Tags

Type your tag names separated by a space and hit enter

Flk couples flgM translation to flagellar ring assembly in Salmonella typhimurium.
J Bacteriol. 1998 Oct; 180(20):5384-97.JB

Abstract

The hook-basal body (HBB) is a key intermediate structure in the flagellar assembly pathway in Salmonella typhimurium. The FlgM protein inhibits the flagellum-specific transcription factor sigma28 in the absence of the intact HBB structure and is secreted out of the cell following HBB completion. The flk gene encodes a positive regulator of the activity of FlgM at an assembly step just prior to HBB completion: at the point of assembly of the P- and L-rings. FlgM inhibition of sigma28-dependent class 3 flagellar gene transcription was relieved in P- and L-ring assembly mutants (flgA, flgH, and flgI) by introduction of a null mutation in the flk gene (J. E. Karlinsey et al., J. Bacteriol. 179:2389-2400, 1997). In P- and L-ring mutant strains, recessive mutations in flk resulted in a reduction in intracellular FlgM levels to those seen in wild-type (Fla+) strains. The reduction in intracellular FlgM levels by mutations in the flk gene was concomitant with a 10-fold increase in transcription of the flgMN operon compared to that of the isogenic flk+ strain, while transcription of the flgAMN operon was unaffected. This was true for both direct measurement of the flgAMN and flgMN mRNA transcripts by RNase T2 protection assays and for lac operon fusions to either the flgAMN or flgMN promoter. Loss of Flk did not allow secretion of FlgM through basal-body structures lacking the P- and L-rings. Intracellular FlgM was stable to proteolysis, and turnover occurred primarily after export out of the cell. Loss of Flk did not result in increased FlgM turnover in either P- or L-ring mutant strains. With lacZ translational fusions to flgM, a null mutation in flk resulted in a significant reduction of flgM-lacZ mRNA translation, expressed from the class 3 flgMN promoter, in P- and L-ring mutant strains. No reduction in either flgAMN or flgMN mRNA stability was measured in the absence of Flk in Fla+, ring mutant, or HBB deletion strains. We conclude that the reduction in the intracellular FlgM levels by mutation in the flk gene is only at the level of flgM mRNA translation.

Authors+Show Affiliations

Department of Microbiology, University of Washington, Seattle, Washington 98195, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

9765570

Citation

Karlinsey, J E., et al. "Flk Couples flgM Translation to Flagellar Ring Assembly in Salmonella Typhimurium." Journal of Bacteriology, vol. 180, no. 20, 1998, pp. 5384-97.
Karlinsey JE, Tsui HC, Winkler ME, et al. Flk couples flgM translation to flagellar ring assembly in Salmonella typhimurium. J Bacteriol. 1998;180(20):5384-97.
Karlinsey, J. E., Tsui, H. C., Winkler, M. E., & Hughes, K. T. (1998). Flk couples flgM translation to flagellar ring assembly in Salmonella typhimurium. Journal of Bacteriology, 180(20), 5384-97.
Karlinsey JE, et al. Flk Couples flgM Translation to Flagellar Ring Assembly in Salmonella Typhimurium. J Bacteriol. 1998;180(20):5384-97. PubMed PMID: 9765570.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Flk couples flgM translation to flagellar ring assembly in Salmonella typhimurium. AU - Karlinsey,J E, AU - Tsui,H C, AU - Winkler,M E, AU - Hughes,K T, PY - 1998/10/10/pubmed PY - 1998/10/10/medline PY - 1998/10/10/entrez SP - 5384 EP - 97 JF - Journal of bacteriology JO - J Bacteriol VL - 180 IS - 20 N2 - The hook-basal body (HBB) is a key intermediate structure in the flagellar assembly pathway in Salmonella typhimurium. The FlgM protein inhibits the flagellum-specific transcription factor sigma28 in the absence of the intact HBB structure and is secreted out of the cell following HBB completion. The flk gene encodes a positive regulator of the activity of FlgM at an assembly step just prior to HBB completion: at the point of assembly of the P- and L-rings. FlgM inhibition of sigma28-dependent class 3 flagellar gene transcription was relieved in P- and L-ring assembly mutants (flgA, flgH, and flgI) by introduction of a null mutation in the flk gene (J. E. Karlinsey et al., J. Bacteriol. 179:2389-2400, 1997). In P- and L-ring mutant strains, recessive mutations in flk resulted in a reduction in intracellular FlgM levels to those seen in wild-type (Fla+) strains. The reduction in intracellular FlgM levels by mutations in the flk gene was concomitant with a 10-fold increase in transcription of the flgMN operon compared to that of the isogenic flk+ strain, while transcription of the flgAMN operon was unaffected. This was true for both direct measurement of the flgAMN and flgMN mRNA transcripts by RNase T2 protection assays and for lac operon fusions to either the flgAMN or flgMN promoter. Loss of Flk did not allow secretion of FlgM through basal-body structures lacking the P- and L-rings. Intracellular FlgM was stable to proteolysis, and turnover occurred primarily after export out of the cell. Loss of Flk did not result in increased FlgM turnover in either P- or L-ring mutant strains. With lacZ translational fusions to flgM, a null mutation in flk resulted in a significant reduction of flgM-lacZ mRNA translation, expressed from the class 3 flgMN promoter, in P- and L-ring mutant strains. No reduction in either flgAMN or flgMN mRNA stability was measured in the absence of Flk in Fla+, ring mutant, or HBB deletion strains. We conclude that the reduction in the intracellular FlgM levels by mutation in the flk gene is only at the level of flgM mRNA translation. SN - 0021-9193 UR - https://www.unboundmedicine.com/medline/citation/9765570/Flk_couples_flgM_translation_to_flagellar_ring_assembly_in_Salmonella_typhimurium_ L2 - http://jb.asm.org/cgi/pmidlookup?view=long&pmid=9765570 DB - PRIME DP - Unbound Medicine ER -