Bacteriophage lambda Hin function

Court, Donald L.; B, de Crombrugghe; Gottesman, M.

doi:10.1016/0022-2836(80)90062-5

Cited by 11 publications

(2 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Aliquots (20 ml) were transferred 3 and 6 min later to tubes containing ice and azide. The procedure for extraction of the RNA has been described (35 2). Four-factor genetic crosses with these mutants showed that their mutations lie in the 250-bp region to the left ofatt and have the genetic order sib3-sib2-sibl-att (unpublished data).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Posttranscriptional control of bacteriophage lambda gene expression from a site distal to the gene.

Guarneros¹,

Montañéz²,

Hernández³

et al. 1982

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The bacteriophage A int gene product, integrase, recombines the phage DNA with the host DNA at specific sites on each to accomplish lysogeny. The int gene is transcribed from two promoters, PL and PI, each regulated positively by A proteins. The expression of integrase is also controlled from a site, sib, in the b region of the phage genome. This is a unique regulatory site because it is located distal to the structural gene in relation to the promoters. The expression ofint from the PL promoter is inhibited when sib is present. This effect appears to be specific for PL because sib does not cause inhibition of PI-dependent int synthesis.A mutants that contain alterations in the site have been isolated. Sequence analyses of the mutations reveal single base changes, spanning 37 base pairs (bp) in the b region, some 240-bp beyond the int gene. Another mutant, hef13, which has a phenotype similar to that of sib, introduces a nucleotide change within the same 37-bp region. The sib and hefmutatsons cluster within a region of dyad symmetry. Regulation of int synthesis by sib occurs after transcription.of the int gene. There is no difference in the rate of .PL'promoted int mRNA synthesis in either sib' or sib-phage infections, yet int mRNA is less stable in the sib' infection. Because RNase 111 host mutants are defective in sib regulation, processing of the PL mRNA at sib by this endoribonuclease may cause int mRNA decay and decrease int synthesis.Bacteriophage A inserts its DNA into the Escherichia coli chromosome as part of the process leading to lysogeny. This integration event uses A int protein and occurs by reciprocal recombination at specific locations, named "attachment sites," in the phage (attP) and in the bacterial (attB) DNAs. The reversal of the integrative reaction is excision; this process occurs after prophage induction and allows the integrated DNA to dissociate from the bacterial chromosome. The two phage proteins int and xis are required for excisive recombination. Host factors are also required for both integration and excision, but the direction of the reaction depends primarily upon the presence of int or int and xis in the cell (1-3).Two promoters, PI and PL, control transcription of the 1.5-kilobase int-xis region (4, 5) (Fig. 1). Both promoters are positively regulated by different effectors. Gene N product allows elongation of the PL transcript through several genes into the int-xis region (11,12). The cII product is required to initiate transcription from PI by facilitating initiation by RNA polymerase (7). The PI promoter overlaps with the xis gene, and its transcript does not include all of xis (8-10). Thus a differential expression of the integration and excision systems is assured by turning on and off PI or PL Infections with cII-phage result in decreased int protein levels and integration activity (13)(14)(15). This result is unexpected because transcription initiated by RNA polymerase at PL was thought to extend through thexis-int region (11, 16). However, infection with b2cII-...

show abstract

Section: Methodsmentioning

confidence: 99%

“…Cells were concentrated to 10% of the initial volume in 10 mM MgSO4 and infected with phage at an average multiplicity of 5. After adsorption at 00C, the bacteria were resuspended in the initial volume of supplemented medium A at 390C (35).…”

Section: Methodsmentioning

confidence: 99%