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PubMed1985

Specific suppression of allograft rejection by trinitrophenyl (TNP)-induced suppressor cells in recipients treated with TNP-haptenated donor alloantigens.

Suppressor T cells, activated by injection of trinitrobenzene sulphonic acid in DA rats, prevented rejection of LEW kidney allografts in a donor-specific manner when adoptively transferred into syngeneic recipients along with trinitrophenyl (TNP)-haptenated LEW alloantigen. TNP-haptenated third-party alloantigen was ineffective in this system. The donor-specific suppression was dependent, too, on the haptenic portion of the chemically modified alloantigen. Hence, fluorescein isothiocyanate-donor antigen did not lead to suppression in the presence of TNP-reactive suppressor cells. There is, however, some crossreaction between DNP- and TNP-haptenated alloantigens so that TNP-reactive cells and DNP-donor antigen suppressed rejection whereas DNP-reactive cells and TNP-donor antigen did not prevent graft rejection. The suppressor cells were sensitive to cyclophosphamide and radiation but were resistant to hydrocortisone. They appear to be T cells of the OX8 (suppressor/cytotoxic) phenotype since they are positive for the pan T cell antigen W3/13, are Ig negative, and do not carry the W3/25 (T helper cell) marker. However, these suppressor cells are adherent to nylon wool. They are found mainly in the spleen, are detected there within 2 d of TNBS injection, and can persist for up to 12 wk. We propose that these cells are first-order T suppressor (Ts1) cells that act in the afferent phase of the response to a renal allograft.

Animals↗
PubMed2003

A temperature-sensitive allele of Drosophila sesB reveals acute functions for the mitochondrial adenine nucleotide translocase in synaptic transmission and dynamin regulation.

Rapidly reversible, temperature-sensitive (ts) paralytic mutants of Drosophila have been useful in delineating immediate in vivo functions of molecules involved in synaptic transmission. Here we report isolation and characterization of orangi (org), an enhancer of shibire (shi), a ts paralytic mutant in Drosophila dynamin. org is an allele of the stress sensitive B (sesB) locus that encodes a mitochondrial adenine nucleotide translocase (ANT) and results in a unique ts paralytic behavior that is accompanied by a complete loss of synaptic transmission in the visual system. sesB(org) reduces the restrictive temperature for all shi(ts) alleles tested except for shi(ts1). This characteristic allele-specific interaction of sesB(org) with shi is shared by abnormal wing discs (awd), a gene encoding nucleoside diphosphate kinase (NDK). sesB(org) shows independent synergistic interactions, an observation that is consistent with a shared pathway by which org and awd influence shi function. Genetic and electrophysiological analyses presented here, together with the observation that the sesB(org) mutation reduces biochemically assayed ANT activity, suggest a model in which a continuous mitochondrial ANT-dependent supply of ATP is required to sustain NDK-dependent activation of presynaptic dynamin during a normal range of synaptic activity.

Alleles↗
PubMed1993

Effect of single base substitutions at glycine-870 codon of gramicidin S synthetase 2 gene on proline activation.

The mutant gene coding for a proline-activating domain (grs2-pro) was cloned and sequenced from Bacillus brevis Nagano, BII-3 strain, which produces gramicidin S synthetase 2 defective in proline-activation. By comparison of the nucleotide sequence with the wild-type sequence, a single point mutation was found at the 2609th guanine, which was replaced with adenine, resulting in the change of the 870th glycine to glutamic acid. Homology search for the deduced amino acid sequence of grs2-pro gene revealed that the 870th glycine was conserved in adenylate-forming enzymes, and its flanking sequence was highly conserved among the aminoacyl adenylate-forming enzymes, such as antibiotic peptide synthetases: gramicidin S synthetase 1 and 2 (GS1, GS2), tyrocidine synthetase 1 (TS1), and delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine synthetase (ACVS); and other aminoacyl adenylation enzymes: alpha-aminoadipate reductase (LYS2), EntF, and AngR. On the other hand, this flanking sequence was not conserved in the other adenylate-forming enzymes lacking amino acid activation, such as acetyl-CoA synthetase, long-chain acyl-CoA synthetase, luciferase, and 4-coumarate CoA ligase. Single base substitutions at the 870th GGG codon were carried out by oligonucleotide site-directed mutagenesis. Four mutagenized clones were isolated, containing grs2-pro genes which exchange 870-Gly for alanine, valine, arginine, and tryptophan. The translated products from these clones could scarcely catalyze proline-dependent ATP-32PPi exchange reaction. The coil structure of 870-Gly region was lost in the mutants. These results suggest that the 870-Gly residue of grs2-pro protein is essential for aminoacyl-adenylation in the antibiotic peptide synthetase family.

Amino Acid Isomerases↗
PubMed1999

Amino acid changes in the repressor of bacteriophage lambda due to temperature-sensitive mutations in its cI gene and the structure of a highly temperature-sensitive mutant repressor.

The mutant cIts genes from seven different lambdacIts phages carrying tsU50, tsU9, tsU46, ts1, tsU51, tsI-22 and ts2 mutations were cloned in plasmid. The positions of these mutations and the resulting changes of amino acids in the repressor were determined by DNA sequencing. The first four mutations mapping in the N-terminal domain show the following changes: I21S, G53S, A62T and V73A, respectively. Of the three remaining mutations mapping in the C-terminal domain, cItsI-22 and cIts2 show N207T and K224E substitutions respectively, while the mutant cItsU51 gene carries F141I and P153L substitutions. Among these ts repressors, CIts2 having the charge-reversal change K224E was overexpressed from tac promoter in a plasmid and purified, and its structure and function were studied. Operator-binding studies suggest that the ts2 repressor is somewhat defective in monomer-dimer equilibrium and/or cooperativity even at permissive temperatures and loses its operator-binding ability very rapidly above 25 degrees C. Comparative studies of fluorescence and CD spectra, sulfhydryl group reactivity and elution behaviour in size-exclusion HPLC of both wild-type and ts2-mutant repressors at permissive and non-permissive temperatures suggest that the C-terminal domain of the ts2 repressor carrying a K224E substitution has a structure that does not favor tetramer formation at non-permissive temperatures.

Amino Acid Substitution↗
PubMed1995

Neuroimmunodegeneration: do neurons and T cells use common pathways for cell death?

In syndromes of pediatric neuroimmunodegeneration (NID), certain neurons and T cells degenerate and disappear during early development at an accelerated rate without alerting the peripheral immune cells. Current studies of some of these NID syndromes suggest that the primary cause of neuronal and T cell death is an imbalanced cytokine signaling system with a dysfunctional redox status, and that the loss of T cells and neurons may be secondary to impaired functions of their accessory supportive cells. These dysfunctions include inappropriate production of developmental cytokines, inadequate secretion of reductants, and disregulation of excitotoxic amino acid metabolism. Two examples of pediatric NID in humans are ataxia telangiectasia and pediatric human immunodeficiency virus infection. An animal model is retrovirus-induced T and neuronal cell loss in neonatal mice infected with a neuroimmunopathogenic mutant, ts1, of the Moloney murine leukemia virus. Because both thymic and neuronal components share many growth factors and developmental signals, it is likely that disregulation of these signals would lead to concomitant dysfunction of neuronal and thymic cells. In this review, we focus on the pathogenic mechanisms involved in these developmental NID syndromes with the objective of identifying common pathogenic factors and pathways responsible for the concurrent losses of both neurons and T cells.

Animals↗
PubMed1996

Detection of K-ras point mutations at codon 12 in pure pancreatic juice for the diagnosis of pancreatic cancer by PCR-RFLP analysis.

The present study was undertaken to detect K-ras point mutations at codon 12 in pure pancreatic juice (PPJ) for the diagnosis of pancreatic cancer (PC) using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. PPJ was collected through a cannula under a duodenal fiberscope from 26 patients with PC and 32 patients with chronic pancreatitis (CP). DNA was extracted from PPJ and was used as the template for PCR. Analysis of PPJ by PCR-RFLP with BstNI revealed that the incidence of K-ras point mutations at codon 12 was 81% (21/26) in patients with PC and 6% (2/32) in those with CP. With reference to the location of PC, the incidence of K-ras mutations was 79% (11/14) in the head, 86% (6/7) in the body, and 80% (4/5) in the tail of the pancreas. The incidence of K-ras mutants was 50% (1/2) in tumor size 1 (TS1; < or = 2.0 cm in size), 71% (5/7) in TS2 (2.1 to < or = 4.0 cm), 89% (8/9) in TS3 (4.1 to < or = 6.0 cm), and 88% (7/8) in TS4 (> 6.1 cm). These results suggested that analysis of K-ras point mutations at codon 12 in PPJ using the PCR-RFLP method is a promising new genetic test for the diagnosis of PC.

Adult↗
PubMed1987

Induction of transplantation tolerance in rats by spleen allografts. II. Evidence that W3/25+ T suppressor/inducer and OX8+ T suppressor/effector cells are required to mediate specific unresponsiveness.

The results presented in this report demonstrate that T cells, isolated from AGUS rats bearing long-term (WAG X AGUS)F1 spleen allografts adoptively transferred to irradiated AGUS recipients could not mediate the rejection of WAG hearts but rejected PVG. A hearts in acute fashion. Further, unresponsive T cells were able to suppress the capacity of adoptively transferred (40 X 10(6) normal T cells to reject WAG but not PVG.A heart allografts. We also studied the role of W3/25+ and OX8+ T cells subsets in the maintenance of unresponsiveness. Isolated W3/25+ or OX8+ unresponsive T cells were not able to mediate acute rejection, but were less effective in prolonging WAG allograft survival than the unresponsive whole T cell population, suggesting that both W3/25+ Ts1 and OX8+ Ts2 subsets were required for effective suppression in vivo. When, however, unresponsive W3/25+ T cells were infused simultaneously with normal OX8+ T cells, they could produce indefinite survival of WAG heart allografts. These results indicate that the unresponsive state induced by (WAG X AGUS)F1 spleen allografts transplanted to AGUS rats is maintained by the interaction of W3/25+ T suppressor/inducer and OX8+ T suppressor/effector cells.

Animals↗
PubMed1989

Alloreactive T suppressor cells in the rat. I. Evidence of three distinct subsets of splenic suppressor T cells resistant to cyclosporine.

In this study we examined the effect of cyclosporine on three distinct subsets of T suppressor (Ts) cells identified in a rat renal allograft model. Ts inducer (Ts1) cells having the CD4 marker are found in the spleens of DA rats undergoing acute rejection of LEW kidneys. Transducer (Ts2) and effector (Ts3) cells both carry the CD8 marker and are found in the spleens of long-term surviving DA rats bearing LEW kidney allografts made tolerant by donor-specific blood transfusions or by cyclosporine (in most cases). These latter cells are distinguished by their susceptibility to cyclophosphamide (CY), Ts2 cells being resistant while Ts3 cells are sensitive to CY. When Ts cells from DA rats undergoing acute graft rejection of LEW kidneys or bearing long-term-surviving LEW kidneys that had been treated with cyclosporine (10mg/kg/day) for 2 or 10 days, respectively, were adoptively transferred into lightly irradiated DA recipients, these cells were still able to specifically induce long-term survival of LEW kidneys. LEW kidney survival was not prolonged in DA rats given no cells or cells from rats treated with cyclosporine for 10 days. Thus it would appear that the three functional subsets of Ts cells demonstrated in this renal allograft model by adoptive transfer of spleen lymphocytes are not inhibited by cyclosporine, suggesting that this resistance of Ts cells to cyclosporine may be partly responsible for the immunosuppressive effect of this agent.

Animals↗
PubMed2006

T-reg mediated suppression of the allograft response in the draining lymph node.

We previously demonstrated that T-regs inhibit proliferation of graft-reactive T cells in the draining lymph node (DLN), suggesting that this site may be important for regulation. TCR transgenic mice (TS1) specific for viral hemagglutinin (HA) provided antigen-specific T cells for adoptive transfer into syngeneic Balb/c hosts bearing HA+ skin grafts. T-regs were obtained from (TS1xHA28)F1 mice known to have an expanded population of HA-specific T-regs. To determine whether the lymph node is an independent site of suppression, we developed a model in which donor antigen that migrates from the allograft to the DLN drives T-cell activation after graft removal. T-regs that did not encounter the allograft itself remained able to inhibit graft antigen-specific T-cell proliferation in the DLN. Alloantigen-induced regulation can occur in the absence of the graft. This finding identifies the DLN as a potentially critical site of regulation in the early posttransplant period.

Animals↗
PubMed2006

Roles for Drosophila mushroom body neurons in olfactory learning and memory.

Olfactory learning assays in Drosophila have revealed that distinct brain structures known as mushroom bodies (MBs) are critical for the associative learning and memory of olfactory stimuli. However, the precise roles of the different neurons comprising the MBs are still under debate. The confusion surrounding the roles of the different neurons may be due, in part, to the use of different odors as conditioned stimuli in previous studies. We investigated the requirements for the different MB neurons, specifically the alpha/beta versus the gamma neurons, and whether olfactory learning is supported by different subsets of MB neurons irrespective of the odors used as conditioned stimuli. We expressed the rutabaga (rut)-encoded adenylyl cyclase in either the gamma or alpha/beta neurons and examined the effects on restoring olfactory associative learning and memory of rut mutant flies. We also expressed a temperature-sensitive shibire (shi) transgene in these neuron sets and examined the effects of disrupting synaptic vesicle recycling on Drosophila olfactory learning. Our results indicate that although we did not detect odor-pair-specific learning using GAL4 drivers that primarily express in gamma neurons, expression of the transgenes in a subset of alpha/beta neurons resulted in both odor-pair-specific rescue of the rut defect as well as odor-pair-specific disruption of learning using shi(ts1).

Adenylyl Cyclases↗
PubMed1978

The acceptor for polar head groups of the lipid A component of Salmonella lipopolysaccharides.

We describe here experiments which determine at which stage in the lipid A biosynthesis the polar head groups 4-aminoarabinose, phosphorylethanolamine and 3-deoxy-D-manno-octulosonic acid are transferred to the diphosphorylated glucosamine backbone of the lipid A structure. Use was made of a conditional lethal mutant of Salmonella typhimurium (Ts1) which is defective in the synthesis of 3-deoxy-D-manno-octulosonic acid 8-phosphate and accumulates under nonpermissive conditions an underacylated lipid A intermediate [Lehmann, Rupprecht and Osborn (1977) Eur. J. Biochem. 76, 41-49]. Pulse-chase experiments, including a detailed analysis of radioactive pulse and chase products, demonstrated that this underacylated compound is a key intermediate in the lipid A synthesis. It can serve as direct acceptor for the incorporation of the polar head groups 4-aminoarabinose, phosphorylethanolamine and 3-deoxy-D-manno-octulosonic acid. On the basis of these findings some steps in the sequence of reactions involved in the lipid A biosynthesis are proposed.

Acetylglucosamine↗
PubMed2025

GT1 regulates maize sex determination by affecting the jasmonate pathway.

Maize (Zea mays L.) is a monoecious plant with male and female flowers physically separated on different inflorescences-the tassel and the ear. Maize sex determination is controlled by a series of complicated developmental signals. Here, we characterized an EMS-induced maize feminized tassel mutant,tasselsilk1 (tsk1), and identified GRASSY TILLERS1 (GT1) as the causative gene. Phenotypic analysis of tsk1 mutants revealed that pistils fail to abort in both the tassel and ear, resulting in long sterile silks in the tassel and the development of an extra small kernel from the lower floret in the ear. RNA-seq and CUT&Tag analysis indicated that GT1 functioned as a repressor for flower organ development by regulating the JA biosynthesis and signaling pathways, specifically by directly promoting the expression of TASSELSEED1 (TS1), ZmMYC2A, ZmMYC2B. Together, we identified a new allele of GT1 and proposed that GT1 functions through JA biosynthesis and signaling pathways to regulate sex determination in maize.

Zea mays↗
PubMed1986

Immunoadsorption of Cryptococcus-specific suppressor T-cell factors.

In the murine cryptococcal suppressor cell circuit, two different T-cell suppressor factors, TsF1 and TsF2, have been identified which specifically suppress the delayed-type hypersensitivity (DTH) response to cryptococcal culture filtrate antigen (CneF). TsF1 is produced by a first-order T suppressor (Ts1) cell population and suppresses the afferent limb of the DTH response, whereas TsF2 is produced by a second-order T suppressor (Ts2) cell population and suppresses the efferent limb of the cryptococcal DTH response. The objective of this study was to ascertain whether TsF1 or TsF2 could bind to cryptococcal antigen. To assess this, adsorption of TsF1 and TsF2 was performed with heat-killed Cryptococcus neoformans cells and by solid-phase immunoadsorption (SPIA) on columns containing cryptococcal antigens, i.e., CneF covalently bound to Sepharose 4B. The suppressive effect of TsF1 was removed by adsorption with intact heat-killed cryptococci and by SPIA on CneF-Sepharose 4B. The binding of cryptococcal TsF1 to the cryptococcal SPIA column was shown to be specific since Sepharose 4B columns either coupled with Saccharomyces cerevisiae mannan or blocked with glycine did not adsorb the suppressor activity. In contrast, the suppressive component of TsF2 did not bind to heat-killed cryptococci, CneF-Sepharose 4B, S. cerevisiae mannan-Sepharose 4B, or glycine-Sepharose 4B columns. These results, together with the finding that cryptococcal antigen, anticryptococcal antibody, and C1q-binding immune complexes were not demonstrated in either TsF1 or TsF2, establish that TsF1 and TsF2 can be differentiated on the basis of their affinity for cryptococcal antigen.

Animals↗
PubMed1988

Induction of antigen-specific T suppressor cells by soluble Paracoccidioides brasiliensis antigen.

In naturally acquired paracoccidioidomycosis, patients have depressed in vivo and in vitro cell-mediated immune (CMI) responses to Paracoccidioides brasiliensis antigen. In addition, it has been reported that these patients have significant levels of circulating paracoccidioidal antigen in their sera. The primary purpose of this investigation was to assess the effects of P. brasiliensis antigen on the CMI responses in a mouse model. On the basis of findings with other fungal agents, we predicted that circulating paracoccidioidal antigen may be inducing suppressor cells which modulate the CMI response. In this study, we show (i) that a soluble P. brasiliensis culture filtrate antigen (Pb.Ag) emulsified in complete Freund adjuvant and injected subcutaneously into mice induces reasonably high levels of delayed-type hypersensitivity (DTH) in CBA/J mice; (ii) that Pb.Ag elicits DTH reactions specific for P. brasiliensis when injected into footpads of immunized mice; and (iii) that an intravenous injection of Pb.Ag induces a population of lymph node and spleen cells which, upon adoptive transfer, suppress the afferent limb of the DTH response to paracoccidioidal antigen. The afferent suppressor cells can be detected in spleens as early as 5 days after Pb.Ag treatment, are present in significant numbers by 7 days in both spleens and lymph nodes, and are virtually absent by 14 days. In contrast, at 14 days after antigen injection, efferent suppressor cells were detected in spleens and lymph nodes. The Pb.Ag-induced afferent suppressor cells specifically inhibit the antiparacoccidioidal DTH response. They are nylon wool-nonadherent cells, and their activity is abrogated by anti-Thy-1 and complement treatment, indicating that they are T lymphocytes. The phenotype of these afferent suppressor T cells is L3T4+ Lyt-1+2- I-J+. The Pb.Ag-specific suppressor cells described in this paper are similar to the Ts1 cells in the azobenzenearsonate, 4-hydroxy-3-nitrophenyl acetyl, and cryptococcal models of suppression of the DTH response and to the afferent suppressor cells in the dinitrofluorobenzene contact sensitivity system.

Animals↗
PubMed1981

Characterization and mapping of temperature-sensitive division initiation mutations of Bacillus subtilis.

Two temperature-sensitive, filamenting mutants of Bacillus subtilis (ts1 and ts12) have been shown to be defective in the initiation of septation. Recombination index mapping showed that these mutations mapped in two different but closely linked genes. A third proposed initiation mutation, tms-12, probably maps in the same gene as ts12. Another proposed initiation mutation was not linked with these genes by transformation, indicating that there was a minimum of three genes involved in the initiation of division. PBS1 transduction mapping located these three genes close to the pyr cluster.

Bacillus subtilis↗
PubMed1990

Oligonucleotide probes for detection and differentiation of Staphylococcus aureus strains containing genes for enterotoxins A, B, and C and toxic shock syndrome toxin 1.

Different synthetic DNA nucleotide sequences were evaluated as gene probes for the specific detection and differentiation of Staphylococcus aureus strains encoding enterotoxins A (SEA), B (SEB), and C (SEC) and toxic shock syndrome toxin 1 (TSST-1). Identification of sequences unique to each toxin, based on knowledge of their nucleotide sequences, led to preparation of the specific 18-base oligonucleotide probes EA1 (encoding amino acids 177 to 182 of SEA), EB2 (encoding amino acids 105 to 110 of SEB), EC5 (encoding amino acids 125 to 131 of SEC1), and TS1 (encoding amino acids 160 to 166 of TSST-1). In colony blot hybridization analyses, these probes hybridized specifically with DNA from strains that produced the respective toxin serotypes. An excellent (greater than or equal to 93%) correlation between hybridization results (genotype) and toxin protein detection by an enzyme-linked immunosorbent assay (phenotype) was observed in the characterization of both reference and clinical strains of S. aureus for SEA, SEB, and TSST-1. A lower correlation (64%) for SEC reflected a lack of sensitivity in detecting toxin production. Our findings demonstrate that molecular DNA hybridization with synthetic oligonucleotide probes provides another approach for establishing the toxigenicity of S. aureus.

Amino Acid Sequence↗
PubMed2006

Development of real-time reverse transcriptase PCR assays to detect and serotype dengue viruses.

Serotyping dengue virus (DENV) from suspect human specimens is crucial for developing sound epidemiological control measurements early in the transmission season and for effective patient management. We modified DENV consensus D1 (mD1) and serotype-specific TS2 (mTS2) and redesigned serotype-specific TS1 (rTS1) and TS4 (rTS4) as described previously in the conventional capsid and premembrane gene (C-prM) protocol (R. S. Lanciotti, C. H. Calisher, D. J. Gubler, G.-J. Chang, A. V. Vorndam, J. Clin. Microbiol. 30:545-551, 1992). In addition, we designed two new sets of amplimers and probes, located at nonstructural protein 5 (NS5) and the 3' noncoding region (3'NC) of DENV. The NS5 protocol utilizes two flaviviral consensus outer amplimers (mFU1 and CFD2) and four dengue virus serotype-specific TaqMan fluorogenic probes. The 3'NC protocol uses two DENV consensus amplimers, DC10418 and CDC10564. The conventional gel-based, heminested detection method was adapted for the C-prM protocol for detecting and serotyping dengue viruses. In addition, we developed the real-time SYBR green I and postamplification melting temperature curve analysis for the mD1/TS and 3'NC protocols using identical amplification conditions. The NS5 amplimer/probe set was formulated as a one-tube, multiplex, real-time reverse transcriptase PCR for serotype identification. Three sets of amplimers and probes were verified for their specificity in tests with yellow fever, Japanese encephalitis, St. Louis encephalitis, and West Nile viruses; optimized against 109 DENV strains; and validated for detection of the virus in sera from two different panels of acute-phase human dengue serum specimens and one panel of virus isolates from dengue patients' serum specimens. Clinical evaluation by two separate laboratories indicated that the C-prM was more sensitive (100%) than the NS5 (91%) or the 3'NC (91%) protocol.

3' Untranslated Regions↗
PubMed2007

Enzymatic defects of the nsP2 proteins of Semliki Forest virus temperature-sensitive mutants.

We have analyzed the biochemical consequences of mutations that affect viral RNA synthesis in Semliki Forest virus temperature-sensitive (ts) mutants. Of the six mutations mapping in the multifunctional replicase protein nsP2, three were located in the N-terminal helicase region and three were in the C-terminal protease domain. Wild-type and mutant nsP2s were expressed, purified, and assayed for nucleotide triphosphatase (NTPase), RNA triphosphatase (RTPase), and protease activities in vitro at 24 degrees C and 35 degrees C. The protease domain mutants (ts4, ts6, and ts11) had reduced protease activity at 35 degrees C but displayed normal NTPase and RTPase. The helicase domain mutation ts1 did not have enzymatic consequences, whereas ts13a and ts9 reduced both NTPase and protease activities but in different and mutant-specific ways. The effects of these helicase domain mutants on protease function suggest interdomain interactions within nsP2. NTPase activity was not directly required for protease activity. The similarities of the NTPase and RTPase results, as well as competition experiments, suggest that these two reactions utilize the same active site. The mutations were also studied in recombinant viruses first cultivated at the permissive temperature and then shifted up to the restrictive temperature. Processing of the nonstructural polyprotein was generally retarded in cells infected with viruses carrying the ts4, ts6, ts11, and ts13a mutations, and a specific defect appeared in ts9. All mutations except ts13a were associated with a large reduction in the production of the subgenomic 26S mRNA, indicating that both protease and helicase domains influence the recognition of the subgenomic promoter during virus replication.

Acid Anhydride Hydrolases↗