Roles of the Escherichia coli heat shock sigma factor 32 in early and late gene expression of bacteriophage T4.

ABSTRACTSpoIIQ is an essential component of a channel connecting the developing forespore to the adjacent mother cell duringBacillus subtilissporulation. This channel is generally required for late gene expression in the forespore, including that directed by the late-acting sigma factor σG. Here, we present evidence that SpoIIQ also participates in a previously unknown gene regulatory circuit that specifically represses expression of the gene encoding the anti-sigma factor CsfB, a potent inhibitor of σG. ThecsfBgene is ordinarily transcribed in the forespore only by the early-acting sigma factor σF. However, in a mutant lacking the highly conserved SpoIIQ transmembrane amino acid Tyr-28,csfBwas also aberrantly transcribed later by σG, the very target of CsfB inhibition. This regulation ofcsfBby SpoIIQ Tyr-28 is specific, given that the expression of other σF-dependent genes was unaffected. Moreover, we identified a conserved element within thecsfBpromoter region that is both necessary and sufficient for SpoIIQ Tyr-28-mediated inhibition. These results indicate that SpoIIQ is a bifunctional protein that not only generally promotes σGactivity in the forespore as a channel component but also specifically maximizes σGactivity as part of a gene regulatory circuit that represses σG-dependent expression of its own inhibitor, CsfB. Finally, we demonstrate that SpoIIQ Tyr-28 is required for the proper localization and stability of the SpoIIE phosphatase, raising the possibility that these two multifunctional proteins cooperate to fine-tune developmental gene expression in the forespore at late times.IMPORTANCECellular development is orchestrated by gene regulatory networks that activate or repress developmental genes at the right time and place. Late gene expression in the developingBacillus subtilisspore is directed by the alternative sigma factor σG. The activity of σGrequires a channel apparatus through which the adjacent mother cell provides substrates that generally support gene expression. Here we report that the channel protein SpoIIQ also specifically maximizes σGactivity as part of a previously unknown regulatory circuit that prevents σGfrom activating transcription of the gene encoding its own inhibitor, the anti-sigma factor CsfB. The discovery of this regulatory circuit significantly expands our understanding of the gene regulatory network controlling late gene expression in the developingB. subtilisspore.

Download Full-text

A new gene of Escherichia coli K-12 whose product participates in T4 bacteriophage late gene expression: interaction of lit with the T4-induced polynucleotide 5'-kinase 3'-phosphatase.

Journal of Bacteriology ◽

10.1128/jb.140.1.83-91.1979 ◽

1979 ◽

Vol 140 (1) ◽

pp. 83-91 ◽

Cited By ~ 10

Author(s):

W Cooley ◽

K Sirotkin ◽

R Green ◽

L Synder

Keyword(s):

Gene Expression ◽

Escherichia Coli ◽

Late Gene ◽

Late Gene Expression ◽

T4 Bacteriophage ◽

New Gene ◽

K 12

Download Full-text

Bacteriophage T4 late gene expression: Overlapping promoters direct divergent transcription of the base plate gene cluster

Virology ◽

10.1016/0042-6822(89)90617-x ◽

1989 ◽

Vol 171 (2) ◽

pp. 475-483 ◽

Cited By ~ 11

Author(s):

Vincezo Scarlato ◽

Aurora Storlazzi ◽

Silvana Gargano ◽

Antonino Cascino

Keyword(s):

Gene Expression ◽

Gene Cluster ◽

Bacteriophage T4 ◽

Base Plate ◽

Late Gene ◽

Late Gene Expression ◽

Divergent Transcription

Download Full-text

Membrane Topology of the Bacillus subtilis Pro-ςK Processing Complex

Journal of Bacteriology ◽

10.1128/jb.182.2.278-285.2000 ◽

2000 ◽

Vol 182 (2) ◽

pp. 278-285 ◽

Cited By ~ 45

Author(s):

David H. Green ◽

Simon M. Cutting

Keyword(s):

Gene Expression ◽

Escherichia Coli ◽

Conformational Change ◽

Transmembrane Domain ◽

Integral Membrane Proteins ◽

Membrane Topology ◽

Late Gene ◽

Late Gene Expression ◽

Processing Protease ◽

Positive Effect

ABSTRACT Activation of the final sporulation-specific transcription factor, ςK, is regulated by a signal emanating from the forespore which interacts with the pro-ςK processing complex, comprising SpoIVFA, BofA, and the pro-ςK processing protease, SpoIVFB. Mature ςK then directs late gene expression in the parental compartment of the developing sporangial cell. The nature of this complex and how it is activated to process pro-ςK are not understood. All three proteins are predicted to be integral membrane proteins. Here, we have analyzed the membrane topology of SpoIVFA and SpoIVFB by constructing chimeric forms of spoIVFA and spoIVFB with the complementary reporters phoA and lacZ and analyzing activity in Escherichia coli. SpoIVFA was found to have a single transmembrane-spanning domain, while SpoIVFB was shown to have six transmembrane-spanning domains (6-transmembrane configuration). Further, SpoIVFA is required to stabilize SpoIVFB in the membrane. SpoIVFB was shown to have a 4-transmembrane configuration when expressed on its own but was found to have a 6-transmembrane configuration when coexpressed with SpoIVFA, while BofA had a positive effect on the assembly of both SpoIVFA and SpoIVFB. The single transmembrane domain of SpoIVFA (approximately residues 73 to 90) was shown to be the principle determinant in stabilizing the 6-transmembrane configuration of SpoIVFB. Although thebofB8 allele, which uncouples the ςKcheckpoint, did not appear to promote a conformational change from a 6- to 4-transmembrane configuration of SpoIVFB (apparently ruling out a profound conformational change as the mechanism of activating SpoIVFB proteolytic activity), instability of SpoIVFB may be an important factor in SpoIVFB-mediated processing of pro-ςK.

Download Full-text

Competence for Genetic Transformation in Streptococcus pneumoniae: Mutations in σABypass the ComW Requirement for Late Gene Expression

Journal of Bacteriology ◽

10.1128/jb.00354-16 ◽

2016 ◽

Vol 198 (17) ◽

pp. 2370-2378 ◽

Cited By ~ 9

Author(s):

Yanina Tovpeko ◽

Junqin Bai ◽

Donald A. Morrison

Keyword(s):

Gene Expression ◽

Streptococcus Pneumoniae ◽

Genetic Transformation ◽

Sigma Factor ◽

Specific Protein ◽

Late Gene ◽

Late Gene Expression ◽

Content Type ◽

Σ Factor

ABSTRACTStreptococcus pneumoniaeis able to integrate exogenous DNA into its genome by natural genetic transformation. Transient accumulation of high levels of the onlyS. pneumoniaealternative σ factor is insufficient for development of full competence without expression of a second competence-specific protein, ComW. The ΔcomWmutant is 104-fold deficient in the yield of recombinants, 10-fold deficient in the amount of σXactivity, and 10-fold deficient in the amount of σXprotein. The critical role of ComW during transformation can be partially obviated by σAmutations clustered on surfaces controlling affinity for core RNA polymerase (RNAP). While strains harboring σAmutations in thecomWmutant background were transforming at higher rates, the mechanism of transformation restoration was not clear. To investigate the mechanism of transformation restoration, we measured late gene expression in σA* suppressor strains. Restoration of late gene expression was observed in ΔcomWσA* mutants, indicating that a consequence of the σA* mutations is, at least, to restore σXactivity. Competence kinetics were normal in ΔcomWσA* strains, indicating that strains with restored competence exhibit the same pattern of transience as wild-type (WT) strains. We also identified a direct interaction between ComW and σXusing the yeast two-hybrid (Y2H) assay. Taken together, these data are consistent with the idea that ComW increases σXaccess to core RNAP, pointing to a direct role of ComW in σ factor exchange during genetic transformation. However, the lack of late gene shutoff in ΔcomWmutants also points to a potential new role for ComW in competence shutoff.IMPORTANCEThe sole alternative sigma factor of the streptococci, SigX, regulates development of competence for genetic transformation, a widespread mechanism of adaptation by horizontal gene transfer in this genus. The transient appearance of this sigma factor is strictly controlled at the levels of transcription and stability. This report shows that it is also controlled at the point of its substitution for SigA by a second transient competence-specific protein, ComW.

Download Full-text