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PubMed1988

Wolffish antifreeze protein genes are primarily organized as tandem repeats that each contain two genes in inverted orientation.

The antifreeze protein genes of the wolffish (Anarhichas lupus) constitute a large multigene family of 80 to 85 copies, which can be classified into two sets. One-third of the genes were linked but irregularly spaced. The other two-thirds were organized as 8-kilobase-pair (kbp) tandem direct repeats that each contained two genes in inverted orientation; DNA sequence analysis suggests that both genes are functional. Except for a single region specific to each gene, the genes and their immediate flanking sequences were 99.2% identical. This degree of identity ended soon after a putative transcription termination sequence; as the 3' ends of the genes were only 1.3 kbp apart, these sequences might confer mutual protection from interference by transcriptional runoff. A Southern blot of wolffish DNA restricted with enzymes that do not cut within the tandem repeats indicated that the repeats were clustered in groups of six or more. The organization of antifreeze protein genes in the wolffish was very similar to that in the unrelated winter flounder, which produces a completely different antifreeze. This similarity might reflect common dynamics by which their progenitors adapted to life in ice-laden sea water.

Amino Acid Sequence↗
PubMed1986

[Structure of long terminal repeats of transcriptionally active and inactive copies of the mobile dispersed gene MDG3 in Drosophila melanogaster].

The nucleotide sequences of long terminal repeats (LTRs) and adjacent regions are determined in the transcribed and non-transcribed variants of a mobile dispersed genetic element MDG3. MDG3 is similar to other mdg elements. A 4 bp duplication of the host DNA is generated upon its integration. MDG3 is flanked by a 5 bp inverted repeat. The length of the LTRs varies in different MDG3 variants, the difference being connected mainly with duplications of certain sequences in U3 and R regions. The copies with 267 bp LTR are the most abundant ones and perfectly conservative in their primary structure. They are transcribed in 67J25D cell culture and are not transcribed in Kc cell line, where another variant with LTR length 293 bp is transcriptionally active. S1-mapping of transcription initiation and termination sites has demonstrated that in both MDG3 variants they are situated in the same positions, and the LTR itself may be subdivided into U3, R and U5 regions, like retroviral LTRs. Possible factors involved in the regulation of mdg transcription are discussed.

Animals↗
PubMed1985

Orthopoxvirus DNA: a comparison of restriction profiles and maps.

Characteristic DNA endonuclease digest fragment electropherograms and restriction site maps permitted differentiation and genome structure analysis of 38 orthopoxviruses that included isolates of monkeypox virus from humans and animals, monkeypox white variants, variola, vaccinia, ectromelia, Tatera (gerbil) and raccoon poxviruses, and cowpox and camelpox viruses. HindIII cleavage sites mapped on the 38 virus genome DNAs plus SmaI, BglI, SacI, KpnI, XhoI, and SalI maps for variola (Harvey) and monkeypox (Copenhagen) virus DNAs were derived essentially by cross-hybridizations with monkeypox, vaccinia, and variola virus-cloned DNA restriction fragments, thus digest fragments could be assigned homologous regions on previously established genome maps. Salient of our observations, the DNA HindIII maps correlated to a high degree, but variations in middle and especially terminal DNA region cleavage sites provided a basis for discerning species, strains and variants. The extent of the inverted terminal repetitions (ITRs) for 37 DNAs were determined with HindIII, PvuI, SalI, and ClaI, plus nine more restriction enzymes for Bangladesh variola virus DNA by hybridizations with either the terminal tandemly repeated 70-bp segment or an EcoRI-PvuI near hairpin-end 75-bp segment from WR vaccinia virus. The opposite terminal regions of variola DNA were considerably asymmetrical compared to the large symmetrical ITRs of the other species examined. An apparent DNA inversion and concurrent deletion (1 kbp) with subsequent repair of DNA to original structure was suggested from right terminal region maps of four viruses chosen from a variola virus passage series in monkeys. Correlative with virus geographic distribution, two strains of monkeypox virus, each containing two variants, were differentiated by DNA profiles of isolates from smallpox-like disease (SLD) patients of the African rainforest region. The DNAs of five monkeypox viruses isolated from laboratory and zoo animals resembled most DNAs from SLD monkeypox viruses from Sierra Leone. A poxvirus from an American raccoon contained 40% DNA that did not cross-hybridize with orthopoxvirus DNA probes. The DNAs of recent isolates from a gerbil and from a camel each mapped as unique African orthopoxvirus species and differed from variola virus.

Animals↗
PubMed2005

Launching of the yeast 20 s RNA narnavirus by expressing the genomic or antigenomic viral RNA in vivo.

20 S RNA virus is a persistent positive strand RNA virus found in Saccharomyces cerevisiae. The viral genome encodes only its RNA polymerase, p91, and resides in the cytoplasm in the form of a ribonucleoprotein complex with p91. We succeeded in generating 20 S RNA virus in vivo by expressing, from a vector, genomic strands fused at the 3'-ends to the hepatitis delta virus antigenomic ribozyme. Using this launching system, we analyzed 3'-cis-signals present in the genomic strand for replication. The viral genome has five-nucleotide inverted repeats at both termini (5'-GGGGC... GCCCC-OH). The fifth G from the 3'-end was dispensable for replication, whereas the third and fourth Cs were essential. The 3'-terminal and penultimate Cs could be eliminated or modified to other nucleotides; however, the generated viruses recovered these terminal Cs. Furthermore, extra nucleotides added at the viral 3'-end were eliminated in the launched viruses. Therefore, 20 S RNA virus has a mechanism(s) to maintain the correct size and sequence of the viral 3'-end. This may contribute to its persistent infection in yeast. We also succeeded in generating 20 S RNA virus similarly from antigenomic strands provided active p91 was supplied from a second vector in trans. Again, a cluster of four Cs at the 3'-end in the antigenomic strand was essential for replication. In this work, we also present the first conclusive evidence that 20 S and 23 S RNA viruses are independent replicons.

DNA, Viral↗
PubMed1995

Frequency and distribution of DNA uptake signal sequences in the Haemophilus influenzae Rd genome.

The naturally transformable, Gram-negative bacterium Haemophilus influenzae Rd preferentially takes up DNA of its own species by recognizing a 9-base pair sequence, 5'-AAGTGCGGT, carried in multiple copies in its chromosome. With the availability of the complete genome sequence, 1465 copies of the 9-base pair uptake site have been identified. Alignment of these sites unexpectedly reveals an extended consensus region of 29 base pairs containing the core 9-base pair region and two downstream 6-base pair A/T-rich regions, each spaced about one helix turn apart. Seventeen percent of the sites are in inverted repeat pairs, many of which are located downstream to gene termini and are capable of forming stem-loop structures in messenger RNA that might function as signals for transcription termination.

Base Composition↗
PubMed2000

Very strong correlation between dominant negative activities of mutant thyroid hormone receptors and their binding avidity for corepressor SMRT.

The syndrome of resistance to thyroid hormone (RTH) is an inherited disorder involving a mutation of the thyroid hormone receptor (TR) gene. Mutant (m) TR inhibits wild-type (wt) TR functions in a dominant negative manner, and this dominant negative effect (DNE) is a crucial factor in RTH pathogenesis. The molecular mechanism of the DNE is still unclear, although several possibilities (including competition between wt- and mTRs at the T(3) response element (TRE), sequestration of TR-associated protein(s) and titration out of functional TR) have been considered. Here we report that the DNE of mTRs is strongly correlated with their binding avidity for the retinoid X receptor (RXR), and especially for corepressor SMRT (silencing mediator for retinoid and thyroid hormone receptor), but not for the nuclear receptor corepressor, NCoR. The DNE of six natural TRs and four artificially constructed mTRs was assayed using a TR reporter gene containing TRE-DR4 (DR=direct repeat), TRE-pal (pal=palindrome) or TRE-lap (lap=inverted palindrome) in CV1 cells treated with 10 nM T(3). Of the mTRs examined, F451X (with a carboxy-terminal 11-amino-acid truncation) identified in a patient with RTH exhibited the strongest DNE on all TREs. The binding affinities between mTRs and corepressors SMRT or NCoR were quantified using a two-hybrid interference assay system consisting of VP16-TR(LBD) (LBD=ligand binding domain) and Gal4(DBD)-SMRT (DBD=DNA binding domain), or Gal4(DBD)-NCoR respectively, together with the Gal4 reporter gene. In this assay, VP16-TR(LBD) and Gal4(DBD)-SMRT (or Gal4 (DBD)-NCoR) interact with each other and trans-activate the Gal4 reporter gene. When an equal amount of mTR is coexpressed, it reduces the transcriptional activity of the reporter gene, depending on its binding avidity for a corepressor. A very strong correlation was observed between the SMRT-binding activity and the potency of the DNE among six natural mTRs and also among all mTRs, including four artificially constructed ones. The relationship between NCoR and DNE, however, was not significant. When we assayed the binding avidity of mTRs for RXR by using a two-hybrid assay system consisting of Gal4(DBD)-RXR(LBD) and VP16-TR(LBD), a significant correlation between DNE and binding avidity for the RXR was also observed. These results suggest that a corepressor plays an important role in DNE pathogenesis.

Analysis of Variance↗
PubMed2004

Use of the quantitative fluorescent-PCR assay in the study of fetal DNA from micromanipulated transcervical samples.

AIM: The purpose of this study was to evaluate the validity of the combined use of micromanipulation and quantitative fluorescent (QF)-PCR assay for the identification of fetal elements in transcervical cell (TCC) samples collected in early pregnancy. METHODS: TCC samples were obtained by intrauterine lavage (IUL) in 113 pregnant women who were between 7 and 12 weeks pregnant before termination of pregnancy. All IUL samples were screened under an inverted microscope, at which time the isolation of fetal cells by micromanipulation was attempted. QF-PCR assay, using 9 small tandem repeat (STR) markers for chromosomes 13, 18, 21, X, and Y, was performed in all specimens to identify fetal cells in TCC samples and the corresponding placental tissue and blood specimens. TCC samples from male fetuses in which either the micromanipulation or QF-PCR analysis were unsuccessful, were studied with fluorescent in situ hybridization (FISH), using probes for X and Y chromosomes. RESULTS: Isolation of supposed fetal material from IUL samples was carried out by means of micromanipulation in 93 cases (82.3%), where discernible chorionic villous filaments or cell clumps of probable trophoblastic origin were present. The QF-PCR analysis was performed in all 93 IUL samples and paternal peaks could be documented in 88 cases (94.6%) thus confirming the presence of fetal cells. Thirteen cases negative to micromanipulation and derived from male fetuses and four male cases not informative with QF-PCR analysis, after micromanipulation, were then tested with FISH assay using probes for sexual chromosomes. In six samples, rare (2-3%) male fetal cells were detected. Considering the combined results obtained from QF-PCR and FISH assays, the overall fetal sexing was correct in 83.2% of cases (94 of 113). CONCLUSION: This study provides evidence that fetal cells are present in a high proportion of IUL samples. Micromanipulation appears to be an extremely efficient method for the isolation of trophoblastic elements. This study also confirms the potential of IUL as a possible alternative to the traditional prenatal diagnostic procedures for the recovery of fetal cells in precocious stage of gestation, and validates the combination of the isolation of such fetal elements by means of micromanipulation and analysis with the QF-PCR assay for the identification of the most frequent prenatal chromosomal aneuploidies.

Cervix Uteri↗
PubMed2000

Molecular characterization of the leucine plasmid from Buchnera aphidicola, primary endosymbiont of the aphid Acyrthosiphon pisum.

The complete sequence of the leucine plasmid of Buchnera aphidicola from the aphid Acyrthosiphon pisum (pLeu-BAp) is reported. Its gene organization was concordant with those of other leucine plasmids of Buchnera from aphids of the Aphidini and Macrosiphini tribes. Three inverted repeats are present in pLeu-BAp. Two of them are also present in pLeu from the family Aphididae: (i) SIR1, located downstream the leucine operon, resembles a rho-independent terminator of transcription, and (ii) LIR1, located upstream of the leucine operon, is suggested to be involved in transcription termination or messenger stability. The third, located near the putative ATGC repeats involved in the origin of replication, is specific in aphids of the Macrosiphini tribe. Phylogenetic analyses based on sequences of leuA, leuB, leuC, leuD, repA1 and ORF1 showed a closer relationship between Buchnera (A. pisum) and Buchnera (Diuraphis noxia). However, tree topologies indicate that the split between both aphid species took place soon after the formation of the Macrosiphini lineage.

Animals↗
PubMed1995

Staphylococcus aureus penicillin-binding protein 4 and intrinsic beta-lactam resistance.

Increased levels of production of penicillin-binding protein PBP 4 correlated with in vitro acquired intrinsic beta-lactam resistance in a mutant derived from a susceptible strain of Staphylococcus aureus, strain SG511 Berlin. Truncation of the PBP 4 C-terminal membrane anchor abolished the PBP 4 content of cell membrane preparations as well as the resistance phenotype. A single nucleotide change and a 90-nucleotide deletion, comprising a 14-nucleotide inverted repeat in the noncoding pbp4 gene promoter proximal region, were the only sequence differences between the resistant mutant and the susceptible parent. These mutations were thought to be responsible for the observed overproduction of PBP 4 in the intrinsically beta-lactam-resistant mutant. The pbp4 gene was flanked upstream by the open reading frame abcA, coding for an ATP-binding cassette transporter-like protein showing similarities to eukaryotic multidrug transporters and downstream by a glycerol 3-phosphate cytidyltransferase (tagD)-like open reading frame presumably involved in teichoic acid synthesis. The abcA-pbp4-tagD gene cluster was located in the SmaI-D fragment in the S. aureus 8325 chromosome in close proximity to the RNA polymerase gene rpoB.

ATP-Binding Cassette Transporters↗
PubMed1983

Nucleotide sequences of feline sarcoma virus long terminal repeats and 5' leaders show extensive homology to those of other mammalian retroviruses.

The nucleotide sequences of the Gardner-Arnstein feline sarcoma virus (FeSV) long terminal repeat and the adjacent leader sequences 5' to the viral gag gene were determined. These were compared with homologous portions of Synder-Theilen FeSV and with previously published sequences for Moloney murine sarcoma virus and simian sarcoma virus proviral DNA. More than 75% of the residues in the FeSV R and U5 regions were homologous to sequences within the same regions of the other viral long terminal repeats. Unexpectedly, alignment of the FeSV sequences with those of the Moloney murine sarcoma and simian sarcoma viruses showed similar extents of homology within U3. The homologous U3 regions included the inverted repeats, a single set of putative enhancer sequences, corresponding to a "72-base-pair" repeat, and sequences, including the CAT and TATA boxes, characteristic of eucaryotic promotors. The 5' leader sequences of both FeSV strains included a binding site for prolyl tRNA and a putative splice donor sequence. In addition, the FeSV leader contained a long open reading frame which was adjacent to and in phase with the ATG codon at the 5' end of the FeSV gag gene. The open reading frame could code for a signal peptide of about 7.4 kilodaltons. Our results support the concept that the virogenic portions of both FeSV and simian sarcoma virus were ancestrally derived from viruses of rodent origin, with conservation of regulatory sequences as well as the viral structural genes.

Base Sequence↗
PubMed1986

The terminal a sequence of the herpes simplex virus genome contains the promoter of a gene located in the repeat sequences of the L component.

The herpes simplex virus DNA genome consists of two covalently linked components, L and S. The unique sequences of the L component are flanked by 9-kilobase-pair inverted repeat sequences ab and b'a', whereas those of the S component are flanked by 6.5-kilobase-pair inverted repeat sequences c'a' and ca. We report that the 500-base-pair a sequence contains the promoter-regulatory domain and the transcription initiation site of a diploid gene, the coding sequences of which are located in the b sequences of the inverted repeats of the L component. The chimeric gene constructed by fusion of the a sequence to the coding sequences of the thymidine kinase gene and recombined into the viral genome was regulated as a gamma 1 gene. The size of the protein predicted from its sequence is 358 amino acids; it was designated as infected cell protein (ICP) 34.5. Thus, the inverted repeats flanking the unique sequences of the L component contain two genes specifying ICP0 and ICP34.5, respectively. Moreover, in addition to the cis-acting sites for the inversion of L and S components relative to each other, for cleavage of unit length DNA molecules from head-to-tail concatemers, and for packaging of the DNA into capsids, the a sequence also contains the promoter-regulatory domain and transcription initiation sites of a gene.

Amino Acid Sequence↗
PubMed1978

IS1 insertion generates duplication of a nine base pair sequence at its target site.

Three independent integrations of the E. coli insertion sequence, IS1, into the gal operon have been analyzed. DNA sequences of portions of the wild-type galT gene which act as the target sites for these insertions, as well as the corresponding gal/IS1 junctions, are reported. Two features are particularly noteworthy. First, similar sequences appearing in inverted orientation consitute the ends of IS1: 18 of the terminal 23 base pairs at each end are identical. Second, in all three insertions, a 9 base pair segment found once in the wild-type sequence at the site of insertion is duplicated and appears in the same orientation at each end of the inserted element. The sequence of this 9 base pair repeat is different for each insertion analyzed. No homology between the inverted repeat sequences at the ends of IS1 and the sequences of the target sites is observed. Models for the mechanism of IS1 insertion are proposed.

Base Sequence↗
PubMed1995

The archaeal dnaK-dnaJ gene cluster: organization and expression in the methanogen Methanosarcina mazei.

The organization and expression of the first archeael dnaK-dnaJ gene cluster cloned and sequenced have been elucidated. The work focused on the methanogen Methanosarcina mazei strain S-6, but a survey of two other strains (JC3 and LYC) and species (Methanosarcina sp. JCV and Methanosarcina acetivorans) showed that the findings are pertinent to other mesophilic methanosarcinas as well. The organization and some expression features of the archaeal genes resemble eubacterial equivalents for which comparable sequence information is available. However, the archaeal genes also display characteristics that are distinct from those of eubacterial and eucaryotic homologs. dnaK and dnaJ are transcribed into monocistronic messages. The initiation site is the same for transcription under optimal cell-growth conditions, and under stress due to a temperature upshift. The two genes are expressed constitutively at lower levels than those observed after heat shock. The constitutive and post-heat-shock expression levels are higher for dnaK than for dnaJ. Both genes withstand heat shocks of at least one and a half hours without a decline in transcript levels. While the transcription termination signals are to some extent reminiscent of those of eubacteria, the initiation signals are not. These have archaeal characteristics, which resemble those of eukaryotes. The intergenic dnaK-dnaJ region contains inverted repeats. These have the potential to build firm stem-loops in the transcript and in single-stranded DNA.

Base Sequence↗
PubMed1991

Nucleotide sequence and expression of the algE gene involved in alginate biosynthesis by Pseudomonas aeruginosa.

Alginate (Alg), a random polymer of mannuronic acid and glucuronic acid residues, is synthesized and secreted by Pseudomonas aeruginosa primarily during its infection of the lungs of cystic fibrosis patients. The molecular biology and biochemistry of the enzymatic steps leading to the production of the Alg precursor GDP-mannuronic acid have been elucidated, but the mechanism of polymer formation and export of Alg are not understood. We report the nucleotide sequence of a 2.4-kb DNA fragment containing the algE gene, previously designated alg76, encoding the AlgE protein (Mr 54,361) that is believed to be involved in these late steps of Alg biosynthesis. Expression of algE appears to occur from its own promoter. The promoter region contains several direct and inverted repeat sequences and shares structural similarity with promoters of several other alg genes from P. aeruginosa. In addition, the AlgE protein was overproduced from the tac promoter in P. aeruginosa. N-terminal amino acid sequence analysis showed that the polypeptide contains a signal peptide which is cleaved to form the mature protein during AlgE export from the cell cytoplasm.

Alginates↗
PubMed2006

Early events in the binding of the pPS10 replication protein RepA to single iteron and operator DNA sequences.

RepA protein, encoded in the Pseudomonas pPS10 replicon, is a stable dimer in solution (dRepA), acting as a self-repressor of repA transcription through binding to an inverted repeat operator. However, RepA monomers (mRepA) are required to initiate plasmid replication upon binding to four directly repeated DNA sequences (iterons). RepA is composed of two winged-helix (WH) domains: C-terminal WH2 is the main DNA-binding domain (DBD) for both target sequences, whereas N-terminal WH1 acts as dimerization interface in dRepA, but becomes a second DBD in mRepA. On the basis of CD spectroscopy, hydrodynamics, X-ray crystallography and model building studies, we proposed previously that the activation of RepA initiator implies a large structural change in WH1, coupled to protein monomerization and interdomain compaction. Here, we report novel features in the process. Binding curves of RepA to an iteron, followed by fluorescence anisotropy in solution and by surface plasmon resonance on immobilized DNA, exhibit the profiles characteristic of transitions between three states. In contrast, RepA-R93C, a monomeric activated mutant, exhibits a single binding transition. This suggests the presence of an intermediate species in the iteron-induced dissociation and structural transformation of RepA. High concentrations of bovine serum albumin or ovalbumin (macromolecular crowding) enhance RepA affinity for an iteron in solution and, in gel mobility-shift assays, result in the visualization of novel protein-DNA complexes. RepA-induced DNA bending requires the binding of two WH domains: either both WH2 in dimers (operator) or WH1 plus WH2 in monomers (iteron).

Animals↗
PubMed1984

Dictyostelium transposable element DIRS-1 preferentially inserts into DIRS-1 sequences.

Sequence analysis of genomic clones containing the intact Dictyostelium transposable element DIRS-1 reveals that in five of six cases DIRS-1 has inserted into other DIRS-1 sequences. The nucleotide sequences just beyond the endpoints of the terminal repeats of five different genomic clones can be aligned with different regions of the internal nucleotide sequence of DIRS-1. In the three genomic clones which contain flanking sequences on both sides of the element, both flanking sequences are homologous with DIRS-1. In one of these clones, both extended flanking sequences represent the full 4.1-kilobase EcoRI fragment of DIRS-1, which has been interrupted by the insertion of an intact DIRS-1 element. There is no duplication or deletion (except possibly 1 base) of the DIRS-1 sequence upon insertion of a second DIRS-1 transposon. DIRS-1-into-DIRS-1 insertions can occur in either a colinear or inverted orientation with respect to the target sequence; the target sequence need not be an intact DIRS-1 element. We also describe a cDNA clone which could be derived by transcription of a sequence that resulted from a DIRS-1-into-DIRS-1 insertion and discuss its significance concerning the function of the heat-shock promoters found in the terminal repeats of DIRS-1 and in other DIRS-1-related sequences.

Base Sequence↗
PubMed2006

Both sense and antisense strands of the LTR of the Schistosoma mansoni Pao-like retrotransposon Sinbad drive luciferase expression.

Long terminal repeat (LTR) retrotransposons, mobile genetic elements comprising substantial proportions of many eukaryotic genomes, are so named for the presence of LTRs, direct repeats about 250-600 bp in length flanking the open reading frames that encode the retrotransposon enzymes and structural proteins. LTRs include promotor functions as well as other roles in retrotransposition. LTR retrotransposons, including the Gypsy-like Boudicca and the Pao/BEL-like Sinbad elements, comprise a substantial proportion of the genome of the human blood fluke, Schistosoma mansoni. In order to deduce the capability of specific copies of Boudicca and Sinbad LTRs to function as promotors, these LTRs were investigated analytically and experimentally. Sequence analysis revealed the presence of TATA boxes, canonical polyadenylation signals, and direct inverted repeats within the LTRs of both the Boudicca and Sinbad retrotransposons. Inserted in the reporter plasmid pGL3, the LTR of Sinbad drove firefly luciferase activity in HeLa cells in its forward and inverted orientation. In contrast, the LTR of Boudicca did not drive luciferase activity in HeLa cells. The ability of the Sinbad LTR to transcribe in both its forward and inverted orientation represents one of few documented examples of bidirectional promotor function.

Animals↗
PubMed1985

Architecture and anatomy of the chromosomal locus in human chromosome 21 encoding the Cu/Zn superoxide dismutase.

The SOD-1 gene on chromosome 21 and approximately 100 kb of chromosomal DNA from the 21q22 region have been isolated and characterized. The gene which is present as a single copy per haploid genome spans 11 kb of chromosomal DNA. Heteroduplex analysis and DNA sequencing reveals five rather small exons and four introns that interrupt the coding region. The donor sequence at the first intron contains an unusual variant dinucleotide 5'-G-C, rather than the highly conserved 5'-GT. The unusual splice junction is functional in vivo since it was detected in both alleles of the SOD-1 gene, which were defined by differences in the length of restriction endonuclease fragments (RFLPs) that hybridize to the cDNA probe. Genomic blots of human DNA isolated from cells trisomic for chromosome 21 (Down's syndrome patients) show the normal pattern of bands. At the 5' end of gene there are the 'TATA' and 'CAT' promoter sequences as well as four copies of the -GGCGGG- hexanucleotide. Two of these -GC- elements are contained within a 13 nucleotide inverted repeat that could form a stem-loop structure with stability of -33 kcal. The 3'-non coding region of the gene contains five short open reading-frames starting with ATG and terminating with stop codons.

Bacteriophage lambda↗