Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “SPP1”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
PubMed2004

Bacillus subtilis operon encoding a membrane receptor for bacteriophage SPP1.

The results reported here have identified yueB as the essential gene involved in irreversible binding of bacteriophage SPP1 to Bacillus subtilis. First, a deletion in an SPP1-resistant (pha-2) strain, covering most of the yueB gene, could be complemented by a xylose-inducible copy of yueB inserted at amyE. Second, disruption of yueB by insertion of a pMutin4 derivative resulted in a phage resistance phenotype regardless of the presence or absence of IPTG (isopropyl-beta-D-thiogalactopyranoside). YueB homologues are widely distributed in gram-positive bacteria. The protein Pip, which also serves as a phage receptor in Lactococcus lactis, belongs to the same family. yueB encodes a membrane protein of approximately 120 kDa, detected in immunoblots together with smaller forms that may be processed products arising from cleavage of its long extracellular domain. Insertional inactivation of yueB and the surrounding genes indicated that yueB is part of an operon which includes at least the upstream genes yukE, yukD, yukC, and yukBA. Disruption of each of the genes in the operon allowed efficient irreversible adsorption, provided that yueB expression was retained. Under these conditions, however, smaller plaques were produced, a phenotype which was particularly noticeable in yukE mutant strains. Interestingly, such reduction in plaque size was not correlated with a decreased adsorption rate. Overall, these results provide the first demonstration of a membrane-bound protein acting as a phage receptor in B. subtilis and suggest an additional involvement of the yukE operon in a step subsequent to irreversible adsorption.

Amino Acid Sequence↗
PubMed1982

SPP1-mediated plasmid transduction.

The virulent Bacillus subtilis phage SPP1 transduces plasmid DNA. Plasmid-transducing phages contain only plasmid DNA. Such DNA represents a concatemer of monomeric plasmid molecules with the molecular weight of mature SPP1 DNA. Biological parameters of plasmid transduction are described.

Bacillus subtilis↗
PubMed2002

An osteopontin (SPP1) polymorphism is associated with systemic lupus erythematosus.

Osteopontin (SPP1) is a soluble ligand with pleomorphic immunologic activities including activation of macrophage chemotaxis, promotion of Th1 responses, and activation of B1 B cells. It has been implicated in the development of murine lupus and is overexpressed in humans with systemic lupus erythematosus (SLE). We examined a polymorphism of osteopontin for an association with lupus in humans in an effort to determine whether there is any evidence that a genetic predisposition to altered osteopontin expression might explain the overexpression seen in human SLE patients. A silent polymorphism (707C>T, rs1126616) of osteopontin was significantly associated with SLE. Additional associations with renal disease and opportunisitic infections were suggested. This is the first phenotypic association with a polymorphic variant of osteopontin.

Chi-Square Distribution↗
PubMed1986

Requirements for the formation of plasmid-transducing particles of Bacillus subtilis bacteriophage SPP1.

We had previously proposed that the production of concatemeric plasmid DNA in plasmid-transducing SPP1 particles is a consequence of phage-directed rolling-circle-type replication of plasmid DNA. The production of such DNA was greatly enhanced when DNA/DNA homology was provided between phage and plasmid DNAs (facilitation of transduction). Here we present evidence that synthesis of concatemeric plasmid DNA can proceed after phage infection under conditions non-permissive for plasmid replication. We also propose that the naturally occurring homology between plasmid and phage is sufficient to account for the frequency of transduction observed in the absence of facilitating homology. Homology of greater than 47 bp gives the maximal facilitation of plasmid transduction. Recombination is not an essential part in the synthesis of concatemeric plasmid DNA.

Bacillus subtilis↗
PubMed1995

The small subunit of the terminase enzyme of Bacillus subtilis bacteriophage SPP1 forms a specialized nucleoprotein complex with the packaging initiation region.

Initiation of SPP1 DNA packaging requires the gene 1 and gene 2 products (G1P and G2P), which are different subunits of the terminase enzyme. G1P specifically recognizes the phage packaging initiation region (pac). The apparent equilibrium constant for the G1P-pac-DNA complex was estimated to be 9 nM. DNase I footprinting experiments reveal that the pac region can be subdivided into three discrete sites (pacL, pacC and pacR). G1P binds co-operatively to the non-adjacent pacL and pacR sites. Several G1P protomers bind to the target sequences which map close to the pac cleavage site (pacC site), but do not overlap with it. G1P interacts in a different fashion with the encapsidated (pacR site) and with the non-encapsidated (pacL site) end of the phage genome. G1P interaction with the intrinsically bent pacL DNA occurs only on one face of the DNA double helix. G1P binding to the pacL and in the pacR region results in a DNA loop. Electron microscopy of purified G1P shows that the protein is an oligomer in solution. G1P binding to the core region of the pacL site could facilitate the formation of a higher-order nucleoprotein structure. This specialized complex would allow the pac DNA to form a loop between binding sites brought together by interaction with G1P. The results presented here suggest that G1P could provide a tool to discriminate the first encapsidated end, which contains pacR, from the non-encapsidated pacL end.

Bacillus Phages↗
PubMed1975

Transfection with heteroduplex SPP1 DNA: a pyrimidine dimer induced influence on the conversion pattern.

Bacillus subtilis competent cells were transfected with SPP1 heteroduplices having pyrimidine dimers in one of the strands. The data obtained reveal that excision repair of the pyrimidine dimers influences the ratio of wild type versus mutant progeny observed in "normal" heteroduplex transfection. With increased exposure of one strand to UV dose the percentage of infective centers having the unirradiated strand genotype shows an increase. A comparison of the transfection data in her+ and her- host excludes asymmetric replication as the cause of the observed changes in the conversion pattern. The data can be explained on the basis of a dimer induced co-excision of the mismatched region. In addition transfection data from wild type/deletion mutant heteroduplices where the strand of mutant origin was irradiated exclude the possibility of the wild type loop being excised during uptake.

Bacillus subtilis↗
PubMed1981

Promoter sites in the genome of B. subtilis phage SPP1.

Transcriptional complexes formed in vitro using DNA of B. subtilis phage SPP1 as template and E. coli and B. subtilis RNA polymerases were analyzed by electron microscopy. Both enzymes recognize the same five strong promoters in the early region of the genome. Strand selection at these sites was identical with both enzymes. These results correlate well with data obtained from in vivo transcription studies. Transcriptional activity in the late region of the genome was very low, not permitting the identification of promoter sites.

Bacillus subtilis↗
PubMed2005

Bacillus subtilis bacteriophage SPP1-encoded gene 34.1 product is a recombination-dependent DNA replication protein.

SPP1-encoded replication and recombination proteins, involved in the early steps of the initiation of concatemeric DNA synthesis, have been analyzed. Dimeric G34.1P exonuclease degrades, with a 5' to 3' polarity and in a Mg2+-dependent reaction, preferentially linear double-stranded (ds) DNA rather than single-stranded (ss) DNA. Binding of the replisome organizer, G38P, to its cognate sites (oriDNA) halts the 5' to 3' exonucleolytic activity of G34.1P on dsDNA. The G35P recombinase increases the affinity of G34.1P for dsDNA, and stimulates G34.1P activity on dsDNA, but not on ssDNA. Then, filamented G35P promotes limited strand exchange with a homologous sequence. The ssDNA binding protein, G36P, protects ssDNA from the G34.1P exonuclease activity and stimulates G35P-catalyzed strand exchange. The data presented suggest a model for the role of G34.1P during initiation of sigma replication: G38P bound to oriDNA might halt replication fork progression, and G35P, G34.1P and G36P in concert might lead to the re-establishment of a unidirectional recombination-dependent replication that accounts for the direction of DNA packaging.

Adenosine Triphosphate↗
PubMed2005

Bacillus subtilis bacteriophage SPP1 G40P helicase lacking the n-terminal domain unwinds DNA bidirectionally.

Bacillus subtilis bacteriophage SPP1 G40P hexameric replicative DNA helicase unidirectionally translocates with a 5'-->3' polarity while separating the DNA strands. A G40P mutant derivative lacking the N-terminal domain (containing amino acid residues 110-442 from G40P, G40PDeltaN109) was purified and characterized. G40PDeltaN109 showed an ATPase activity that was dependent on the presence of single-stranded (ss) DNA. Unlike G40P, G40PDeltaN109 was shown to bind with similar affinity both ssDNA arms of forked structures by nuclease protection assays. In a pH-dependent manner, G40PDeltaN109 unwound a branched double-arm substrate preferentially with a 3'-->5' polarity. Our results show that the linker region and the C-terminal domain of G40P are sufficient to render an enzyme capable of encircling the ssDNA tails of the forked DNA and to unwind DNA with both 5'-->3' and 3'-->5' polarity. The presence of the N-terminal domain, which does not play an essential role in helicase action, might be required indirectly for strand discrimination and polarity of translocation.

Adenosine Triphosphate↗
PubMed2004

The portal protein plays essential roles at different steps of the SPP1 DNA packaging process.

A large number of viruses use a specialized portal for entry of DNA to the viral capsid and for its polarized exit at the beginning of infection. These families of viruses assemble an icosahedral procapsid containing a portal protein oligomer in one of its 12 vertices. The viral ATPase (terminase) interacts with the portal vertex to form a powerful molecular motor that translocates DNA to the procapsid interior against a steep concentration gradient. The portal protein is an essential component of this DNA packaging machine. Characterization of single amino acid substitutions in the portal protein gp6 of bacteriophage SPP1 that block DNA packaging identified sequential steps in the packaging mechanism that require its action. Gp6 is essential at early steps of DNA packaging and for DNA translocation to the capsid interior, it affects the efficiency of DNA packaging, it is a central component of the headful sensor that determines the size of the packaged DNA molecule, and is essential for closure of the portal pore by the head completion proteins to prevent exit of the DNA encapsidated. Functional regions of gp6 necessary at each step are identified within its primary structure. The similarity between the architecture of portal oligomers and between the DNA packaging strategies of viruses using portals strongly suggests that the portal protein plays the same roles in a large number of viruses.

Amino Acid Substitution↗
PubMed1998

Bacillus subtilis DnaG primase stabilises the bacteriophage SPP1 G40P helicase-ssDNA complex.

Purified Bacillus subtilis DnaG primase (predicted molecular mass 68.8 kDa) behaves as a monomer in solution. We demonstrate that DnaG physically interacts with bacteriophage SPP1 hexameric helicase G40P (G40P6) in the absence of ATP. G40P6-ATP forms an unstable complex with ssDNA, and by itself carries out ATP-driven translocation along a ssDNA template with low processivity. The presence of DnaG in the reaction mixture increased the helicase activity of G40P6 about 3-fold, but not the ATPase activity. The results presented here suggest that the DnaG protein stabilises the G40P6-ssDNA complexes.

Adenosine Triphosphatases↗
PubMed1997

Bacillus subtilis bacteriophage SPP1 terminase has a dual activity: it is required for the packaging initiation and represses its own synthesis.

The B. subtilis bacteriophage SPP1 terminase, encoded by genes 1 and 2, is required for the initiation of headful packaging. The DNA segment to which gene 1 product (G/P) binds includes the pacL and pacR sites and the late PL1 and PL2 promoters from which genes 1 to 7 are transcribed. When SPP1wt or SPP1sus115 (gene 6-) phages were used to infect a B. subtilis sup0 strain, the gene 1 to 7 mRNA synthesis was reduced at late times of infection. This was not observed, however, when either chloramphenicol was added 7 min after infection with SPP1wt or when SPP1sus114 (gene 1-) or SPP1sus19 (gene 2-) were used to infect B. subtilis sup0 cells. These results suggest that the terminase enzyme functions as a repressor of its own transcription. G/P and B. subtilis RNA polymerase (RP) bind to the pacL segment, which contains the PL1 and PL2 promoter region. The binding of G/P to the pacL site does not seem to exclude RP from the promoters, despite of the overlapping of their binding sites. It is likely that the terminase protein does not repress transcription by a mere steric hindrance of RP binding.

Bacillus Phages↗
PubMed1999

Structure of the 13-fold symmetric portal protein of bacteriophage SPP1.

We have determined the three-dimensional structure of bacteriophage SPP1 portal protein (gp6) using electron microscopy at liquid-helium temperatures and angular reconstitution. The 13-fold symmetric gp6 oligomer is a turbine-shaped structure with three distinct regions: a conical stem with a central channel; the turbine wings region; and a fringe of small 'tentacles' at the end of the channel exposed to the viral head interior. The tentacle region appears flexible and may be associated with a particular function - sensing when the correct amount of DNA has been packaged. The three-dimensional structure of the gp6 SizA mutant, which packages a smaller chromosome, reveals significant differences in that region.

Bacillus Phages↗
PubMed2004

The high-resolution functional map of bacteriophage SPP1 portal protein.

An essential component in the assembly of nucleocapsids of tailed bacteriophages and of herpes viruses is the portal protein that is located at the unique vertex of the icosahedral capsid through which DNA movements occur. A library of mutations in the bacteriophage SPP1 portal protein (gp6) was generated by random mutagenesis of gene 6. Screening of the library allowed identification of 67 single amino acid substitutions that impair portal protein function. Most of the mutations cluster within stretches of a few amino acids in the gp6 carboxyl-terminus. The mutations were divided into five classes according to the step of virus assembly that they impair: (1) production of stable gp6; (2) interaction of gp6 with the minor capsid protein gp7; (3) incorporation of gp6 in the procapsid structure; (4) DNA packaging; and (5) sizing of the packaged DNA molecule. Most of the mutations fell in classes 3 and 4. This is the first high-resolution functional map of a portal protein, in which its function at different steps of viral assembly can be directly correlated with specific regions of its sequence. The work provides a framework for the understanding of central processes in the assembly of viruses that use specialized portals to govern entry and exit of DNA from the viral capsid.

Amino Acid Substitution↗
PubMed1999

Effect of the ionic environment on the molecular structure of bacteriophage SPP1 portal protein.

Bacteriophage SPP1 portal protein is a large cyclical homo-oligomer composed of 13 subunits. The solution structure and assembly behavior of this protein with high-point rotational symmetry was characterized. The purified protein was present as a monodisperse population of 13-mers, named gp6H, at univalent salt concentrations in the hundred millimolar range (>/= 250 mM NaCl) or in the presence of bivalent cations in the millimolar range (>/= 5 mM MgCl2). Gp6H had a slightly higher sedimentation coefficient, a smaller shape-dependent frictional ratio, and a higher rate of intersubunit cross-linking in the presence of magnesium than in its absence. In the absence of bivalent cations and at univalent salt concentrations below 250 mM, the 13-mer molecules dissociated partially into stable monomers, named gp6L. The monomer had a somewhat different shape from the subunit present in the 13-mer, but maintained a defined tertiary structure. The association-dissociation equilibrium was mainly between the monomer and the 13-mer with a minor population of intermediate oligomers. Their interconversion was strongly influenced by the ionic environment. Under physiological conditions, the concentration of Mg2+ found in the Bacillus subtilis cytoplasm (10-50 mM) probably promotes complete association of gp6 into 13-mer rings with a compact conformation.

Bacillus Phages↗
PubMed2003

Bacillus subtilis bacteriophage SPP1 DNA packaging motor requires terminase and portal proteins.

Initiation of headful packaging of SPP1 DNA concatemers involves the interaction of the terminase, G1P and G2P, and the portal protein, G6P. G1P, which specifically recognizes the non-adjacent pacL and pacR subsites and directs loading of G2P to pacC, interacts with G6P. G2P, which has endonuclease, DNA binding, and ATPase activities, interacts with G1P and does it transiently with G6P. The stoichiometry of G1P on the G1P.G2P complex promotes the transition from a G2P endonuclease to an ATPase. G6P does not alter the endonuclease activity of G2P. Both G1P and G6P, which do not have endogenous ATPase activity, synergistically enhance and modulate the ATPase activity of G2P. Based on these results, we propose a model in which the modulation of the ATPase and endonuclease activities of G2P accounts for the role of the terminase in headful packaging.

Bacillus subtilis↗
PubMed2006

The ectodomain of the viral receptor YueB forms a fiber that triggers ejection of bacteriophage SPP1 DNA.

The irreversible binding of bacteriophages to their receptor(s) in the host cell surface triggers release of the naked genome from the virion followed by transit of viral DNA to the host cell cytoplasm. We have purified, for the first time, a receptor from a Gram-positive bacterium that is active to trigger viral DNA ejection in vitro. This extracellular region ("ectodomain") of the Bacillus subtilis protein YueB (YueB780) was a 7 S elongated dimer forming a 36.5-nm-long fiber. YueB780 bound to the tail tip of bacteriophage SPP1. Although a stable receptor-phage interaction occurred between 0 and 37 degrees C, complete blocking of phage DNA release or partial ejection events were observed at temperatures below 15 degrees C. We also showed that the receptor was exposed to the B. subtilis surface. YueB differed structurally from phage receptors from Gram-negative bacteria. Its properties revealed a fiber spanning the full length of the 30-nm-thick peptidoglycan layer. The fiber is predicted to be anchored in the cell membrane through transmembrane segments. These features, highly suitable for a virus receptor in Gram-positive bacteria, are very likely shared by a large number of phage receptors.

Bacillus Phages↗
PubMed1990

The generation of concatemeric plasmid DNA in Bacillus subtilis as a consequence of bacteriophage SPP1 infection.

Bacteriophage SPP1 infection of Bacillus subtilis cells bearing plasmids induces the synthesis of multigenome-length plasmid molecules. Two independent pathways can account for this synthesis. In one of those, homology to the phage genome is required, whereas in the other such homology is not a prerequisite. In wild type cells both modes overlap. In dnaB(Ts), at non permissive temperature, or in recE polA strains the main concatemeric plasmid replication mode is the homology-dependent plasmid (hdp) mode. The rate of recombination-dependent concatemeric plasmid DNA synthesis is a consequence of a phage-plasmid interaction which leads to chimeric phage::plasmid DNA. The second mode, which is an homology-independent plasmid (hip) mode seems to be triggered upon the synthesis of a phage encoded product(s) (e.g. inactivation of the exonuclease V enzyme).

Bacillus subtilis↗