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At least 19 recordsLinked to original sources
PubMed1992

The Crl protein activates cryptic genes for curli formation and fibronectin binding in Escherichia coli HB101.

Curli are thin, coiled, temperature-regulated fibres on fibronectin-binding Escherichia coli. The subunit protein of curli was highly homologous at its amino terminus to SEF-17, the subunit protein of thin, aggregative fimbriae of Salmonella enteritidis 27655 strain 3b, suggesting that these fibres form a novel class of surface organelles on enterobacteria. E. coli HB101 is non-curliated and unable to bind soluble, iodinated fibronectin. The phenotypically cryptic curlin subunit gene, csgA, in HB101 is transcriptionally activated by expressing the cytoplasmic Crl on a multicopy plasmid. Transcriptional activation of csgA by Crl was observed after growth at 26 degrees C but not at 37 degrees C, even though crl transcription was not thermoregulated. A deletion of the 39 carboxy-terminal residues abolished Crl activity, whereas a deletion of 10 residues at the C-terminus did not, implying that a region between residue 93 and 122 in the 132-amino-acid-residue large Crl protein is required for activating curli expression in E. coli HB101. crl is a normal housekeeping gene in E. coli and it is suggested that its gene product may either be a DNA-binding protein affecting chromatin structure as has been suggested for histone-like protein H1 or interact with specific regulatory protein(s) controlling transcription of genes required for curli formation and fibronectin binding.

Amino Acid Sequence↗
PubMed1992

Identification and characterization of a novel Bacillus thuringiensis delta-endotoxin entomocidal to coleopteran and lepidopteran larvae.

A new class of Bacillus thuringiensis delta-endotoxins, or insecticidal control proteins (ICPs), is defined by an apparently cryptic protein with a unique primary structure and novel entomocidal specificity for certain coleopteran and lepidopteran species. The discovery of a new group of ICPs will extend the use of this natural insecticide in integrated pest-management systems.

Amino Acid Sequence↗
PubMed1979

Characterization of a thermosensitive sporulation mutant of Bacillus subtilis affected in the structural gene of an intracellular protease.

A thermosensitive sporulation mutant (ts-15) of Bacillus subtilis has been isolated. This mutant when grown at the restrictive temperature (42 degrees C) is unable to sporulate, shows no intracellular protease activity and no protein turnover. These three traits were recovered in two revertants (ts-15R1 and ts-15R2) and were also transmitted together by transformation into the wild type. Immunological studies have shown that when ts-15 is grown at 42 degrees C it synthesizes a 'cryptic' protein with apparently the same antigenic properties as the wild type or as ts-15 mutant grown at the permissive temperature (30 degrees C). The intracellular proteases from the wild type and from ts-15 grown at 30 degrees C and 42 degrees C were completely purified and their properties were studied with respect to their molecular weights, substrate specificity, inhibition pattern, heat inactivation and antigenicity. The molecular weight of the enzyme from the wild type or ts-15 grown at 30 degrees C was 64000--65000 in the absence of sodium dodecylsulfate and 31000--32000 in the presence of sodium dodecylsulfate. It was assumed therefore that the active enzyme is formed from two similar subunits. However, the intracellular protease from ts-15 grown at 42 degrees C showed the same molecular weight of 32000--34000 in the presence or in the absence of sodium dodecylsulfate. On the basis of this experiment and others described in the paper we concluded that the mutation in ts-15 is most likely a point mutation in a structural gene of an intracellular protease and results in an inability to assemble the two subunits into an active form.

Bacillus subtilis↗
PubMed1978

Factor VIII/von Willebrand factor protein. Galactose a cryptic determinant of von Willebrand factor activity.

The normal Factor VIII/von Willebrand factor protein has the ability to agglutinate or aggregate normal platelets in the presence of ristocetin (von Willebrand factor activity). Removal of greater than 95% of the sialic acid from this protein by neuraminidase did not affect the von Willebrand factor or procoagulant activity. However, oxidation of the penultimate galactose of the asialo Factor VIII/von Willebrand factor protein with galactose oxidase resulted in a progressive loss of von Willebrand factor activity with no effect on procoagulant activity. Reduction of the 6-aldehydo intermediate by potassium borohydride caused full regeneration of von Willebrand factor activity. These studies confirm the identification of the intact penultimate galactose moiety as a critical determinant of von Willebrand factor activity.

Blood Coagulation Factors↗
PubMed2026

Progress towards a biotypic biomarker profile for amyotrophic lateral sclerosis-frontotemporal spectrum disorders.

Determining the optimal timing of disease-modifying therapies for neurodegenerative disorders will necessitate identification of when the underlying pathobiological process becomes active, well in advance of the point at which clinical manifestions appear. Phenoconversion, the emergence of clinically manifest syndomes, may be preceded by years to decades of silent pathobiological activity that can only be mapped by an array of biomarkers. ALS and FTD, traditionally identified as distinct clinical syndromes, are increasingly recognized to exist along a spectrum of clinical syndromes with shared genetic risk and shared underlying pathology. This clinicopathological spectrum is underpinned by cytoplasmic aggregation of TAR DNA-binding protein 43 (TDP-43) as the common neuropathological hallmark. In contrast, the majority of neuropathologically-defined frontotemporal lobar degeneration (FTLD) is associated with alterations in either TDP-43 metabolism (FTLD-TDP) or of the microtubule associated protein tau (FTLD-tau), with a smaller percentage associated with either autosomal dominant genetic mutations or impairments in the ubiquitin proteasome system. As the field of neurodegenerative disorders increasingly shifts towards the frameworks of a pathobiological definition of disease, there is a growing imperative to develop biomarkers that reflect the varied pathobiologies that underly these disorders, and to determine the sensitivity of such biomarkers to detect the presence of these pathobiologies before phenoconversion. To that end, an international workshop was convened in London, Canada in 2025 to review the evidence for existing or evolving biomarkers suitable for (1) the detection of either ALS or FTD pathobiology prior to phenoconversion and/or (2) predict phenoconversion in at risk individuals. Such biomarkers might be conceptualized as "biotypic biomarkers", capturing their ability to describe an underlying pathophysiology whilst being agnostic to the emergent clinical manifestations. Whereas no single biotypic marker is yet able to predict the emergence of ALS, FTD or their intersection, a multimodal approach to developing a biotypic biomarker profile holds promise for the detection of relevant pathobiological processes. The strength of such an approach would be augmented by also addressing issues of resiliency/susceptibility both in terms of genetic risk susceptibility profiles and developing sensitive biomarkers of genomic and cellular aging. By including such nontraditional markers of disease, a more robust picture of not only the degenerative process but also of those factors that might potentially mitigate or drive a heightened probability of disease can be derived.

cryptic exons↗
PubMedDate not supplied

Peptide immunization can elicit malaria protein-specific memory helper but not proliferative T cells.

We have studied the proliferative and helper T cell responses in mice to a malaria sporozoite vaccine candidate currently undergoing human trials. Following immunization of B10 (I-Ab) mice with the purified recombinant baculovirus-expressed Plasmodium falciparum circumsporozoite protein, draining lymph node cells were challenged in vitro with a series of overlapping synthetic peptides which span the construct. Surprisingly, only a single peptide from the protein was immunodominant in that it could reproducibly elicit a significant proliferative response from the immunized lymph node cells. This epitope, (NANP)n, is also the repetitive immunodominant B cell epitope of the protein. However, immunization of mice with synthetic peptides revealed at least 3 cryptic proliferative epitopes--epitopes not revealed by protein immunization--two of which represent conserved regions of the protein. While cryptic peptide-immunization did not elicit protein-specific proliferative T cells, it did reveal protein-specific helper T cells, as shown by an in vivo assay. Identification of "cryptic" epitopes not only for malaria but for other infectious diseases may aid vaccine design, especially in situations where subunit vaccines are sought.

Amino Acid Sequence↗
PubMed1992

The N-terminal 22 amino acids encoded by the gene specifying the major secreted protein of vaccinia virus, strain Lister, can function as a signal sequence to direct the export of a foreign protein.

Cells infected with vaccinia virus strain Lister secrete a polypeptide of approximate molecular weight 35,000 (35K) into the medium. Previous studies identified a cleavable, hydrophobic region of 17 amino acids in the 35K protein which could potentially function as a signal peptide to target the protein to the secretory pathway. Here we report the use of the expression-secretion signals derived from the 35K gene to direct export and secretion of a foreign protein. Vaccinia virus recombinants carrying the bacterial chloramphenicol acetyl transferase gene (cat) immediately downstream from the promoter and the N-terminal coding sequences of the 35K gene were constructed. Our studies show that the N-terminal 22 or 42 amino acids of the 35K protein direct efficient secretion of the CAT protein. However, due to a cryptic glycosylation site within CAT, glycosylated protein was secreted, which reduced enzymatic activity. Activity was restored in the presence of tunicamycin. Removal of the glycosylation site by site-directed mutagenesis abolished glycosylation with no effect on secretion, although CAT activity was again reduced, possibly due to an effect on the active site. The results presented here demonstrate the feasibility of using the promoter and the signal sequence of the 35K gene to generate recombinant viruses for overexpression and secretion of foreign proteins.

Animals↗
PubMed1992

Anaerobic growth of gonococci does not alter their Opa-mediated interactions with human neutrophils.

Gonococci grown anaerobically (anaerobic gonococci) in the presence of nitrite induce the expression of at least three novel outer membrane proteins (PANs 1 to 3). Although PAN 1 is expressed by gonococci during gonorrhea, the function of the PAN proteins remains unknown. In the absence of serum, gonococci possessing opacity-associated (Opa, formerly PII) outer membrane proteins adhere to, stimulate, and are phagocytically killed by human neutrophils. Gonococci lacking Opa proteins demonstrate none of these activities. We investigated whether the PAN proteins, or any other characteristics of anaerobic gonococci, altered the ability of nonpiliated, Opa+ or Opa- gonococci to adhere to, stimulate, or be phagocytically killed by neutrophils. The expression of Opa4 by strain F62, as determined by its relative mobility on sodium dodecyl sulfate-polyacrylamide gels, appeared to be unaltered by anaerobic growth, as seen previously (V. L. Clark, L. A. Campbell, D. A. Palermo, T. M. Evans, and K. W. Klimpel, Infect Immun. 55:1359-1364, 1987). Anaerobic and aerobic Opa+ gonococci adhered to and stimulated neutrophils to the same extent. Similarly, anaerobic and aerobic Opa- gonococci adhered to and stimulated neutrophils equally poorly. Finally, anaerobic and aerobic Opa+ gonococci were equally sensitive to phagocytic killing by neutrophils, while anaerobic and aerobic Opa- gonococci were equally resistant to killing. Thus, the role of Opa proteins in mediating the interactions of gonococci with human neutrophils appears unaltered by anaerobic growth, and the PAN proteins, or other cryptic properties of anaerobic gonococci, do not seem to modulate or mediate these phenomena.

Anaerobiosis↗
PubMed1992

Expression of an inducible enzyme II fructose and activation of a cryptic enzyme II glucose in glucose-grown cells of spontaneous mutants of Streptococcus salivarius lacking the low-molecular-mass form of IIIman, a component of the phosphoenolpyruvate:mannose phosphotransferase system.

We have reported previously that the phosphoenolpyruvate:mannose phosphotransferase system (mannose PTS) of Streptococcus salivarius, consisting of an Enzyme II mannose (EIIman) and two forms of Enzyme III mannose (IIIman) with Mr values of 38,900 and 35,200, respectively, concomitantly transports and phosphorylates mannose, as well as glucose and fructose. In this paper, we report the presence, in S. salivarius, of alternative specific fructose and glucose PTSs encoded by inducible and cryptic genes, respectively. Protein phosphorylation experiments conducted with [32P]phosphoenolpyruvate have allowed us to identify by SDS-PAGE and autoradiography the EII fructose (EIIfru) (Mr 57,500) and the EII glucose (EIIglc) (Mr 58,700). No proteins corresponding to IIIfru or IIIglc could be detected. EIIfru phosphorylated fructose on the C-1 position rather than, as with the constitutive mannose PTS, on the C-6 position. Growth on fructose resulted in the induction of EIIfru as well as an increase of 1-phosphofructokinase activity. Nevertheless, the genes encoding these proteins were independently regulated. Studies carried out with spontaneous mutants lacking the low-molecular-mass form of IIIman (mutants A37, G29 and B31) showed that EIIfru was expressed in glucose-grown cells of strains G29 and B31, but not in strain A37, whereas the cryptic gene encoding EIIglc was activated in all three mutant strains. The results obtained with the mutants suggest that the three spontaneous mutants were not all mutated on the gene encoding IIIman although all of them lacked IIIman.

Enzyme Induction↗
PubMed1992

Alternative topogenic signals in peroxisomal citrate synthase of Saccharomyces cerevisiae.

The tripeptide serine-lysine-leucine (SKL) occurs at the carboxyl terminus of many peroxisomal proteins and serves as a peroxisomal targeting signal. Saccharomyces cerevisiae has two isozymes of citrate synthase. The peroxisomal form, encoded by CIT2, terminates in SKL, while the mitochondrial form, encoded by CIT1, begins with an amino-terminal mitochondrial signal sequence and ends in SKN. We analyzed the importance of SKL as a topogenic signal for citrate synthase, using oleate to induce peroxisomes and density gradients to fractionate organelles. Our experiments revealed that SKL was necessary for directing citrate synthase to peroxisomes. C-terminal SKL was also sufficient to target a leaderless version of mitochondrial citrate synthase to peroxisomes. Deleting this tripeptide from the CIT2 protein caused peroxisomal citrate synthase to be missorted to mitochondria. These experiments suggest that the CIT2 protein contains a cryptic mitochondrial targeting signal.

Amino Acid Sequence↗
PubMed2026

A functional atlas of transposon-encoded products and their integration into host networks.

Transposable elements (TEs) are pervasive genomic components that propagate via self-encoded factors, yet the nature, regulation, and function of these factors remain largely unresolved. Here, we integrated extensive long- and short-read transcriptome data, regulatory network analyses, deep proteomics, and structural predictions to construct a comprehensive atlas of TE products in Arabidopsis. We show that TE expression is embedded within host regulatory circuits, with DNA methylation and transcription factors jointly shaping TE transcriptional activity. Proteomic analyses confirm the production of over a hundred of high-confidence TE-encoded proteins, and structure-guided analyses of the transcript-informed TE proteome predict previously uncharacterized structural folds, multimerization capacity, and host protein interaction potential. Structural alignments further uncover cryptic homologies between TE-encoded proteins and host factors, including cases of domestications and co-options. Together, our study reveals the functional integration of TEs into cellular pathways and underscores the role of TEs as active drivers of genome function and innovation.

Arabidopsis↗
PubMedDate not supplied

Characterization of two novel pre-B-cell lines (LK63 and LiLa-1): potential models of pre-B-cell differentiation.

In this report we describe two newly isolated pre-B acute lymphoblastic leukaemia cell lines. Both cell lines lack EBV as detected by the EBNA-1 gene probed Southern-blots. Neither cell line expressed the B-cell-specific CD20 antigen on the cell membrane. However surface expression of CD20 was induced by phorbol ester (TPA) on both LiLa-1 and LK63 cell lines. Other pre-B and B-cell lines, such as Reh, Nalm-1, and BALL-1 did not exhibit these changes in phenotype. Previous immunoprecipitation studies have noted that a broad 50-55 kD band co-precipitates with the characteristic 33-37 kD CD20 protein. We demonstrate that, while the 33-37 kD CD20 species was undetectable on resting LiLa-1 and LK63 cells, in each case a 50-55 kD protein was immunoprecipitated by the CD20 antibody. However, the failure to detect any cell surface CD20-associated antigen on the control cells by immunophenotyping indicated that the CD20 epitope of the 50-55 kD molecule was not expressed on the cell surface. Following exposure to TPA the 50-55 kD species was reduced over 48-72 h while the level of the p33-37 CD20 protein was increased. Northern-blot analysis showed that the 50-55 kD protein was not a cryptic form of CD20 as the uninduced cells contained no detectable CD20 mRNA. The decrease of the 50-55 kD protein and the acquisition of the mature CD20 molecule were paralleled by a decline in proliferative activity in both cell lines. As expression of CD20 by normal pre-B cells also coincides with the cessation of cell division and maturation towards a mature B-cell phenotype, these cell lines appear to represent models for a discrete stage of B-cell differentiation which may be valuable in defining the signals regulating pre-B-cell proliferation.

Antigens, CD↗
PubMed1992

Genetic organization and structural features of maranhar, a senescence-inducing linear mitochondrial plasmid of Neurospora crassa.

The nucleotide sequence of maranhar, a senescence-inducing linear mitochondrial plasmid of Neurospora crassa, was determined. The termini of the 7-kb plasmid are 349-bp inverted repeats (TIRs). Each DNA strand contains a long open reading frame (ORF) which begins within the TIR and extends toward the centre of the plasmid. ORF-1 codes for a single-subunit RNA polymerase that is not closely related to that encoded by another Neurospora plasmid, kalilo. The ORF-2 product may be a B-type DNA polymerase resembling those encoded by terminal protein-linked linear genetic elements, including linear mitochondrial plasmids and linear bacteriophages. A separate coding sequence for the terminal protein could not be identified; however, the DNA polymerase of maranhar has an amino-terminal extension with features that are also present in the terminal proteins of linear bacteriophages. The N-terminal extensions of the DNA polymerases of other linear mitochondrial plasmids contain similar features, suggesting that the terminal proteins of linear plasmids may be comprised, at least in part, of these cryptic domains. The terminal protein-DNA bond of maranhar is resistant to mild alkaline hydrolysis, indicating that it might involve a tyrosine or a lysine residue. Although maranhar and the senescence-inducing kalilo plasmid of N. intermedia are structurally similar, and integrate into mitochondrial DNA by a mechanism thus far unique to these two plasmids, they are not closely related to each other and they do not have any nucleotide sequence features, or ORFs, that distinguish them clearly from mitochondrial plasmids which are not associated with senescence and most of which are apparently non-integrative.

Amino Acid Sequence↗
PubMed1992

Characterization of a cryptic gene pair from Neisseria gonorrhoeae that is common to pathogenic Neisseria species.

A pair of genes, each of which produces in Escherichia coli a 20-kDa, periplasmically localized protein that cross-reacts with anti-rpoN monoclonal antibody, was isolated from Neisseria gonorrhoeae. Homologs of the two genes were detected in pathogenic Neisseria species but not in commensal species. These genes are designated cnp1 and cnp2 (cryptic neisserial protein).

Amino Acid Sequence↗
PubMed1991

Recognition of peptides that are immunopathogenic but cryptic. Mechanisms that allow lymphocytes sensitized against cryptic peptides to initiate pathogenic autoimmune processes.

Interphotoreceptor retinoid binding protein (IRBP) is a glycoprotein that localizes in the retina and induces inflammatory changes in this tissue in immunized animals. Certain IRBP-derived peptide determinants are also immunopathogenic, and we have previously shown that these determinants could be either immunodominant or cryptic. Lymphocytes sensitized against the cryptic peptides do not recognize whole IRBP in vitro, and yet these lymphocytes must recognize the protein in vivo to initiate the autoimmune pathogenic process. We have examined here two hypothetical explanations for this dissociation: 1) It is possible that when IRBP is processed in vitro, immunodominant peptide determinants compete with the cryptic ones and inhibit their interaction with the MHC molecules on the APC. This explanation was ruled out here by the finding that the immunodominant peptide 1179-1191 ("W10") did not inhibit the response to a cryptic one, 1158-1180 ("R4"), when added at equivalent and even moderately higher concentrations. 2) The second hypothesis proposes that the cryptic antigenic sites are not generated from IRBP by the APC in vitro, whereas enzymes in the retina digest the protein to yield fragments that generate these antigenic sites upon processing by the APC. In line with this hypothesis, we have found that cleavage of IRBP by certain endoproteinases (Asp-N, Glu-C, or V-8) produced molecules that were recognized in culture by lymphocytes sensitized to the immunopathogenic but cryptic peptide R4. This study, therefore, describes a putative Ag processing mechanism that results in IRBP recognition and, consequently, the initiation of an autoimmune process by lymphocytes sensitized against a cryptic peptide. Furthermore, experiments with R4 and other cryptic peptides have shown that cleavage fragments of up to 38 residues in length can be presented by APC, to stimulate lymphocytes sensitized against these peptides. No responses were stimulated, however, by fragments of 75 or more residues. The data thus provide new insights into the processing and presentation of cryptic peptide determinants by APC.

Amino Acid Sequence↗
PubMed1991

Evidence for shared epitopes within the 'naked' protein domains of human mucus glycoproteins. A study performed by using polyclonal antibodies and electron microscopy.

Polyclonal antibodies were raised in rabbits towards reduced subunits of human cervical mucus glycoproteins. The reduced subunits almost completely inhibited the antiserum, whereas the intact mucins and the heavily glycosylated fragments obtained after digestion of reduced subunits with trypsin (T-domains) caused only partial inhibition. Periodate oxidation of intact mucins, reduced subunits and T-domains caused no effect on the antibody response, and fragments obtained by more extensive proteolysis of the reduced subunits (P-domains) showed no inhibitory activity. By using electron microscopy, antibodies from T-domain-adsorbed antisera were revealed as bound to cervical mucin reduced subunits, either directly or with colloidal gold-Protein A. Binding sites (100-150 nm apart) were observed at the ends and at internal positions of the reduced subunits. We conclude that the antibodies do not recognize carbohydrate structures but are directed to two kinds of protein epitopes, one shared by whole mucins, reduced subunits and T-domains, and the other specific to the reduced subunit fragment. The latter epitopes are 'cryptic' and are probably shielded within folded protein domains stabilized by disulphide bonds. Human bronchial, cervical, gastric and salivary mucus glycoproteins share some of these cryptic epitopes.

Antibodies↗