Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

SDS-polyacrylamide gel analysis of P22-infected Salmonella has allowed identification of the c2 repressor (MW 31,000) and study of repressor synthesis in regulatory mutants of P22. Repressor is synthesized in reduced amounts or is absent in infections with P22, clNo.7, P22, c2 am08, P22 c3 am03, and P22 c3 am012, but is synthesized in markedly increased amounts in the virulent mutant, P22 virB3, and its component mutants, vx and k5. Higher levels of repressor are also found in the P22 cly 17 mutant.
Mol Gen Genet 1979 Jan 02
PMID:Repressor synthesis in regulatory mutants of bacteriophage P22. 36 97

The ant products of Salmonella phage P22, synthesized by its immI region, releases when acting in cis replication inhibition for phages P22 and L. When ant product acts trans on a coinfecting immunity sensitive phage (Thomas-Bertani-experiment as test for release of replication inhibition) full replication ensues only if both superinfecting phages are homologous in the specificities of their immC and immI regions. If these regions are heterologous, differing in immC, immI or in both, the replication of the phage expected to be complemented by ant is inhibited. This inhibition is observed in both L- and Px-lysogenic bacteria and can be released in case of ant- amber phage by action of ant in cis in su+ lysogenic bacteria.
Mol Gen Genet 1979 Jan 11
PMID:Cis- and trans-activity of P22 antirepressor protein against c-repression specified by the closely related Salmonella phages L and Px1. 37 92

TB37 is a dna A-mutant of Salmonella typhimurium in which the initiation of DNA replication at the origin is stopped at 42 degrees C. DNA synthesis in uninfected cells of this strain and in cells infected by phage P22 was followed by the pulse labelling technique. DNA replication ceases completely after about 50 minutes at the high temperature. After lytic infection with P22 (c2) at this time, DNA synthesis starts immediately and increases at a rate well comparable to the permissive control. Obviously the temperature sensitive function of the dnaA-product is dispensable for P22 DNA replication, especially for its initiation. This result is confirmed by the normal yield of phage particles under these conditions, provided that a late step in P22 maturation which naturally is temperature sensitive can proceed at low temperature. If TB37 is infected at 42 degrees C with P22 wild type, an unexpected high rate of phage controlled DNA synthesis is observed. Preliminary results seem to indicate that the process of integration is a prerequisite for part of this synthesis.
Mol Gen Genet 1979 Mar 27
PMID:Replication and maturation of phage P22 in a mutant of Salmonella typhimurium temperature sensitive in initiation of DNA replication. 37 15

We have designed a new medium for the differentiation of mutants of Salmonella typhimurium defective in the ability to reduce nitrate with formate, and have characterized 24 formate dehydrogenase (FDH) mutants isolated on this medium. The mutants were assayed for the ability to use formate to reduce benzyl viologen and phenazine methosulfate, and were mapped by means of conjugation and P22-mediated transduction. Mutants lacking the ability to reduce either dye were found to map at three distinct sites: at a site co-transducible with xyl (presumably fdhA), at a site or sites between 13U and 33U, but not co-transducible with aroA, bio, purB, pyrC, or pyrD (near, but not identical with fdhB), and at asite 10-20% co-transducible with pyrE, for which we suggest the designation fdhC. Six mutant isolates reduced benzyl viologen, but not phenazine methosulfate. They retained the ability to produce nitrite during growth with nitrate. They mapped between 83U and 89U, but no co-transduction was found with metE, glnA, metB, or argH. The combined biochemical and genetic data suggest the existence of a gene in this area which is essential for the reduction of nitrate with formate, but not for formate hydrogenlyase activity or for nitrate reductase activity.
Mol Gen Genet 1979
PMID:Formate dehydrogenase mutants of Salmonella typhimurium: a new medium for their isolation and new mutant classes. 39 18

The virulent mutants P22 virB vy and P22 vy mutants, both insensitive to mnt-repressor, transactivate the early genes of a P22 prophage. The transactivation of early P22 prophage genes depends strictly on the expression of gene ant ("antirepressor"-protein) by the superinfecting P22 mutant and therefore occurs by derepression.
Mol Gen Genet 1978 Sep 08
PMID:Ant-mediated transactivation of early genes in Salmonella prophage P22 by superinfecting virulent P22 mutants. 71 19

Phage P22 mutation c27 defines a site required for establishment , but not maintenance of repressor synthesis. This study confirms that P22 c27 is able to synthesize repressor if active repressor is present. An interaction involving gene products of c1 and c3 and the site c27 retards expression of the lytic genes of P22. Mutations in gene c1 eliminate the retardation of lytic gene expression, but c27 does not alleviate the retardation. These results are used to construct a model that postulates that binding of c1 and c3 products to DNA at or near c27 is sufficient to cause retardation of lytic gene expression. The functioning of c27 is contrasted to that of the analogous cy mutants of lambda. The effect of the c27 mutation upon alleviation of "cl repression" was studied in a partial revertant of Salmonella typhimurium Pox-1 in which c1 repression is exaggerated. The higher frequency of lysogenization seen in the mutant host is related to enhanced cl repression.
Mol Gen Genet 1976 Mar 22
PMID:Site c27 in phage P22 and control of the pathway to lysogeny. 77 92

Coliphage BF23 develops in Salmonella typhimurium rough strains. The phage is neither restricted nor modified by S. typhimurium. The growth patterns of the phage were slightly different in S. typhimurium than in Escherichia coli, although phage propagated on S. typhimurium is identical to the phage propagated in E. coli by several criteria used. Mutants of S. typhimurium resistant to BF23 were isolated and found to map (by P22- and Pl-mediated transduction) in the same position as bfe mutants of E. coli. The order of genes was: metB - argC - bfe - rif - purD - metA. Phage BF23 does not form plaques on smooth S. typhimurium strains, since the phage fails to adsorb irreversibly to smooth cells. Nevertheless, on solid agar, the phage prevents growth of many (but not all) smooth strains. Moreover, UV- and alkali-inactivated phage BF23, although unable to form plaques on sensitive hosts, retains the ability to prevent growth of the host on solid medium. This ability is sensitive to protease and resistant to DNAse and RNase. Heat treatment of the phage causes rapid loss of the cell-growth-preventing-ability whereas the ability to form plaques is lost much more slowly. These results lead to a proposal that phage BF23 virions carry a colicin-like factor that kills sensitive cells.
Mol Gen Genet 1976 Aug 19
PMID:Growth of coliphage BF23 on rough strains of Salmonella typhimurium: the bfe locus. 78 57

Phage DNA was accumulated in cells of E. coli B, infected with the phage T4DtsLB3 (gene 42), without the synthesis of late proteins (in the presence of chloramphenicol). Then (stage II), chloramphenicol was removed and further replication of the phage DNA suppressed with hydroxyurea and by simultaneously raising the temperature to 40 degrees. The media M9 or M9 with 1% amino acid were used; the times of addition of chloramphenicol and the hydroxyurea concentration were also varied. It was also shown that in medium M9, at stage II, chiefly early proteins were synthesized. In the medium containing amino acids, at stage II the following was observed: 1) DNA synthesis was entirely suppressed and a degradation of DNA occurred; 2) both early and late proteins were synthesized, with a predominance of the latter; 3) an assembly of the elements of the phage tails and capsids occurred without the neck and flagellum, and a small number of phage particles were also found; 4) the capsids, isolated in a sucrose density gradient after lysis with chloroform, contained the proteins Palt, P20, P23, P24, several unidentified proteins, and did not contain Pwac, P23, and P22, 5) the yield of viable phage varied from 0.05 to 15% per cell. Thus, the entire morphogenesis of T4 phage can occur without accompanying replication of phage DNA.
Mol Biol (Mosk)
PMID:DNA replication and head assembly in bacteriophage T4. 102 49

Mutation of the gene m3 of phage P22 causes permanent depression of macromolecular synthesis in the infected host and thus inhibits phage development as indicated by burst size and lysozyme production. The permanent depression of macromolecular synthesis is most probably due to blockage of the transport process. The m3 allele is dominant over m+. m3 allows some transcription of phage genes (however, the difference between early and late function is not clear). The inhibitory effect of m3 on DNA synthesis may be indirect.
Mol Gen Genet 1975
PMID:Effect of m3 gene on the development of phage P22. 110 21

Mutants of P22 which have been located in the c2 repressor gene were examined. The most rightward "c2 mutation" was found to define a site that is necessary only for the establishment and not for the maintenance of repressor synthesis. We conclude that this site c27 is an analog of cy mutants in phage lambda which define a promotor for repression establishment (pre). The K5 mutation of P22 maps between c27 and all other c2 mutants. Examination of its biological behavior and direct measurement of repressor activity show that K5 does not affect c2 repression. A model to explain these findings implies that c27 and K5 affect transcripts of opposite directions. P22 c1 mutants do not allow c2 repressor synthesis and we conclude that the activity of c1 product (and presumably c3 product) at the site defined by c27 is necessary for repressor synthesis. The combined activity of c1 and c3 product at c27 is postulated to promote repressor synthesis and block transcription of vegatative phage genes to the right of K5. After repressor synthesis has been established, another site analogous to lambda prm is sufficient for repressor synthesis and c27 is no longer required. These observations and conclusions point to a very close analogy between repressor synthesis and control in phages P22 and lambda.
Mol Gen Genet 1975
PMID:Further structural and functional analogies between the repressor regions of phages P22 and lambda. 110 26


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