Regulation of Erwinia carotovora hrpL(Ecc) (sigma-L(Ecc)), which encodes an extracytoplasmic function subfamily of sigma factor required for expression of the HRP regulon.
In Erwinia carotovora subsp. carotovora (Ecc) strain 71 (Ecc71), HrpL(Ecc), an alternate sigma factor of the extracytoplasmic function subfamily, plays a central role in the expression of the hrp (hypersensitive reaction and pathogenicity) regulon. We document here that sigma-54 (RpoN) is required for full expression of hrpL(Ecc) and that HrpS, in conjunction with sigma-54, activates hrpL(Ecc) transcription. We also made the novel observation that integration host factor is required for the activation of the hrpL(Ecc) promoter. Our findings reveal that the RsmA/rsmB RNA-mediated post-transcriptional system, known to control extracellular enzyme and harpin production, affects hrpL(Ecc) expression as well. For example, hrpL(Ecc) RNA levels are barely detected in an RsmB- strain. Conversely, hrpL(Ecc) mRNA levels are much higher in RsmA- bacteria than in the RsmA+ parent. This effect is due to RsmA-promoted decay of hrpL(Ecc) RNA. Moreover, the following regulators known to control the production of either RsmA, rsmB RNA, or both also affect hrpL(Ecc) expression: GacA (response regulator of a two-component system), KdgR (an IcII type repressor), HexA (a LysR type repressor), RsmC (a putative transcriptional adapter). Based upon the data now available for Ecc and extrapolating from the evidence in other systems, we propose a tentative model that depicts the Hrp regulatory system of Ecc and explains the basis for coregulation of extracellular enzyme production and expression of the Hrp regulon.
Chatterjee
Asita
A
Department of Plant Microbiology and Pathology, University of Missouri at Columbia, 65211, USA. chatterjeeas@missouri.edu
Cui
Yaya
Y
Chatterjee
Arun K
AK
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D016973:Pectobacterium carotovorum / Q000235:genetics* / Q000378:metabolism; D051877:RNA Polymerase Sigma 54; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins; D018085:Regulon / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012808:Sigma Factor / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C085855:HrpL protein, Pseudomonas syringae; D012329:RNA, Bacterial; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; C095468:RsmA protein, Erwinia carotovora; D012808:Sigma Factor; D014157:Transcription Factors; C115187:rsmb protein, Erwinia carotovora; C060789:hrpS protein, Pseudomonas syringae; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54