DNA sequences specific for Caucasian G3m(b) and (g) allotypes: allotyping at the genomic level

Assignment of the G3m(g) and (b) correlative amino acid residues was performed at the genomic level by direct sequencing of DNA from nine Caucasian individuals. Two oligonucleotide primers were used for subclass-specific enzymatic amplification of a DNA segment comprising a major portion of the second and third constant region domains (C_H2 and C_H3) fo the human IgG3 heavy chain gene. Comparison of the sequences of amplified DNA from individuals serologically typed as homozygous for G3m(b) or G3m(g) or as heterozygous, G3m(b,g), revealed differences in the codons for the amino acid residues 291, 296, and 384. Proline, phenylalanine, and serine at these positions corresponded to G3m(b), and leucine, tyrosine, and asparagine to G3m(g). Heterozygotic individuals, typed G3m(b,g), displayed both the G3m(b) and G3m(g) codons at these three positions. The polymorphism at each of these three codons could be identified either as the appearance, or the loss, of recognition sites for the two restriction endonucleases, Nsp BII and Rsa I. This allowed the development of a polymerase chain reaction (PCR)-based assay permitting the distinction of G3m ^b and G3m ^g alleles by analyzing the electrophoretical mobility of the DNA fragments generated by digestion of the PCR-products with Nsp BII and Rsa I. Correspondence to: R. Grubb.     

Immunoglobulin allotypes of European populations. II.Gm, Am and Km(Inv) allotypic markers in Czechoslovakians.

The distribution of G1m(f,z,a, and x), G2m(n), G3m(b0, b1, b3, b5, c3, c5, g, s, t, and v), A2m(1 and 2) and Km(1) (formerly Inv[1]) allotypic determinants has been examined in a series of Czechoslovakian blood donors. The results indicate that Gmza;-;gvA2m1, Gmzax;-;gvA2m1, Gmf;n;bvA2m1 and Gmf;-;bvA2m1 are present in polymorphic frequencies. Further, 9 idiomorphic phenotypes were observed; however, without family data it was not possible to exactly define the majority of these. The observed frequencies of Gmza;g, Gmzax;g and Gmf;b and Km1 are similar to those observed previously in Czechoslovakians and similar to those observed in adjacent populations, though different from those observed in Western Europeans, primarily due to a higher frequency of Gmf;b in Czechoslovakians.     

Immunoglobulin Allotypes of European Populations. I. Gm and Km(Inv) allotypic markers in Hungarians.

The distribution of G1m(f, z, a, and x), G3m(b0, b1, b3, c3, c5, g, s, and t) and Km(1) (formerly Inv[1]) allotypic markers have been examined in 184 Hungarians. The results indicate that the frequency of the immunoglobulin haplotypes Gmza;g, Gmzax;g, Gmf;b and Km1 is similar to the frequencies observed in surrounding populations. In addition, Hungarians were found to be polymorphic for the Oriental haplotype Gmza;bst, and had low frequencies of other uncommon haplotypes. Our data indicate that about 5% of the Hungarian genome is of Oriental origin.     

A-tract polarity dominate the curvature in flanking sequences

It is well-known, but little understood, that the nucleotide sequences between phased A(4-6)-tracts (at 10-11 bp intervals) have only a slight effect on overall curvature. To explore this phenomenon, we have examined the gel-migration properties of sequences containing both A-tracts as well as G-tracts (i.e., sequences of the form G(n)C(m) or C(n)G(m), n + m > 4) in various relative positioning. We show that the composite bend of these sequences depends on their relative arrangement. When G-tracts are placed between two A-tracts, such that both tracts are repeated in phase to themselves (e.g., G(5)A(6)G(5)A(5)), or adjacent to the 3'-side of A-tracts (e.g., A(6)G(5)N(10)), they have minimal influence on the extent of bending of the composite sequence. When G-tracts are placed one helical repeat away from A-tracts (e.g., G(5)N(5)A(6)N(6)), or are adjacent only to the 5'-side of A-tracts (e.g., G(5)A(6)N(10)) their influence on the composite bend is larger. The differential behavior of AG- versus GA-tracts means that A-tracts influence their flanking sequences in a polar manner. Whereas they suppress, or make constant, the intrinsic bending characteristics of any sequence placed immediately 3' to them (and hence by definition any sequence placed between two phased A-tracts), sequences adjoining them on their 5'-side are free to modulate the overall curvature. We interpret these results as evidence for the dominant nature of the unique and nonuniform structure adopted by tracts of four adenines or more. The effects of A-tracts extend at least five base pairs into the adjoining 3' region. This is further evidence for the complexity of DNA structure and the inadequacy of simple nearest-neighbor models to explain all its manifestations.     

Influence of 5'-terminal cap structure on the initiation of translation of vaccinia virus mRNA

The ability of methylated vaccinia virus mRNA to bind to ribosomes derived from wheat germ of rabbit reticulocyte lysates has been studied after beta elimination, to remove the 5'-terminal m7G, and after "recapping" of beta-eliminated mRNA molecules using guanylyltransferase.guanine-7-methyltransferase complex from vaccinia virions. Removal of m7G from the mRNA results in significant loss of ability to bind to ribosomes and to simulate protein synthesis in vitro. Readdition of m7G, but not of unmethylated guanosine to the 5' end results in recovery of both of these functions. To evaluate the role of 2'-O-methylation of the penultimate ribonucleoside, mRNAs containing m7G-(5')pppA- and m7G(5')pppG- as well as m7G(5')pppAm- and m7G(5')pppGm- ends were synthesized in vitro at limiting S-adenosylmethionine concentrations by vaccinia virus cores. By comparing the cap sequences of ribosome-bound and unbound mRNAs, we concluded that 2'-O-methylation has at most a minor effect compared to that of m7G upon ribosome binding under in vitro conditions. Only at high input mRNA concentrations, at which competition might occur, was there some ribodomal enrichment of mRNAs containing a specific terminal structure, namely m7G(5')pppAm-.     

A Waldenstr?m's macroglobulin with anti-G3m(b1) antibody activity.

A human monoclonal macroglobulin (IgM, K) from a patient (KI) with Waldenstr?m's macroglobulinemia was shown to have antibody activity against a human IgG (Gm) allotype. In hemagglutination tests, only one anti-D serum with G3m(b0b1) reacted with macroglobulin KI. Antiglobulin specificity of macroglobulin KI was determined to be an anti-G3m(b1) antibody by hemagglutination inhibition tests. Fab fragments from macroglobulin KI could react with human IgG3 protein possessing G3m(b1), but Fc fragments could not react. Gm phenotype in IgG isolated from serum KI was determined to be Gm(a,z,g,b0,s,t,u). This is the first report of a Waldenstr?m's macroglobulin with antiglobulin specificity against a Gm allotype.     

Immunoglobulin allotypes in Jewish populations living in Israel and the United States

The ongoing interest in the interrelationships of Jewish populations justifies inclusion of the immunoglobulin allotypes in an ethnohistorical analysis. A total of 2,184 serum specimens obtained from unrelated Israeli Jewish and self-identified Milwaukee, WI, Jewish blood donors were classified as Ashkenazi, Sephardi, Asiatic, or North African and tested for G1m (a, x, z, and f), G3m (b0, b1, b3, b5, g), A2m (1 and 2), and Km (1). Selected sera were also tested for G3m (s, t, c3, c5). The estimated maximum likelihood Gm-Am haplotype frequencies were used in a heterogeneity chi-square analysis. The results indicate that there is less heterogeneity within Jewish populations from Europe, Middle East, and North Africa than in corresponding non-Jewish populations representing the same geographical areas. In order to avoid the hazards of a univariate focus, previously published data were incorporated into two additional analyses: 15 populations with information on 16 genetic loci and 24 populations with information on five genetic loci. Both sets of data were analyzed using principal-components and cluster analysis. In both sets of analyses, with the exception of the Yemenite Jews, Jewish populations grouped together. These analyses support the belief that Jewish populations appear to be derived from a common gene pool, and there has been some genetic drift and minimal gene flow with surrounding populations.     

Excision of 3-methylguanine from alkylated DNA by 3-methyladenine DNA glycosylase I of Escherichia coli.

Escherichia coli has two DNA glycosylases for repair of DNA damage caused by simple alkylating agents. The inducible AlkA DNA glycosylase (3-methyladenine [m3A] DNA glycosylase II) removes several different alkylated bases including m3A and 3-methylguanine (m3G) from DNA, whereas the constitutively expressed Tag enzyme (m3A DNA glycosylase I) has appeared to be specific for excision of m3A. In this communication we have reexamined the substrate specificity of Tag by using synthetic DNA rich in GC base pairs to facilitate detection of any possible methyl-G removal. In such DNA alkylated with [3H]dimethyl sulphate, we found that m3G was excised from double-stranded DNA by both glycosylases, although more efficiently by AlkA than by Tag. This was further confirmed using both N-[3H]methyl-N-nitrosourea- and [3H]dimethyl sulphate-treated native DNA, from which Tag excised m3G with an efficiency that was about 70 times lower than for AlkA. These results can explain the previous observation that high levels of Tag expression will suppress the alkylation sensitivity of alkA mutant cells, further implying that m3G is formed in quantity sufficient to represent an important cytotoxic lesion if left unrepaired in cells exposed to alkylating agents.     

Induction of microtubule-damage, mitotic arrest, Bcl-2 phosphorylation, Bak activation, and mitochondria-dependent caspase cascade is involved in human Jurkat T-cell apoptosis by aruncin B from Aruncus dioicus var. kamtschaticus

Exposure of human Jurkat T cells to aruncin B, purified from Aruncus dioicus, caused apoptosis along with microtubule damage, G(2)/M-arrest, Bcl-2 phosphorylation, Bak activation, mitochondrial membrane potential (Δψm) loss, cytochrome c release, activation of multiple caspases, and PARP degradation. Analyses by employing Bcl-2 overexpression and selective caspase inhibitors revealed that G(2)/M-arrest and Bcl-2 phosphorylation occurred prior to mitochondria-dependent activation of caspase-9, -3, and -8. The IC(50) values for human resting T cells, activated T cells, and Jurkat T cells were >60μg/ml, 49μg/ml, and 22μg/ml, respectively. These results demonstrate the apoptogenic activity of a novel microtubule-damaging agent aruncin B.     

Genetic and ecological study of aboriginal populations of northeastern Siberia. I. Gm-haplotypes and their frequency in 10 chukchi populations. Genetic structure of reindeer chukchi

G1m (z, a, x, f) and G3m (g, b0, b1, b3, b5, s, t) allotypes were tested in 1079 Chukchi inhabitants of interior Chukotka and adjacent Kamchatka. Genetic variation at this particular locus is provided by the presence of three haplotypes, namely, za;g, zax;g and za;bO35st, revealed with mean frequencies of 0.748, 0.089 and 0.154, respectively. Traces of Caucasian Gm (f;bO135) haplotype were observed in 9 of 10 populations studied. Judging from its frequency in the whole group (0.009), European admixture in Reindeer Chukchi did not exceed 1.3%. Analysis of covariance and variance matrices containing gene frequencies for 11 polymorphic loci revealed the aspects of genetic structure. Simultaneously, the action of systematic versus nonsystematic pressure was also evaluated and interpreted in the light of historical and ecological events.     

Isolation and characterization of rabbit anti-m3 2,2,7G antibodies.

Antibodies specific for intact 2,2,7-trimethylguanosine (m3 2,2,7G) were induced by immunization of rabbits with a nucleoside-human serum albumen (HSA) conjugate. Competition radioimmunoassay showed that the antibody distinguishes well between intact m3 2,2,7G and its alkali-hydrolysed form (m3 2,2,7G*). Antibody specificity is largely dependent on the presence of all three methyl groups in m3 2,2,7G: none of the less extensively methylated nucleosides m7G, m2G and m2 2,2G is able to compete efficiently with the homologous hapten. Little or no competition was observed with m1G, m1A, m6A, m5U and each of the four unmodified ribonucleosides. Binding studies with nucleoplasmic RNAs from Ehrlich ascites cells suggest that the antibody reacts specifically with the m3 2,2,7G-containing cap structure of the small nuclear U-RNAs (U-snRNAs). Thus the antibody should be a valuable tool for studying the role of the 5'-terminal regions of the U-snRNAs of eucaryotic cells.     

Antagonistic reaction of the periportal and perivenous zone in the rat liver after castration and estrogen treatment

Summary G6PDH and ME activity was determined biochemically in homogenates and demonstrated histochemically in cryostat sections of rat liver. Control animals were sham-operated, the male and female rats of the experimental groups were castrated. After castration groups of rats were treated with daily doses of 3 or 6 g/estradiolbenzoate for 21 days. The results show that in the controls there is a sex-dependent distribution pattern of the two enzymes; in males the rather low activity is mainly located in the periportal area, in females the higher activity is demonstrable in the perivenous area. After castration G6PDH activity (and to a lesser extent ME activity) increases, mainly in the periportal zone. Estrogen treatment results in the high activity of both enzymes, which are exclusively located in the perivenous zone. In the periportal zone no G6PDH or ME activity is demonstrable histochemically. This zone-typical effect of estrogen is interpreted in terms of the concept of Metabolic Zonation, according to which it is supposed that the NADPH generating enzymes in the perivenous area have a lipogenic function whereas the periportal activity contributes to bile acid production.Parts of this study were presented as an Inaugural Dissertation to the Medical Faculty of the University of FreiburgSupported by grants from the Deutsche Forschungsgemeinschaft (Sa 127/7) and the SFB 46 (Molgrudent)     

Regulation of AR mRNA translation in response to acute AR pathway inhibition

We report a new mechanism of androgen receptor (AR) mRNA regulation and cytoprotection in response to AR pathway inhibition (ARPI) stress in prostate cancer (PCA). AR mRNA translation is coordinately regulated by RNA binding proteins, YTHDF3 and G3BP1. Under ambient conditions m6A-modified AR mRNA is bound by YTHDF3 and translationally stimulated, while m6A-unmodified AR mRNA is bound by G3BP1 and translationally repressed. When AR-regulated PCA cell lines are subjected to ARPI stress, m6A-modified AR mRNA is recruited from actively translating polysomes (PSs) to RNA-protein stress granules (SGs), leading to reduced AR mRNA translation. After ARPI stress, m6A-modified AR mRNA liquid–liquid phase separated with YTHDF3, while m6A-unmodified AR mRNA phase separated with G3BP1. Accordingly, these AR mRNA messages form two distinct YTHDF3-enriched or G3BP1-enriched clusters in SGs. ARPI-induced SG formation is cell-protective, which when blocked by YTHDF3 or G3BP1 silencing increases PCA cell death in response to ARPI stress. Interestingly, AR mRNA silencing also delays ARPI stress-induced SG formation, highlighting its supportive role in triggering this stress response. Our results define a new mechanism for stress adaptive cell survival after ARPI stress involving SG-regulated translation of AR mRNA, mediated by m6A RNA modification and their respective regulatory proteins.     

Gm and Km immunoglobulin allotypes in Reindeer Chukchi and Siberian Eskimos

Summary Blood samples from 403 Reindeer Chukchi of inland Chukotka, and 100 samples from Chaplin Eskimos of the Chukot Peninsula were tested for G1m (z,a,x,f), G2m (n), G3m (g,b0,b1,b3,b5,s,t), and Km (1) allotypic determinants. An apparent affinity between the Chukchi and the Eskimos could be inferred from similar frequencies of the two common haplotypes, Gm^za;g and Gm^za;bst, and from very similar frequencies of the Km¹ allele. However, none of the Eskimos had Gm^zax;g, though it occurred at a low or moderate frequency in the five Chukchi populations studied. It is assumed that Chukchi can be distinguished from adjoining Eskimos by the same G1m (x) outlier, that has been considered as a taxonomic marker useful in differentiating between Eskimos and American Indians. Comparison of North Asian and North American populations with respect to the array and frequencies of Gm haplotypes and the Km¹ allele, supports the hypothesis of a nonrandom distribution of the Gm^za;bst and Km¹ on both sides of the Bering Strait.     

1-Methylguanosine deficiency of tRNA influences cognate codon interaction and metabolism in Salmonella typhimurium.

1-Methylguanosine (m1G) is present next to the 3' end of the anticodon (position 37) in tRNA(1,2,3,Leu), tRNA(1,2,3,Pro), and tRNA(3Arg). A mutant of Salmonella typhimurium lacks m1G in these seven tRNAs when grown at or above 37 degrees C, as a result of a mutation (trmD3) in the structural gene (trmD) for the tRNA(m1G37)methyltransferase. The m1G deficiency induced 24 and 26% reductions in the growth rate and polypeptide chain elongation rate, respectively, in morpholinepropanesulfonic acid (MOPS)-glucose minimal medium at 37 degrees C. The expression of the leuABCD operon is controlled by the rate with which tRNA(2Leu) and tRNA(3Leu) read four leucine codons in the leu-leader mRNA. Lack of m1G in these tRNAs did not influence the expression of this operon, suggesting that m1G did not influence the efficiency of tRNA(2,3Leu). Since the average step time of the m1G-deficient tRNAs was increased 3.3-fold, the results suggest that the impact of m1G in decoding cognate codons may be tRNA dependent. The trmD3 mutation rendered the cell more resistant or sensitive to several amino acid analogs. 3-Nitro-L-tyrosine (NT), to which the trmD3 mutant is sensitive, was shown to be transported by the tryptophan-specific permease, and mutations in this gene (mtr) render the cell resistant to NT. Since the trmD3 mutation did not affect the activity of the permease, some internal metabolic step(s), but not the uptake of the analog per se, is affected. We suggest that the trmD3-mediated NT sensitivity is by an abnormal translation of some mRNA(s) whose product(s) is involved in the metabolic reactions affected by the analog. Our results also suggest that tRNA modification may be a regulatory device for gene expression.     

Structural studies of a human gamma 3 myeloma protein (Goe) that binds staph protein A

The partial amino acid sequence of the Fc region of an unusual monoclonal immunoglobulin molecule (Goe), which had the allotypic markers Gm (b0, b3, b5, s, t, v), rarely encountered in Caucasians, was determined. Protein Goe was previously shown to belong to the gamma 3 subclass by antigenic typing, to possess a gamma 3-like hinge region and a gamma 1-like carboxy-terminal octadecapeptide, and to bind to staphylococcal protein A. The sequence of protein Goe resembled that of gamma 3 molecules except for the presence of tyrosine at position 296, alanine at position 339, and histidine and tyrosine at positions 435 and 436. It is of interest that histidine 435 appears to play an important role in binding to Staph protein A. Since tyrosine and phenylalanine at 296 and 300 are typical of G3m(g) molecules, whereas protein Goe is G3m(g-), this may correspond to the non-b1 allotypic marker. Of the numerous explanations to account for these findings, the most likely possibilities are that protein Goe is either a hybrid molecule or the product of a germ line gene representing the G3m s allotype, which is rare in Caucasians and common in Mongoloid populations. Support for the latter alternative is provided by the isolation from normal serum of a small amount of a protein having many of the properties of protein Goe.     

Molecular biology of β-lactam acylases

-Lactam acylases such as penicillin G acylases, penicillin V acylases and glutaryl 7-aminocephalosporanic acid acylases are used in the manufacture of 6-aminopenicillanic acid, 7-aminodesacetoxycephalosporanic acid and 7-aminocephalosporanic acid (7-ACA). Genetically-engineered strains producing 1050 U/g, 3200 U/g and 7000 to 10,000 U/I of penicillin G acylase, penicillin V acylase and glutaryl-7-ACA acylase, respectively, have been developed. The penicillin G acylase studied to date and the glutaryl-7-ACA acylase from Pseudomonas sp. share some common features: the active enzyme molecules are composed of two dissimilar subunits that are generated from respective precursor polypeptide; the proteolytic processing is a post-translational modification which is regulated by temperature; and the Ser residue at the N-terminus of the -sub-unit (Ser²⁹⁰; penicillin G acylase numbering) is implicated as the active site residue. Protein engineering, to generate penicillin G acylase molecules and their precursors with altered sequences, and the structure-function correlation of the engineered molecules are discussed.The authors are with Research and Development, Hindustan Antibiotics Ltd, Pimpri, Pune 411 018, India;     

7-Methyl-guanosine and efficiency of RNA translation.

Brome mosaic virus RNAs 3 and 4 were chemically modified to remove the terminal 7-methyl-guanosine (m7G) structure, and the modified RNAs were tested for their messenger activity in a cell-free system derived from wheat embryo. Amino acid incorporation and ribosome-binding data show that removal of m7G results in reduction, but not complete abolition, of the messenger activity of the RNA. This suggests that the function of m7G may be related to efficient translation of messenger RNA. Possible involvement of other structural factors in RNA translation is discussed.