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Doctoral Thesis
DOI
10.11606/T.42.2007.tde-30012008-094907
Document
Author
Full name
Meire Aguena
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2007
Supervisor
Committee
Spira, Beny (President)
Ferreira, Rita de Cassia Cafe
Gomes, Suely Lopes
Gomez, José Gregorio Cabrera
Silva, Aline Maria da
Title in Portuguese
Análise transcricional do operon pst de Escherichia coli.
Keywords in Portuguese
Escherichia coli
Biologia Molecular
Operon pst
RNA mensageiro
RNase E
Sequências REP
Abstract in Portuguese
O operon pst de Escherichia coli é formado pelos genes pstS, pstC, pstA, pstB e phoU. Os quatro primeiros genes codificam proteínas que compõem um sistema de transporte do tipo ABC denominado Pst. O sistema Pst, junto com a proteína PhoU participa da repressão dos genes do regulon PHO. A transcrição dos genes do operon pst é induzida pela carência de fosfato inorgânico (Pi). Neste trabalho, o padrão de transcrição do operon pst foi analisado. A existência de um transcrito primário instável foi comprovada através de uma nova técnica de RT-PCR. O papel da RNase E na degradação do mRNA de pst foi demonstrado. A análise das seqüências intergênicas do operon revelou a importância da seqüência REP (Repetitive Extragenic Palindrome) localizada na região intergênica entre pstS e pstC na estabilização da mensagem de pstS. As seqüências localizadas a 5' dos genes pstC, pstB e phoU também foram analisadas e demonstraram uma atividade promotora fraca, que resulta na síntese de transcritos dos genes distais de pst.
Title in English
Transcriptional analisys of pst operon Escherichia coli.
Keywords in English
Escherichia coli
Molecular biology
mRNA
pst operon
REP sequences
RNase E.
Abstract in English
The pst operon of Escherichia coli consists of the genes pstS, pstC, pstA, pstB and phoU. The four proximal genes of the operon encode the proteins of the ABC-type Pi phosphate (Pi) transporter Pst.The Pst system, together with the PhoU protein, also acts as a negative regulator of the PHO regulon. Transcription of the pst genes is induced by Pi starvation. The present study describes the transcription pattern of the pst operon. The existence of an unstable primary transcript was confirmed by using an improved RT-PCR protocol. The role of RNase E in pst transcript decay was demonstrated.Analysis of the operon intergenic regions revealed the role of a REP sequence (Repetitive Extragenic Palindrome) located between pstS and pstC in pst mRNA stability. The regions upstream of pstC, pstB and phoU displayed promoter activity. Transcription from these internal promoters resulted in a small amount of mRNAs corresponding to the pst distal genes.
 
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Publishing Date
2008-02-07
 
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