid of sialic acid, but contained 6-7 residues of fucose. The outer branches contained the following structures: Fuc alpha 1-2Gal beta 1-3GleNAc beta 1- (H type 1) Fuc alpha 1-2Gal beta 1-4GleNAc beta 1- (H type 2) Gal beta 1-4 (Fuc alpha 1-3)GlcNAc beta 1- (X) Fuc alpha 1-2Gal beta 1-4(Fuc alpha 1-3)GleNAc beta 1- (Y) GalNAc alpha 1-3(Fuc alpha 1-2)Gal beta 1-3GleNAc beta 1- (A type 1) GalNAc alpha 1-3(Fuc alpha 1-2)Gal beta 1-4GleNAc beta 1- (monofucosyl A type 2) GalNAc alpha 1-3(Fuc alpha 1-2)Gal beta 1-4 (Fuc alpha 1-3)GlcNAc beta 1- (trifucosyl A type 2) The blood group determinant structures were mainly of type 2, whereas glycolipids from the same cells contained mainly type 1 determinants. The polyfucosylated glycans represent a novel type of blood group active glycopeptides. The unique properties of the small intestinal glycopeptides as compared with glycopeptides of other tissue sources may be correlated with the specialized functional properties of the small intestinal epithelial cells.

P blood group and proneness to urinary tract infection in Japanese children

The globoseries of glycolipids are antigens in the P blood group system as well as epithelial cell receptors for uropathogenic Escherichia coli. The P1 blood group is overrepresented in Swedish girls with recurrent pyelonephritis. In this study, Japanese children with urinary tract infection (UTI) were analyzed for P blood group phenotype. Out of 26 children with recurrent UTI, 50% were of the P1 blood group compared to the 31% of P1 individuals in the Japanese population at large (p less than 0.05). Of children defined as having febrile UTI 62% were P1. The P1 blood group was thus significantly enriched (3.5 times) in the children with febrile UTI. These results support the hypothesis that individuals of blood group P1 run an increased risk for recurrent pyelonephritis.

Multiple soluble vertebrate galactoside-binding lectins

All vertebrates synthesize soluble galactoside-binding lectins. Many are expressed at high levels in the embryo and at lower levels in the adult, whereas others show an inverse pattern of expression. Most lectins tend to be concentrated in one or a number of specific cell types. In the past few years, the multiplicity of these lectins has become more apparent. For example, in Xenopus laevis 3 galactoside-binding lectins, 2 with a preference for alpha-galactosides, have been purified and partially characterized. They have subunit molecular weights ranging from 16,000 to 69,000. More detailed studies have been done in mammals. For example, rat lung contains 3 soluble beta-galactoside-binding lectins, RL-14.5, RL-18 and RL-29, with subunit molecular weights, respectively, of 14,500, 18,000 and 29,000. A notable feature of these lectins is that, although they all bind lactose about equally well, their carbohydrate-binding sites are actually quite different, as shown by competitive binding studies with a range of complex mammalian glycoconjugates. Human lung also contains several beta-galactoside-binding lectins, including HL-14, HL-22 and HL-29 with subunit molecular weights, respectively, of 14,000, 22,000 and 29,000. They too show significant differences in their carbohydrate-binding sites when analyzed with naturally occurring mammalian glycoconjugates. Sequencing of purified lectins and cDNA clones indicates that at least 4 distinct genes code for what appears to be a family of HL-14. Heterogeneity is also indicated from isoelectric focusing studies which resolve at least 6 acidic forms of HL-14 and 5 acidic forms of HL-29.(ABSTRACT TRUNCATED AT 250 WORDS)

Multiple soluble beta-galactoside-binding lectins from human lung

Soluble extracts of human lung contain three major beta-galactoside-binding proteins with apparent subunit molecular weights of 14,000 (HL-14), 22,000 (HL-22), and 29,000 (HL-29). HL-14 and HL-29 were abundant in all the specimens that we tested whereas HL-22 was abundant in some and very scarce in others. HL-14 could be resolved into at least six acidic forms by isoelectric focusing and HL-29 into at least five acidic forms by this procedure. In contrast, HL-22 is a basic protein. Other beta-galactoside-binding proteins with subunit molecular weights ranging from about 16,000 to 27,000 were also detected in lung extracts, but the possibility that they are degradation products cannot be excluded. HL-14 is very similar to a rat lung lectin (RL-14.5) in carbohydrate binding specificity and amino acid composition and reacts strongly with an antiserum raised against the rat lectin. HL-29 is similar to the rat lectin RL-29 in the same respects, but its carbohydrate binding specificity is somewhat different. Of the known rat lectins, HL-22 resembles RL-18 most closely in carbohydrate binding specificity, but it is significantly different in other properties and does not react with an antiserum raised against the rat lectin.

Structures of blood group glycosphingolipids of human small intestine. A relation between the expression of fucolipids of epithelial cells and the ABO, Le and Se phenotype of the donor

Small intestinal epithelial cells (enterocytes) were isolated from specimens obtained at operation from four human individuals with different blood group ABO, Lewis, and secretor phenotypes. The non-acid glycolipids were isolated and characterized by thin-layer chromatography, mass spectrometry, and proton NMR spectroscopy and for reactivity with monoclonal antibodies on thin-layer chromatograms. Monohexosylceramides and blood group ABH (type 1 chain) and Lewis glycolipids with 5-7 sugar residues were the major compounds present in all cases, and the expression of the major blood group glycolipids was in agreement with the ABO, Lewis, and secretor phenotype of the individual donors. Small amounts of more complex glycolipids with up to 10 sugar residues were identified by mass spectrometry in all cases. In addition, small amounts of lactotetraosylceramide, a blood group H-active triglycosylceramide with the structure of Fuc alpha 1-2Gal-Hex-Cer (where Fuc is fucose, Hex is hexose, and Cer is ceramide), and dihexosylceramides were identified in some cases. Globotriaosyl- and globotetraosylceramides were absent from the epithelial cells. Small amounts of Leb-active glycolipids in blood group OLe(a+b-), non-secretor and OLe(a-b-), secretor individuals as well as trace amounts of type 2 carbohydrate chain compounds in all individuals were detected by specific monoclonal antibodies.

Fecal excretion of intestinal glycosphingolipids by newborns and young children

Glycosphingolipids were shown to persist in human fecal excretions from birth up 2 years of age. The pattern of glycosphingolipids was dependent on blood group and secretor status of the child and changed dramatically during the first months of life. Perinatally cerebroside, hematoside and blood group active fucolipids were dominating among fecal glycolipids. From the time of weaning lactosylceramide abruptly became and then persisted as a dominating glycolipid although cerebroside, complex gangliosides and blood group active fucolipids could still be detected in feces even at 2 years of age.

Binding to galactose alpha 1----4galactose beta-containing receptors as potential diagnostic tool in urinary tract infection

The diagnosis of urinary tract infection is based largely on quantitative urine cultures. The usefulness of qualitative information about the virulence of the infecting bacteria remains undefined. Ability to attach to human uroepithelial cells is one characteristic of the pyelonephritogenic clones, as well as a virulence factor per se. The identification of host cell receptors for attaching bacteria has permitted the construction of agglutination tests for simple detection of bacterial binding properties. In the present study, the reactivity with Gal alpha 1----4Gal beta-latex [galactose alpha (1----4)galactose beta-latex] and globotetraosylceramide-latex was analyzed for strains from patients with acute pyelonephritis (n = 135), acute cystitis (n = 121), and asymptomatic bacteriuria (n = 119) and from the fecal flora of healthy children (n = 120) and compared with agglutination of human blood group P1 and p, as well as guinea pig, erythrocytes. The reactivity by bioassay and the receptor-specific assays were significantly correlated. The frequency of positive reactions among the pyelonephritis isolates was 78.5% with the globotetraosylceramide-latex reagent, compared with 41% for the cystitis isolates, 25% for the asymptomatic bacteriuria isolates, and 13% for the fecal isolates. The combination of bioassays and receptor-specific assays increased the resolution of adhesins. Thus, adhesins reacting with human p erythrocytes frequently were coexpressed with Gal alpha 1----4Gal beta-specific adhesins. The receptor-specific assays provide a refined reagent to resolve bacterial binding specificities, as well as a potential tool for clinical diagnosis.